Swellable composite, precursor composition, and uses of same

Abstract

Described herein is a swellable composite for enhancing seed germination, comprising cellulose nanofibres (CNFs) and / or cellulose microfibres (CMFs), a water soluble polysaccharide, and optionally an active agent, as well as a precursor composition for same further comprising water, a method for making same, and a method of enhancing seed viability, seed germination, root development and / or plant growth using same.

Description

[0001] SWELLABLE COMPOSITE, PRECURSOR COMPOSITION, AND USES OF SAME Priority Cross-Reference

[0002]

[0001] The present application claims priority from Australian provisional patent application No.

[0003] 2025900181 filed on 23 January 2025, the contents of which are incorporated herein in their entirety by cross-reference.

[0004] Technical Field

[0005]

[0002] The disclosure herein relates to a swellable composite seed enhancement technology. More particularly, the disclosure herein relates to a swellable composite capable of hydrating and / or releasing one or more active agents to a seed, for example, to enhance seed germination.

[0006] Background

[0007]

[0003] Seed enhancement technologies are widely used in the agricultural seed industry for crops and horticultural seeds. They have been used to date to enhance flowability and plantability of crop seeds, as well as to provide plant growth substances to improve seed and germination quality. Some of these widely used technologies include seed film coating, encrusting and pelleting, which enhance the flowability and uniformity of seeds. However, some of the limitations associated with currently available seed coating technologies include prolonged soaking and subsequent drying, which reduces the seed viability and accelerates fungal infections, thick coatings such as encrusting and pelleting, which cuts oxygen supply to the seeds, causing germination or seedling emergence delay, and the adverse impact of specific substances and microplastics in coating components, which contribute to environmental pollution. To date, there has also been limited exploration of seed coatings for native Australian plant seeds in particular, which are expensive to harvest and have a low germination efficiency, especially in arid lands where they may be required to support ecological restoration projects such as mine rehabilitation, for example.

[0008]

[0004] Improved seed enhancement technologies that address one or more of the above problems, or at least provide a useful alternative, are therefore desirable.

[0009]

[0005] One plant family of particular interest for seed enhancement is legumes. Symbiotic nitrogen fixation is the greatest natural contributor to the global nitrogen (N) cycle and occurs when a microorganism (such as a Rhizobium spp.) and host (such as a legume) convert atmospheric nitrogen (N2) into ammonium (NH4+). Humans have known since the Ancient Greek period that legumes “manure” a crop and first observed the symbiotic relationship between legumes and plant growth promoting rhizobacteria (PGPR) within root nodules in the 1700s. Today, symbioses in agroecosystems are estimated to fix 50-80 Tg N annually, almost equivalent to the 88 Tg N industrially fixed into fertilisers.

[0010]

[0006] By 2050, the global population is projected to reach 9.7 billion and the majority of this growth is expected in less developed countries. Yet resources, including synthetic N, are limited in poorer regions. Accordingly, innovation that enhances N2 fixation will improve global food security. As the world’s top producers of the most important legume crop, soybean, South American growers rely on symbiotic N2 fixation to ensure high soybean yields without the need for synthetic N. In Brazil alone, in 2019-20, it is estimated that 15.2 billion USD worth of synthetic N was replaced by N2 fixation, accounting for 183 million Mg CO2-e mitigated (equivalent to €5 billion in carbon credits). Annualreinoculation is crucial to this success, increasing yield by 8% even in rhizobia abundant soils. In parallel, an oversupply of synthetic N in industrialised agriculture is one of humanity’s greatest polluters, resulting in eutrophication, air pollution, biodiversity loss, climate change and ozone depletion. Thus, greater N2 fixation promotes sustainability and environmental stewardship by improving soil quality and reducing N losses through denitrification, volatilisation and leaching.

[0011]

[0007] Breakthroughs in strain identification and increasingly sophisticated inoculation techniques were explored in the 20thcentury, but poor PGPR survival in storage and soil, contamination by undesirable microbes, high production costs and inconvenient handling and transportation continue to plague inoculants, while delivery of rhizobia to seed via priming (biopriming) and seed coating can severely compromise seed and / or microbe quality.

[0012]

[0008] Improved methods of enhancing the growth of seeds and plants, such as legumes, that address one or more of the above problems or at least provide a useful alternative, are therefore desirable.

[0013]

[0009] In one aspect, the invention described herein provides a seed enhancement technology platform that utilises a swellable composite comprising cellulose nanofibres or ‘nanofibrils’ (CNFs) and / or cellulose microfibres (CMFs) and a water soluble polysaccharide. The swellable composite is capable of encapsulating one or more active agents, such as plant growth regulators, peptides, microbes, and / or pesticides, and when swelled at or around a seed, absorbs water to provide hydration and / or controlled release of the active agent to aid germination and growth. The seed enhancement technology platform described herein offers one or more advantages over currently available seed coating technologies, particularly in arid environments.

[0014]

[0010] A reference herein to a patent document or other matter which is given as prior art is not to be taken as an admission that the document or matter was known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims.

[0015] Summary of the Invention

[0016]

[0011] Unless the context indicates otherwise, where the terms “comprise”, “comprises” and “comprising” are used in the specification (including the claims) they are to be interpreted as specifying the stated features, integers, steps or components, but not precluding the presence of one or more other features, integers, steps or components, or group thereof.

[0017]

[0012] According to a first aspect of the present invention, there is provided a precursor composition, comprising: cellulose nanofibres (CNFs) and / or cellulose microfibres (CMFs); a water soluble polysaccharide; and water. In one embodiment, the precursor composition comprises cellulose nanofibres (CNFs) and / or cellulose microfibres (CMFs); a water soluble polysaccharide; an active agent; and water.

[0018]

[0013] The CNFs and CMFs collectively, or the CNFs, or the CMFs, may be present at a concentration of less than 1 wt%. The CNFs and CMFs collectively, or the CNFs, or the CMFs, may be present at a concentration of from 0.1 wt% to 0.6 wt%. The CNFs and CMFs collectively, or the CNFs, or the CMFs, may be present at a concentration of from 0.2 wt% to 0.4 wt%. The CNFs and CMFs collectively, or the CNFs, or the CMFs, may be dispersed in the precursor composition. The water soluble polysaccharide may be present at a concentration of less than 5 wt%, or of from 0.01wt% to 5 wt%, or of from 0.5 wt% to 1.5 wt%. The water may be present in an amount of at least 95 wt%, or of at least 98 wt%.

[0019]

[0014] According to a second aspect of the present invention, there is provided a swellable composite for enhancing seed viability, seed germination, root development and / or plant growth, comprising: cellulose nanofibres (CNFs) and / or cellulose microfibres (CMFs); and a water soluble polysaccharide. In one embodiment, the swellable composite comprises cellulose nanofibres (CNFs) and / or cellulose microfibres (CMFs); a water soluble polysaccharide; and an active agent. In one embodiment, release of the active agent from the controlled release swellable composite is hydration-activated. In one embodiment, the active agent is for controlled release on swelling of the swellable composite in water, optionally wherein the swellable composite has a swellability of at least 10,000% after a period of 30 min immersion in water at 25°C.

[0020]

[0015] The swellable composite may be in the form of a film, a prill, ora capsule. In one embodiment, the swellable composite is dry, in one embodiment comprising <1 wt% water. Accordingly, in one embodiment, there is provided a swellable composite for enhancing seed germination, comprising: CNFs; and a water soluble polysaccharide, wherein the swellable composite comprises less than 5 wt%, less than 4 wt%, less than 3 wt%, less than 2 wt%, or less than 1 wt% water. In one embodiment, there is provided a swellable composite for enhancing seed germination, comprising: CNFs and / or CMFs; and a water soluble polysaccharide, wherein the swellable composite is dry, such as dry to touch. The swellable composite may comprise less than 60 wt% of CNFs and CMFs collectively, CNFs, or CMFs. It may comprise from 10 wt% to 60 wt% of CNFs and CMFs collectively, CNFs, or CMFs, or of from 20 wt% to 45 wt% of CNFs and CMFs collectively, CNFs, or CMFs.

[0021]

[0016] The swellable composite may comprise at least 40 wt%, or of from 40 wt% to 90 wt% water soluble polysaccharide. In one embodiment, it comprises from 55 wt% to 80 wt% water soluble polysaccharide. The swellable composite may be a film-forming swellable composite.

[0022]

[0017] The dispersed CNFs in the precursor composition and / or swellable composite may have diameters of from 1 to 20 nm, a length of from 500 to 2,500 nm, and an aspect ratio of from 200 to 1,000. The CNFs may be obtained from a spinifex grass within the genera Triodia, Monodia, or Symplectrodia. The CNFs may be sourced from T. pungens, T. shinzii, T. basedowii or T. longiceps. The CNFs may be obtained in a process comprising deep eutectic solvent treatment and high pressure homogenisation.

[0023]

[0018] The water soluble polysaccharide may have a solubility in water of at least than 33 mg / L at a temperature of 25 °C. It may have a solubility in water of more than 100 mg / L at a temperature of 25 °C. The water soluble polysaccharide may be selected from a mannan, a galactomannan, a xylan, a pectin, a dextran, an arabinogalactan, a xanthan, a pullulan, an agar, an alginate, a carboxymethylcellulose (CMC), an agarose, and a hyaluronic acid, or a combination thereof. The water soluble polysaccharide may be a non-ionic polysaccharide. In one embodiment, the non-ionic polysaccharide is selected from a dextran, a pullulan, an agar, and a guar gum, or a combination thereof. In one embodiment, the water soluble polysaccharide is a glucan. The glucan may be a dextran or a pullulan.

[0019] The dispersed CNFs and / or CMFs and water soluble polysaccharide may be present in a mass ratio of CNFs and / or CMFs:polysaccharide of from 1:1 to 1:5, or of from 1:2 to 1:4, or of from 1:2.5 to 1:3.5.

[0024]

[0020] The active agent may be selected from one or more of: a plant growth regulator, a peptide, a microbe, a fungicide, and a pesticide. The active agent may comprise a plant growth regulator and / or a microbe and / or a fungicide, that is, may comprise a PGR and a microbe, or a PGR and a fungicide, or a microbe and a fungicide, or any one of these individually.

[0025]

[0021] The active agent may be a plant growth regulator. In one embodiment, the plant growth regulator is selected from a karrikin and a plant growth promoter such as an auxin, a gibberellin, a cytokinin, a brassinosteroid, or zeatin. The active agent may a plant growth regulator and present in the precursor composition in a concentration sufficient to provide from 0.1 ng to 5000 ng of the active agent per seed, or in another embodiment of from 0.1 ng to 2000 ng of the active agent per seed.

[0026]

[0022] The active agent may be a peptide. In one embodiment, the peptide is selected from a linear peptide or a cyclotide. The linear peptide may be a CLE peptide, a systemin, or a root hair promoting peptide (RHPP). The cyclotide may be kalata B1. The active agent may be a peptide and present in the precursor composition in a concentration sufficient to provide from 2 g to 5 pg peptide per seed.

[0027]

[0023] The active agent may be a fungicide. In one embodiment, the fungicide may be formulated for application to seeds and / or targets one or more soil-borne and / or seed-borne fungi. The fungicide may be selected from one or more of: thiram, captan, carboxin, metalaxyl, fludioxonil, difenoconazole, tebuconazole, azoxystrobin, thiamethoxam, triadimenol, mancozeb, pyraclostrobin, sedaxane, and penflufen. The active agent may be a fungicide and present in the precursor composition in a concentration sufficient to provide from 0.2 ng to 20 pg fungicide per seed.

[0028]

[0024] The active agent may be a microbe or plant growth promoting microorganism (PGPM). The PGPM may be a plant growth promoting rhizobacteria (PGPR) or a beneficial fungus. The active agent may be a plant growth promoting rhizobacteria (PGPR) selected from a nitrogen fixing PGPR selected from one or more of the genera Rhizobium, Sinorhizobium, Azorhizobium, Allorhizobium, Mesorhizobium, Bradyrhizobium, Burkholderia, and Herbaspirillum spp., preferably from the genera Rhizobiunr, and a non-nitrogen fixing PGPR selected from the genera Bacillus spp. and / or Pseudomonas spp. The active agent may be a beneficial fungus selected from a mycorrhizal fungus from the phyla Glomeromycota, Ascomycota or Basidiomycota, a Trichoderma spp., or Penicillium bilaiae. The active agent may be a microbe and present in the precursor composition in a concentration sufficient to provide from 1 x 106to1 x 109Y CFU microbes per seed.

[0029]

[0025] According to a third aspect of the present invention, there is provided a swellable composite according to the second aspect above when made from a precursor composition according to the first aspect above.

[0030]

[0026] According to a fourth aspect of the present invention, there is provided a method of enhancing seed viability, seed germination, root development and / or plant growth, comprising: priming a seed with a precursor composition according to the first aspect above.

[0031]

[0027] The method may comprise wet priming the seed and sowing the seed while the precursor composition is still wet, or may comprise injecting the precursor composition onto the seed. Themethod may comprise wet / dry priming, that is, priming the seed with precursor composition, allowing the seed with the precursor composition coating to dry to form a dried layer of swellable composite around the seed, and subsequently planting the dried seed with swellable composite coating.

[0032]

[0028] According to a fifth aspect of the present invention, there is provided a method of enhancing seed viability, seed germination, root development and / or plant growth, comprising: co-planting a seed with or within a swellable composite according to the second aspect above. In one embodiment, the method further comprises applying water to the swellable composition to cause it to swell.

[0033]

[0029] Co-planting may comprise wrapping, packaging, or encapsulating the seed within a swellable composite film or cellophane wrap, package or capsule, or may comprise planting the seed adjacent to a prill of film or cellophane dot or sheet of the swellable composite.

[0034]

[0030] The seed may be a commercially significant plant seed. In one embodiment, the seed is selected from soybean, wheat, cotton, rice, barley, oats, sorghum, canola (rapeseed), sunflower, sugarcane, oil palm, and cassava. The seed may be a leguminous plant, in one embodiment selected from soybean, peanut, bean, chickpea, and lentil. The seed may be an Australian native plant seed, in one embodiment selected from the Myrtaceae, Proteaceae, Fabaceae, Haemodoraceae, Rutaceae, Ericaceae, Goodeniaceae, Asteraceae, Casuarinaceae, Asparagaceae, Poaceae, Apocynaceae, Solanaceae, Santalaceae, and Cunoniaceae families.

[0035]

[0031] In the method, the swellable composite may comprise an active agent, wherein the active agent is a plant growth regulator and is present in the swellable composite at a concentration of from 0.1 ng to 5000 ng of the active agent per seed, or the active agent is a peptide and is present in the swellable composite at a concentration of from 2 g to 5 pg stable peptide per seed, or wherein the active agent is a fungicide and is present in the swellable composite at a concentration of from 0.2 ng to 18 ng fungicide per seed, or wherein the active agent is a microbe and is present in the swellable composite at a concentration of from 1 x 106to 1 x 109CFU microbes per seed.

[0036]

[0032] According to a sixth aspect of the present invention, there is provided use of a swellable composite according to the second aspect above as a plant tissue culture medium. In one embodiment, the swellable composite is swelled or hydrated in use.

[0037]

[0033] According to a seventh aspect of the present invention, there is provided a method of producing a precursor composition, comprising: mixing a water soluble polysaccharide, cellulose nanofibres (CNFs) and / or cellulose microfibres (CMFs), and optionally an active agent, in water.

[0038]

[0034] According to an eighth aspect of the present invention, there is provided a method of producing a swellable composite for enhancing seed germination, comprising: providing a precursor composition comprising a water soluble polysaccharide, cellulose nanofibres (CNFs) and / or cellulose microfibres (CMFs), and optionally an active agent, in water; applying a quantity of the precursor composition to a surface; and allowing the precursor composition to dry on the surface, thereby forming the swellable composite.

[0039] Brief Description of Drawings

[0040]

[0035] Embodiments of the invention will herein be illustrated by way of example only with reference to the accompanying drawings in which:

[0036] Figure 1 illustrates the source and structure of cellulose nanofibres used in the swellable composite according to an embodiment of the invention as described herein: (a) ‘cellulose nanofibrils’ or CNF extracted from spinifex grass fibres; (b) Transmission electron micrograph images (TEM) of CNFs from spinifex showing their web-like structures; (c) High-resolution TEM images showing the thin diameter and abundant length of spinifex CNFs that conveys their very high aspect ratio; (d) Cellulose nanocrystals or ‘CNCs’ make up cellulose of most species and form short ‘rod-like’ or elongated ‘rice-like’ structures with low aspect ratios;

[0041]

[0037] Figure 2 shows a cotton or native seed inside (a,b) a capsule; (c) a heat sealed cellophane pocket; (d) a water sealed cellophane pocket; comprised of a swellable composite according to an embodiment of the invention as described herein;

[0042]

[0038] Figure 3 shows the synthesis and film properties of a swellable composite according to an embodiment of the invention as described herein: (a) pullulan, CNFs and PGPR are combined to form a precursor solution before being formed into ‘dots’ containing PGPR that are allowed to dry to form the swellable composite and applied around a seed; (b) the upper surface and (c) cross-section of the dry swellable composite ‘dot’ as observed by scanning electron microscopy;

[0043]

[0039] Figure 4 shows successful PGPR encapsulation, delivery and nodulation: stereo microscopy of swellable composite dots according to an embodiment of the invention as described herein: (a) control empty swellable composite without PGPR; (b) swellable composite dot with Ds-Red PGPR under a brightfield filter; (c) fluorescence observed from Ds-Red PGPR under Ds-Red filter, magnification = 0.75x (scale bars = 5000 pm); widefield microscopy of DS-Red PGPR within the wetted swellable composite: (d) emitting bright red fluorescence from wet bacterial film, magnification = 200x (scale bar= 100 pm); (e) emitting fluorescence from single bacilli under 600x magnification in the swellable composite (scale bar = 50 pm); across two separate experiments (time 1 and 2) nodulation was quantified for 4-week-old soybean plants grown in vermiculite; root nodules were quantified for untreated plants (Un, sown as bare seed, absolute control), plants with seeds wrapped by an empty swellable composite (EN, control without PGPR) or plants with seeds wrapped with a swellable composite containing Ds-Red PGPR (DsRN): (f) average number of root nodules per plant;

[0044] (g) abundant nodules form on plants treated with Ds-Red PGPR (DsRN) while no nodules form on untreated (Un, absolute control) or empty swellable composite-treated (EN, control without PGPR) plants; (h) fluorescence electron microscopy shows a nodule glowing red on a DsRed PGPR-treated plant; (i) confocal microscopy highlights the internal part of the nodule glowing red for plants treated with the swellable composite containing DsRed PGPR;

[0045]

[0040] Figure 5 shows successful nitrogen fixation from swellable composite-delivered PGPR according to an embodiment of the invention as described herein: across two separate experiments (time 1 and 2) plant nitrogen fixation, as determined by chlorophyll content and plant size, and root architecture were quantified for 4-week-old soybean plants grown in vermiculite. Parameters were quantified for untreated plants (Un, sown as bare seed, absolute control), plants with seeds wrapped by an empty swellable composite (EN, control without PGPR) or plants with seeds wrapped with a swellable composite containing Ds-Red PGPR (DsRN); (a) chlorophyll a and b concentration per fresh weight of leaf; (b) SPAD value, indicating chlorophyll content; (c)-(e) plant height and colour; (f)-(h)root proliferation, as quantified by root surface area, volume and number of root tips. In (a)-(c) and (g) box plots, 25th-75thpercentile; centre line, median; numbers below plot, mean; whiskers, full data range. The numbers represent P values (T ukey test, a = 0.05) after a GLM ANOVA test, with block as a random factor (GraphPad Prism v 10.1.2). The exact sample sizes for each block (n, true biological replication) are given as discrete numbers in each panel;

[0046]

[0041] Figure 6 shows KARi resulted in root proliferation in wheat when treated with a swellable composite according to an embodiment of the invention as described herein comprising 25.4 wt% CNF cellophane, and 40.5 wt% CNF cellophane, containing varying concentrations of KARi per seed (horizonal axis) at 1 week post sowing;

[0047]

[0042] Figure 7 shows KARi delivery to native Solanum orbiculatum seeds in either a swellable composite according to an embodiment of the invention described herein (“Cellophane”; 0.5 mL dried dot) or current “best” priming technology, seeds imbibed on agar gel containing KARi for 48 h prior to planting (“Petri dish”, see Kochanek et al 2011; Berto et al 2021), whereby (a) 65% of seedlings emerged and survived when 200 ng KARi was delivered to each seed in Cellophane, versus <5% for the untreated absolute control and Cellophane without KARi (NB: 200 ng KARi per seed in Cellophane equivalent dose in agar Petri dish); and (b) cellophane increased root growth relative to the untreated absolute control, showing soil delivered KARi as effectively as agar in a Petri dish in a laboratory;

[0048]

[0043] Figure 8 shows aging and fungally contaminated Solanum orbiculatum seeds treated with (a) a fungal suppressant (Evergol Energy®, “Evergol”. Bayer) in a swellable composite according to an embodiment of the invention in cellophane form (“B-Tech”; 0.5 mL dried dot) with and without 200 ng KARi seed-1, where seeds treated with KARi significantly improved emergence, with and without the fungicide (30% of the industry recommended Evergol Energy® dose for cotton to suppress cotton fungus, Fusarium oxysporum, was used due to the seed being 30% of the size of the cotton seed); (b) a fungal suppressant (Evergol Energy®, “E”, Bayer) at either 25%, 50%, 75% or 100% of the cotton seed dose in a swellable composite according to an embodiment of the invention in the form of cellophane (“B-Tech”, 0.5 mL dried dot) with 200 ng KARi seed'1; (c) a fungal suppressant (Vibrance® CST, “V”, Syngenta) in swellable composite according to an embodiment of the invention in the form of a cellophane (“BTech”; 0.5 mL dried dot) with and without 200 ng KARi seed'1(“K”), 150% of the cotton dose of Vibrance® CST was used per seed;

[0049]

[0044] Figure 9 shows aging and fungally contaminated Solanum orbiculatum seeds treated with a fungal suppressant (Evergol Energy®, “E”, Bayer) at either 25%, 50%, 75% or 100% the cotton seed dose in a swellable composite according to an embodiment of the invention in the form of cellophane (“B-Tech”; 0.5 mL dried dot) with 200 ng KARi seed'1, where root size was better for Evergol 50% + KARi than for 100% Evergol + KARi, indicative that Evergol at 75 or 100% was an overdose because root size was compromised by these doses, while Evergol at 25-50% was optimal;

[0050]

[0045] Figure 10 shows a swellable composite according to an embodiment of the invention in the form of cellophane (0.5 mL dried dot) versus untreated seeds orwet / dry primed seeds using precursor composition according to an embodiment of the invention with varying KARi dosages with fresh seeds of the native species S. orbiculatum. Fresh seeds may be wet primed if they are at low risk of fungal contamination;

[0046] Figure 11 shows survival rate for Scaevola albida seeds treated with fungal suppressant (Evergol Energy®, “Evergol”, Bayer; 30% of cotton dose) in a swellable composite according to an embodiment of the invention in the form of cellophane (“B-Tech”; 0.5 mL dried dot) without KARi or with 20 ng or 200 ng KARi seed'1in a field trial (sown outdoors into soil). The combination of 20 or 200 ng KARi with 30% Evergol Bayer fungicide yielded the best results (40-44% seedling survival) versus the B-Tech without KARi (24%) and the untreated control (8%, P <0.0001) in pot trial (data not shown), and in field trials as shown the combination of 200 ng KARi with 30% Evergol Bayer fungicide yielded the best results, with 58-67% of plants emerging relative to the B-Tech without KARi (8% emergence) and the untreated seed (absolute control, 13% emergence, P<0.0001);

[0051]

[0047] Figure 12 shows survival rate for Hibbertia diffusa seeds treated with fungal suppressant (Evergol Energy®, “Evergol”, Bayer; 30% of cotton dose) in a swellable composite according to an embodiment of the invention in the form of cellophane (“B-Tech”; 0.5 mL dried dot) without KARi or with 20 ng or 200 ng KARi seed'1in a field trial (sown outdoors into soil). At 48% survival in pots and 58% survival in field trials, swellable composite treated seeds outperformed the survival of seeds primed in agar with KARi equivalent to 200 ng, which had only 33% survival (data not shown), and is therefore superior to agar priming. Additionally, as Hibbertia diffusa has a hard seed coat, the swellable composite may soften the coat to allow easier seedling emergence;

[0052]

[0048] Figure 13 shows that when Leptospermum erubescens seeds were (a) primed on agar with KARi equivalent to 200 ng, 61% of seeds germinated, which was slightly more than the untreated control (51%) and significantly more than with GA3 (30%); (b) transferring these seedlings to soil resulted in only 32% survival for 200 ng equivalent KARi treated plants (and 24% for untreated and 4% for G A3 treated plants). Hence, KARi (and not GA3) was incorporated into the swellable composite for pot and field validation studies; (c) pot trials in a temperature-controlled growth cabinet tested a 20 or 200 ng KARi swellable composite according to an embodiment of the invention in the form of cellophane compared to untreated seed (absolute control) and swellable composite without actives (B-Tech control). Two swellable composite sizes were compared, made with (c) 0.25 mL or(d) 0.5 mL precursor composition, and the dry swellable composite was applied as a prill below the seed (triangle symbol) or wrapped around the seed (square symbol). The 0.25 mL prill containing 20 ng KARi and the 0.5 mL prill containing 200 ng KARi yielded the best results, both being better than the untreated control (P<0.0001);

[0053]

[0049] Figure 14 shows (a) top, dry swellable composite according to an embodiment of the invention and bottom, swollen / rehydrated swellable composite; and (b) swelling ratio data of the swellable composite in water compared to a comparative literature seed coating technology in saline, possibly due to comparative technology disintegrating in water;

[0054]

[0050] Figure 15 shows PGR release into free water from a swellable composite according to an embodiment of the invention;

[0055]

[0051] Figure 16 shows MALDI-TOF analysis of purified cyclotides encapsulated in a swellable composite according to an embodiment of the invention: (a) Empty swellable composite with no cyclotide; (b) swellable composite with cyclotide kalata B1 (kB1), cyclotide structure included (PDB ID - 1NB1); (c) swellable composite with cyclotide Cycloviolacin 02 (CyO2), cyclotide structure included(PDB ID - 2KNM); and (d) swellable composite with cyclotide hyen D, cyclotide structure included (PDB ID - 7RN3). The swellable composites maintained the same spectrum when tested again after 6 months of shelf-life storage in moisture-free dark conditions at room temperature;

[0056]

[0052] Figure 17 shows quantification of a cyclic and a linear peptide contained within a swellable composite according to an embodiment of the invention: MALDI-TOF of a prototype containing (a) cyclic peptide kB1 (total quantification using QTRAP 6500+ LC-MS / MS revealed that swellable composite retained 63.3% of cyclotide kB1 (n=10)); (b) linear peptide, hairy root promoting peptide (RHPP) (total quantification using LC-MS revealed that swellable composites retained 52% of linear peptide RHPP (n=3));

[0057]

[0053] Figure 18 shows that swellable composites according to certain embodiments described herein (0, 2, 20, 200 ng KARi) show an increased rate of seedling emergence for Sicot 620 V2 cotton seeds (non-transgenic), whereby 40% of BT treated seeds had emerged at 21 d after sowing even at very low temperatures of 14 °C, while 0% of CSD (seeds coated with Vibrance CST, Bion and Cruiser fungicides) seedlings had emerged at this time. The final emergence of seeds wrapped with KARi containing swellable composites was 90%, but only 80% for CSD coated seeds;

[0058]

[0054] Figure 19 shows that when fungicide actives and KARi were incorporated into a prill of a swellable composite as described herein and co-planted with cotton seeds, even when the fungicide active concentration of Vibrance CST was halved relative to a standard coating dose and used with 20 ng KARi (50VBC+K_P), (a) emergence of transgenic Sicot 761B3XF V2C cotton seedlings was significantly accelerated in composite prill-co-planted seeds relative to CSD seeds (b) at day 4, and that (c) roots proliferated at 7 days after sowing. The same trend was observed for root tip number, root length and root surface area. (Untreated = bare seed, CSD = seeds coated with V, B and C; V = Vibrance CST, B = Bion, C = Cruiser, K = 20 ng KARi per seed, 100 = 100% cotton dose, 50 = 50% cotton dose; and

[0059]

[0055] Figure 20 shows data for (a) agar priming and (b) swellable composite priming of Eucalyptus melliodora seeds with 200 ng KARi or equivalent dose. Agar priming had a 70% seed germination rate, whereas the swellable composite had an 85% germination rate 8 days post-sowing.

[0060] Detailed Description

[0061]

[0056] Described herein is a swellable composite and precursor composition useful for enhancing seed germination. The swellable composite comprises cellulose nanofibres or ‘nanofibrils’ (CNFs) and / or cellulose microfibres (CMFs) and a water soluble polysaccharide, and optionally further comprises one or more active agents such as plant growth regulators, peptides, microbes, and / or pesticides, such that when the swellable composite is swelled at or around a seed, it absorbs water to provide hydration and / or controlled release of the active agent to the seed to aid germination. This technology can successfully deliver different active agents to plants, resulting in benefits including one or more of: faster seedling growth, customised plant growth, higher crop yields, and / or improved resistance to environmental stresses.

[0062]

[0057] Unlike other seed coating technologies, the swellable composite described herein in certain embodiments is able to be pre-dried and used to encapsulate, wrap or otherwise co-plant with dry seeds, which minimises the risk of fungal infection and / or water-initiated decay of the seeds. In certainembodiments herein, the swellable composite described herein is dry and used in dry form to encapsulate, wrap or otherwise co-plant with dry seeds. Other prior art solutions that rely on wet priming of seeds tend to suffer from fungal infection of the seeds after planting and hence lower plant survival rates.

[0063]

[0058] The swellable composites in certain embodiments herein are also capable of delivering very precise doses of plant actives to seeds throughout germination, which is not possible with traditional active application techniques like spraying or priming. In some cases, the delivery of the doses of actives is so targeted that the swellable composites described herein are able to outperform industrybest standard agar priming techniques. This surprising finding means that the swellable composites herein have utility in delivery of a wide range of plant growth regulators, which must often be finely tuned in concentration in order to optimally impact germination and growth. Furthermore, precise dosing in the swellable composites herein may allow for lower quantities of actives to be administered compared to contact or systemic application of the same active, where in some embodiments administered concentrations may be as low as nanograms per seed.

[0064]

[0059] The superior swellability of the swellable composites described herein in certain embodiments, many orders of magnitude higher than other seed coating technologies, and ability to adjust the cohesive strength of the composite through adjusting its composition, allows for a sustained delivery of active agents over a tuneable period of time, variable from hours to days to weeks, as the composite continues to expand and dissolve, releasing active agents into the seed microenvironment until it eventually completely biodegrades. This simple tuning of release rate, and simple synthesis method, make this technology ideal for commercial scale up. Furthermore, the versatility of the swellable composite allows for a broad range of active agents to be used, ranging in size and structure from simple, small organic molecules to much more complex, larger living microbes, and indeed combinations of different actives in different concentrations in the same swellable composite.

[0065]

[0060] Advantages of the technology platform described herein in certain embodiments include one or more of the following:

[0066] • The seeds can be kept dry and safeguarded from seed degradation, e.g., due to fungal infections;

[0067] • The seeds can be precisely dosed with active agents and avoid waste associated with sprays and the like;

[0068] • The swellable composite is completely biodegradable, and avoids release of microplastics into the environment;

[0069] • The swellable composite is solid, avoiding issues with powder-based technologies including dusting off and environmental pollution, e.g., unintentional insecticide spread to pollinators.

[0070]

[0061] As used herein, the term “precursor composition” refer to a composition comprising cellulose nanofibres (CNFs) and / or cellulose microfibres (CMFs), a water soluble polysaccharide, water, and optionally one or more active agents. The precursor composition is one which, when applied to a surface or mould, dries to form a solid, swellable composite, such as in the form of a film, cellophane, prill, capsule, coating, or the like.

[0062] As used herein, the term “swellable composite” refers to a solid, dried or dehydrated substance comprising cellulose nanofibres (CNFs) and / or cellulose microfibres (CMFs), a water soluble polysaccharide, and optionally one or more active agents. The swellable composite may comprise some residual water, but is preferably completely or substantially completely dehydrated such that it is dry to touch. The swellable composite may be a film-forming swellable composite that coalesces into a coherent, continuous film. The swellable composite is rehydratable or swellable on application of water.

[0071]

[0063] As used herein, the term “hydrated” or “swelled” and related terms in relation to the swellable composite refer to a swellable composite comprising cellulose nanofibres (CNFs) and / or cellulose microfibres (CMFs), a water soluble polysaccharide, and optionally one or more active agents that was previously dried into a film, coating, prill, capsule or cellophane and has been subsequently rewetted with water to form a swollen swellable composite, optionally, a swollen composite hydrogel.

[0072]

[0064] It should be understood that any numerical range recited herein is intended to include all subranges subsumed therein. For example, a range of "from x to y" or “between x and is intended to include all sub-ranges between x and y and also range end points x and y.

[0073]

[0065] As used herein, the singular forms “a,” “an,” and “the” may refer to plural articles unless specifically stated otherwise.

[0074]

[0066] The swellable composites herein comprise cellulose nanofibres (CNFs) and / or cellulose microfibres (CMFs). In one embodiment, the swellable composites herein comprise cellulose nanofibres (CNFs). In another embodiment, the swellable composites herein comprise cellulose microfibres (CMFs). In a further embodiment, the swellable composites herein comprise cellulose nanofibres (CNFs) and cellulose microfibres (CMFs), such as a mixture of the two.

[0075]

[0067] The term “CNF” and related terms “cellulose nanofibres”, “nanofibrillated cellulose” or “cellulose nanofibrils” are used interchangeably herein, and all refer to cellulose fibres or fibre bundles having diameters in the range of from 1 to 20 nm, lengths in the range of from 500 to 2,500 nm, and high aspect ratios (ratio of fibre length to fibre diameter) in the range of from 200 to 1,000. As shown in Figure 1 herein, individual CNFs derived from spinifex grasses have a very high aspect ratio, with lengths ranging from ~250 nm to ~1 ,000 nm (527 ± 185 nm), primarily due to very thin diameters of from 1 nm to 8 nm (average diameter 3.5 ± 0.8 nm; average length 1 ,686 ± 591 nm). CNFs herein have a highly reactive surface that is modular, with high surface area, surface energy and a high density of hydroxyl groups which increase its affinity for interaction with other compounds including water and scope for chemical modulation. The CNFs may be moderately crystalline and filament-like, and form complex, web-like structures where nanofibrils are entangled into long ropey structures that strengthen upon drying. The present inventors have found that such fibres have ideal properties, including surface area and energy, for formation of swellable composite films.

[0076]

[0068] Cellulose microfibres (CMFs), also known as microfibrillated cellulose or cellulose microfibrils, comprise CNFs are distinct from CNFs described above. CMFs / microfibrillated cellulose comprises fibres or fibre bundles with diameters in the range of from 20 nm to 100 nm and lengths in the range of from 0.5 mm to ~20 mm or more. Refinement and separation of microfibrillated cellulose is required to isolate the thinner CNFs it comprises.

[0069] For clarity, cellulose nanocrystals (CNCs) are distinct from CNFs and CMFs. CNCs are rodlike or whisker shaped particles having diameters of from 3 nm to 5 nm, lengths of from 50 to 500 nm, and therefore low aspect ratios of less than about 100 (and usually of from 5 to 70). CNCs are essentially 100% cellulose and are highly crystalline (54-88% crystalline) and are generally formed from acid hydrolysis (typically using sulfuric or hydrochloric acid) of microfibrillated or nanofibrillated cellulose. In one embodiment, CNCs may be used in the swellable composites and precursor compositions herein. In such embodiments, the CNCs may be combined with CNFs and / or CMFs in the swellable composites and precursor compositions herein. In one embodiment, the CNCs are excluded from the swellable composites and precursor compositions herein. In such embodiments, the CNFs and / or CMFs in the swellable composites and precursor compositions herein may be devoid of CNCs.

[0077]

[0070] Lignocellulosic materials such as CNFs / CMFs are derived from plant cell walls comprising strands of crystalline and amorphous cellulose phases supported by hemicellulose webs and strengthened by lignin. Accordingly, the CNFs and / or CMFs herein may comprise cellulose, hemicellulose, and lignin, and optionally additionally extractives such as resins. In some embodiments, the CNFs and / or CMFs comprise from 10 to 25 wt% lignin, from 35 to 70 wt% cellulose, from 10 to 50 wt% hemicellulose, and from 2 to 10 wt% extractives. Persons of skill in the art will be familiar with standard methods to measure lignocellulosic compositions of plants and the hemicellulose fraction present, such as TAPPI standard methods. These methods are described in more detail in WO 2019 / 237149 A1, the entire contents of which are incorporated herein by crossreference.

[0078]

[0071] In certain embodiments, the CNFs and / or CMFs herein may comprise a certain amount of hemicellulose. In one embodiment, the CNFs and / or CMFs herein may comprise any suitable percentage by weight of hemicellulose, being a percentage by weight of hemicellulose as a fraction of the total weight of the lignocellulosic components of the CNFs and / or CMFs. In one embodiment, the CNFs and / or CMFs may comprise hemicellulose in an amount of 10 wt% or more, or 15 wt% or more, or 20 wt% or more, or 25 wt% or more, or 30 wt% or more, or of from 30 to 55 wt%, or from 30 to 50 wt%, or from 36 to 48 wt%, or from 40 to 48 wt%, or from 42 to 47 wt%. In some embodiments, the hemicellulose content of the CNFs and / or CMFs is at least 30 wt% of the total lignocellulosic components of the CNFs. The hemicellulose may be distributed throughout the CNFs and / or CMFs on the surface of and / or in between fibres. These hemicellulose contents may contribute to the swellability of the final formed composites herein, as well as imparting toughness and flexibility to the films they form, and / or may assist with fibrillation into individual cellulose nanofibres due to negative charge repulsion between fibrils.

[0079]

[0072] The CNFs and / or CMFs herein may be derived from any suitable origin. In one embodiment, the CNFs and / or CMFs are of plant origin and therefore derived from a plant source. In one embodiment, the plant is one that contains more hemicellulose by weight than lignin. In one embodiment, the plant is a grass species having C4 anatomy. In one embodiment, the plant is a drought-tolerant grass species. In one embodiment, the plant is an arid grass species. In one embodiment, the plant is an Australian native arid grass known as “spinifex”. Spinifex (also known as‘porcupine’ and ‘hummock’ grass) is the long-established common name for three genera which include Triodia, Monodia, and Symplectrodia (and not to be confused with the grass genus Spinifex that is restricted to coastal dune systems in Australia). In one embodiment, the plant is of the genus Triodia. Hummock grassland communities in arid Australia are dominated by spinifex species of the genus Triodia, of which there are 69 described species. Of the 69 species, abundant species include the soft species, T. pungens and T. shinzii, and the hard species, T. basedowii and T. longiceps. T. pungens plants have a typical leaf composition of 33% cellulose, 44% hemicellulose, and 23% lignin.

[0080]

[0073] Examples of other grasses with C4 leaf anatomy that may be used to form CNFs and / or CMFs suitable for use in the present invention are described in WO 2019 / 237149 A1. These include Digitaria sanguinalis (L) Scopoli, Panicum coloratum L. var. makarikariense Goossens, Brachiaria brizantha (Hochst. Ex A. Rich) Stapf, D. violascens Link, P. dichotomiflorum Michaux, B. decumbens Stapf Echinochloa crusgalli P. Beauv., P. miliaceum L., B. humidicola (Rendle) Schweick., Paspalum distichum L., B. mutica (Forsk.) Stapf, Setaria glauca (L.) P. Beauv, Cynodon dactylon (L.) Persoon, Panicum maximum Jacq., S. viridis (L) P. Beauv, Eleusine coracana (L) Gaertner, Urochloa texana (Buckley) Webster, Sorghum sudanense Stapf, E. indica (L) Gaertner, Spodiopogon cotulifer (Thunb.) Hackel, Eragrostis cilianensis (Allioni) Vignolo-Lutati, Chloris gayana Kunth, Eragrostis curvula, Leptochloa dubia, Muhlenbergia wrightii, E. ferruginea (Thunb.) P. Beauv., Sporobolus indicus R. Br. var. purpureo -suffusus (Ohwi) T. Koyama, Andropogon gerardii, Leptochloa chinensis (L.) Nees and Zoysia tenuifolia Willd.

[0081]

[0074] Other suitable plants may include arid grasses, in one embodiment an Australian arid grass selected from the genus and / or species of: Anigozanthos, Austrodanthonia, Austrostipa, Baloskion pallens, Baumea juncea, Bolboschoenus, Capillipedium, Carex bichenoviana, Carec gaudichaudiana, Carex appressa, C. tereticaulis, Caustis, Centrolepis, Chloris truncate, Chorizandra, Conostylis, Cymbopogon, Cyperus, Desmocladus flexuosa, Dichanthium sericeum, Dichelachne, Eragrostis, Eurychorda complanata, Evandra aristata, Ficinia nodosa, Gahnia, Gymnoschoenus sphaerocephalus, Hemarthria uncinata, Hypolaeana, Imperata cylindrical, Johnsonia, Joycea pallid, Juncus, Kingia australis, Lepidosperma, Lepironia articulate, Leptocarpus, Lomandra, Meeboldina, Mesomelaena, Neurachne alopecuroidea, Notodanthonia, Patersonia, Poa, Spinifex, Themedo triandra, Tremulinatremula, Triglochin, Triodia and Zanthorrhoea. In other embodiments, arid grasses that grow in other parts of the world may also be suitable, including Aristida pallens (Wire grass), Andropogon gerardii (Big bluestem), Bouteloua eriopoda (Black grama), Chloris roxburghiana (Horsetail grass), Themeda triandra (Red grass), Panicum virgatum (Switch grass), Pennisetum ciliaris (Buffel grass), Schizachyrium scoparium (Little bluestem), Sorghatrum nutans (Indian grass) and Stipa tenacissima (Needle grass). Other grasses that may also be used in the present invention include wheat straw, Esparto (provided by Stipa tenacissima and Lygeum spartum, both Poaceae family), Oyat (the French common name for Ammophila arenaria, also from the Poaceae family), Miscanthus (which has a similar composition as T. Pungens, with a typical composition being 37.7% cellulose, 37.3% hemicellulose, 25.1 % lignin) and plants that form tumbleweeds, including fromfamilies Amaranthaceae and Chenopodiaceae, Amaryllidaceae, Apiaceae, Asphodelaceae, Asteraceae, Brassicaceae, Boraginaceae, Caryophyllaceae, Fabaceae, Lamiaceae and Poaceae.

[0082]

[0075] Hemicellulose contents as described above may be achieved by any means, including but not limited to, using plant feedstocks that are naturally high in hemicellulose and subsequent processing to produce CNFs and / or CMFs that retain a high hemicellulose content, or alternatively, using CNFs and / or CMFs that have lower hemicellulose content and mixing it with a separately produced hemicellulose material to give a mixture that provides high hemicellulose content CNFs and / or CMFs. In one embodiment, plant feedstocks with a high natural hemicellulose content include spinifex grass from the genus Triodia, Monodia, or Symplectrodia, such as a species selected from T. pungens, T. shinzii, T. basedowii and T. longiceps.

[0083]

[0076] The CNFs and / or CMFs may be obtained from a source, such as a plant source, by any suitable process. In one embodiment, the process for obtaining CNFs and / or CMFs is described in WO 2019 / 237149 A1. In one embodiment, the process for obtaining CNFs comprises a deep eutectic solvent (DES) treatment step as described more fully in WO 2023 / 028664 A1 , the entire contents of which are incorporated herein by cross-reference. In one embodiment, the DES treatment may facilitate hydrolysis of hemicellulose and extraction of lignin from the lignocellulosic structure such that the hemicellulose and lignin can be separated from the cellulose fibres. DES treatment may comprise combining dried and ground bleached pulp under a nitrogen atmosphere with a mixture of the eutectic solvent mixture of sulfamic acid and urea. In one embodiment, a molar ratio of dry pulp:sulfamic acid of about 1:10 may be used. In one embodiment, a molar ratio of acid:urea of about 1:3 may be used. The DES treatment may be conducted at a temperature of about 120 °C-170 °C, such as about 150 °C. In one embodiment, the DES-treated pulp is subjected to high pressure homogenisation (HPH) in water to produce a gelled mixture of CNFs and / or CMFs.

[0084]

[0077] In one embodiment, the CNFs and / or CMFs are extracted from a plant source, such as a plant selected from the list above, by harvesting and subsequently mulching or otherwise processing the plant leaves into short length pieces, in some embodiments into lengths of less than 10 cm, less than 7 cm, less than 5 cm, or less than 2 cm, or of from 0.1 to 10 cm, or of from 2 to 5 cm, or of from 1 to 8 cm. The leaves may then be washed, e.g., with water, to remove resins and other impurities, and then dried before grinding into fine particles, in some embodiments of about 1 mm diameter or less. The particulate material may then be subjected to a mild alkali treatment, such as with a < 5 wt% hydroxide solution at a temperature of 50 to 100 °C, followed by a bleaching step, e.g., using a chlorite salt and an acid, such as acetic acid. The washed and dried bleached pulp may then be subjected to DES treatment as described more fully in WO 2023 / 028664 A1, comprising treatment with a mixture of sulfamic acid and urea at an elevated temperature of from 120 to 170 °C before cycles of hot and cool water washes. The DES-treated pulp may then be subjected to high pressure homogenisation (HPH) in water to produce a gelled mixture of CNFs and / or CMFs.

[0085]

[0078] In certain embodiments herein, the starting material for the CNFs is an aqueous CNF gel containing 1.1 wt% CNFs. It will be appreciated that other concentration CNF gels may be used with appropriate adjustment of amounts to be used in the precursor compositions herein to form a final composition containing a suitable concentration of CNFs, or that CNF gels may be dehydrated fully toform a dry CNF starting material that is then reconstituted in water at any desired concentration before use in precursor compositions as described herein.

[0086]

[0079] The precursor composition may comprise any suitable concentration of CNFs and / or CMFs. In one embodiment, the concentration of CNFs in the precursor composition is less than 1 wt%, or less than 0.8 wt%, or less than 0.7 wt%, or less than 0.6 wt%, or less than 0.5 wt%, or less than 0.4 wt%, or less than 0.3 wt%, or less than 0.2 wt%, or of from 0.01 wt% to 1 wt%, or of from 0.1 wt% to 0.6 wt%, or of from 0.2 wt% to 0.4 wt%, or of from 0.25 wt% to 0.35 wt%, or of about 0.1 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, or 0.6 wt%. In this paragraph, wt% refers to the grams of CNFs relative to the total mass of the precursor composition, including water. A CNF concentration in the precursor composition of less than 1 wt%, and particularly of less than 0.5 wt%, advantageously allow for effective, even dispersion of CNFs in the composition and formation of swellable composites on drying that have adequate strength and film forming capabilities for use as a seed enhancement technology. In one embodiment, the concentration of CMFs in the precursor composition is less than 1 wt%, or less than 0.8 wt%, or less than 0.7 wt%, or less than 0.6 wt%, or less than 0.5 wt%, or less than 0.4 wt%, or less than 0.3 wt%, or less than 0.2 wt%, or of from 0.01 wt% to 1 wt%, or of from 0.1 wt% to 0.6 wt%, or of from 0.2 wt% to 0.4 wt%, or of from 0.25 wt% to 0.35 wt%, or of about 0.1 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, or 0.6 wt%. In a further embodiment, the combined concentration of CNFs and CMFs, where both are present is less than 1 wt%, or less than 0.8 wt%, or less than 0.7 wt%, or less than 0.6 wt%, or less than 0.5 wt%, or less than 0.4 wt%, or less than 0.3 wt%, or less than 0.2 wt%, or of from 0.01 wt% to 1 wt%, or of from 0.1 wt% to 0.6 wt%, or of from 0.2 wt% to 0.4 wt%, or of from 0.25 wt% to 0.35 wt%, or of about 0.1 wt%, 0.2 wt%, 0.25 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, or 0.6 wt%. In one embodiment, a mixture of CNFs and CMFs may be used in any suitable proportion or ratio by mass, for example, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20 or 90:10.

[0087]

[0080] The CNFs and / or CMFs herein are dispersed in the precursor composition, in one embodiment uniformly or evenly dispersed throughout the precursor composition, such as dispersed into the precursor composition by addition in the form of an aqueous, pressure homogenised gel. In one embodiment, ~1.1 wt% CNF gel is used.

[0088]

[0081] The swellable composite, for avoidance of doubt once dried, may comprise any suitable concentration of CNFs and / or CMFs. The concentration of CNFs in the dried swellable composite may be less than 60 wt%, or less than 50 wt%, or less than 40 wt%, or less than 30 wt%, or less than 20 wt%, or less than 10 wt%, or of from 10 wt% to 60 wt%, or of from 15 wt% to 50 wt%, or of from 20 wt% to 30 wt%, or of from 25 wt% to 35 wt%, or of from 20 wt% to 45 wt%, or of about 10 wt%, 20 wt%, 25 wt%, 30 wt%, 40 wt%, or 50 wt%. In this paragraph, wt% refers to the mass of CNFs relative to the total mass of solids in the swellable composite. The concentration of CMFs in the dried swellable composite may be less than 60 wt%, or less than 50 wt%, or less than 40 wt%, or less than 30 wt%, or less than 20 wt%, or less than 10 wt%, or of from 10 wt% to 60 wt%, or of from 15 wt% to 50 wt%, or of from 20 wt% to 30 wt%, or of from 25 wt% to 35 wt%, or of from 20 wt% to 45 wt%, or of about 10 wt%, 20 wt%, 25 wt%, 30 wt%, 40 wt%, or 50 wt%. The combined concentration of CNFs and CMFs in the dried swellable composite may be less than 60 wt%, or less than 50 wt%, or less than 40wt%, or less than 30 wt%, or less than 20 wt%, or less than 10 wt%, or of from 10 wt% to 60 wt%, or of from 15 wt% to 50 wt%, or of from 20 wt% to 30 wt%, or of from 25 wt% to 35 wt%, or of from 20 wt% to 45 wt%, or of about 10 wt%, 20 wt%, 25 wt%, 30 wt%, 40 wt%, or 50 wt%.

[0089]

[0082] Swellable composites comprising CNFs in a concentration of less than 40 wt% are particularly advantageous for embodiments where the swellable composite is formed into films or cellophane sheets and heat sealed. Swellable composites comprising CNF concentrations of greater than 40 wt% carry a risk of burning during heat treatment, and may instead be water sealed or formed into capsules or prills. In other embodiments, swellable composites may be formulated with CMFs. In some embodiments, a mixture of CNFs and CMFs may be used.

[0090]

[0083] Swellable composites comprising 40 wt% or more of CNFs tend to release active agents, when present, at a much slower rate and / or in a significantly lesser amount, compared to equivalent swellable composites comprising less than 30 wt% of CNFs on swelling / hydration.

[0091]

[0084] The swellable composite and precursor composition described herein comprises a water soluble polysaccharide. Any suitable water soluble polysaccharide may be used. In one embodiment, the polysaccharide is water soluble at a temperature in the range of from 5 °C to 50 °C. By virtue of its water solubility, the polysaccharides herein have a structure and composition such that a large number of hydroxide groups in particular are available for reaction and interaction with water, CNFs and / or CMFs and, if present, active agents. The water soluble polysaccharides may also contribute to the film or coating forming properties associated with the swellable composite described herein, and may assist in complexing one or more active agents for release from the swellable composite on rehydration / swelling.

[0092]

[0085] In one embodiment, the term “water soluble” refers to a solubility of the polysaccharide in water of more than 33 mg / L, or more than 50 mg / L, or more than 100 mg / L, or more than 500 mg / L, or more than 1,000 mg / L, such as of from 33 to 100 mg / L, or from 100 to 1,000 mg / L, at a temperature of 25 °C, or 30 °C, or 35 °C, or 40 °C. In one embodiment, the term “water soluble” refers to a solubility of the polysaccharide in water of more than 33 mg / L at a temperature of 25 °C. In one embodiment, the term “water soluble” refers to a solubility of the polysaccharide in water of more than 100 mg / L at a temperature of 25 °C. In one embodiment, the term “water soluble” refers to a solubility of the polysaccharide in water of more than 100 mg / L at a temperature of 40 °C.

[0093]

[0086] The water soluble polysaccharide used herein may be a linear or branched polysaccharide. In one embodiment, the water soluble polysaccharide may be a mannan composed of branched mannose monomers, or may be a galactomannan (guar gum) composed of mannose and galactose monomers, or may be a xylan composed of predominantly xylose monomers, or may be a pectin composed of predominantly galacturonic acid monomers, or may be a dextran composed of glucose monomers, or may be an arabinogalactan composed of galactose and arabinose monomers, or may be a xanthan composed of glucose, mannose and glucuronic acid monomer, or may be a pullulan composed of glucose monomers, or may be an agar comprising galactose monomers, or may be an alginate comprised of glucuronic and mannuronicacid monomers, or may be a carboxymethylcellulose (CMC) comprising modified glucose monomers, or may be an agarose comprising galactose and modified galactopyranose monomers, or may be a hyaluronic acid comprising acetylglucosamine andglucuronic acid monomers. Accordingly, in one embodiment, the water soluble polysaccharide is selected from a mannan, a galactomannan, a xylan, a pectin, a dextran, an arabinogalactan, a xanthan, a pullulan, an agar, an alginate, a carboxymethylcellulose (CMC), an agarose, and a hyaluronic acid.

[0094]

[0087] In one embodiment, the water soluble polysaccharide is a non-ionic polysaccharide. In one embodiment, a suitable non-ionic polysaccharide may be a dextran, a pullulan, an agar, or a guar gum. In one embodiment, the water soluble polysaccharide is a glucan made up of glucose monomers. In one embodiment, the glucan is a dextran or a pullulan. In one embodiment, water soluble polysaccharide is pullulan. Pullulan is a linear homo-exopolysaccharide secreted by the polymorphic yeast-like fungi Aureobasidium pullulans or A. me / anogenum. It consists of repeating maltotriose units linked with a-1,6 linkages and glucose units linked by a-1,4 glycosidic bonds, and forms linear random coil type structures. Pullulan has high chain flexibility, excellent water solubility and stability in aqueous solution.

[0095]

[0088] The water soluble polysaccharide described herein may be obtained or synthesised from any suitable source. In one embodiment, the water soluble polysaccharide is available from natural or commercial sources. Dextran, pullulan, agar, guar gum, xylan, pectin, xanthan, alginate, CMC, agarose and hyaluronic acid may all be purchased commercially from chemical suppliers and / or food companies.

[0096]

[0089] The precursor composition may comprise any suitable concentration of water soluble polysaccharide. In one embodiment, the concentration of water soluble polysaccharide in the precursor composition is less than 5 wt%, or less than 4 wt%, or less than 3 wt%, or less than 2 wt%, or less than 1 wt%, or less than 0.9 wt%, or less than 0.8 wt%, or less than 0.7 wt%, or of from 0.01 wt% to 5 wt%, or of from 0.2 wt% to 2 wt%, or of from 0.5 wt% to 1.5 wt%, or of from 0.6 wt% to 1.0 wt%, or of about 0.5 wt%, 0.75 wt%, 1.0 wt%, 1.2 wt%, 1.4 wt%, 1.6 wt%, or 2 wt%. In this paragraph, wt% refers to the mass of water soluble polysaccharide relative to the total mass of the precursor composition, including water.

[0097]

[0090] The swellable composite, for avoidance of doubt once dried, may comprise any suitable concentration of water soluble polysaccharide. The concentration of water soluble polysaccharide in the dried swellable composite may be at least 40 wt%, or at least 50 wt%, or at least 60 wt%, or at least 70 wt%, or at least 80 wt%, or at least 90 wt%, or of from 40 wt% to 90 wt%, or of from 50 wt% to 80 wt%, or of from 70 wt% to 90 wt%, or of from 60 wt% to 85 wt%, or of about 40 wt%, 50 wt%, 60 wt%, 70 wt%, 75 wt%, or 80 wt%. In this paragraph, wt% refers to the mass of water soluble polysaccharide relative to the total mass of solids in the swellable composite.

[0098]

[0091] The water soluble polysaccharide herein is dissolved in the precursor composition, such as dissolved into the precursor composition by addition into water at a ratio of 1-10 parts water soluble polysaccharide to 100 parts water before addition of the CNFs and / or CMFs.

[0099]

[0092] In one embodiment, the ratio by mass of CNFs and / or CMFs to water soluble polysaccharide in the swellable composite is of from 1:1 to 1:5, or of from 1:2 to 1:4, or of from 1:2.5 to 1: 3.5, or of about 1:3. In instances where a slower release profile of an active agent is required, a greater proportion of CNFs and / or CMFs to water soluble polysaccharide may be utilised, e.g., closer to 1:1.In instances where a quicker release profile of an active agent is required, a lesser proportion of CNFs and / or CMFs to water soluble polysaccharide may be utilised, e.g., closer to 1 :5.

[0100]

[0093] The swellable composite herein, and precursor composition, may comprise an active agent. One or more active agent(s) may be utilised in each swellable composite herein. In one embodiment, the active agent is an active agent that is known to either directly or indirectly enhance or otherwise modify seed germination, seed health, root growth and development, plant growth, plant quality, or known to either directly or indirectly control pathogens that affect seeds or plants. In one embodiment, the active agent is selected from one or more of: a plant growth regulator, a peptide, a microbe, a fungicide, and a pesticide. In one embodiment, the active agent is a combination of a plant growth regulator and a fungicide. In one embodiment, the active agent is a combination of a plant growth regulator and a microbe. In one embodiment, the active agent is a combination of a microbe and a fungicide.

[0101]

[0094] The desired concentration of any of the following active agents in the precursor compositions and swellable composites herein, such as any of the PGR, fungicides, peptides, microbes, disclosed below, can be determined by one of skill in the art for any given seed using, e.g., an agar bioassay. In such an assay, a known amount of the active agent is added to agar gel and germination rates and plant survival of seeds grown in the agar is monitored, and / or supplemented with data from pot studies when seedlings are transferred to permanent growing media / soil. Once an optimised dose has been identified as leading to the best germination rate, root development and / or seedling survival rate, it can be converted from a concentration in agar to a per seed dose. The per seed dose can then be converted into a concentration of the active agent that should be added to the precursor composition using the volume of precursor composition being used to create a dried swellable composite “dot” for one seed (e.g., from 0.25 mL to 2 mL) and the desired dose / dot, and extrapolating that to the active agent dose needed in the total composition volume. Alternatively, the area of the swellable composite cellophane / film being used to construct an envelope or packet for each seed can be used, in combination with the desired dose / packet, and extrapolated out based on the total cellophane sheet area formed from drying a given volume of precursor composition. In other embodiments, it may be preferred to determine a desired concentration for a given active agent based on supplier dosage guidelines. In some embodiments, concentration optimisation may be conducted for a particular seed / species through a process of lab or field trials.

[0102]

[0095] The compositions disclosed herein may comprise an active agent that is a plant growth regulator (PGR). Any suitable PGR may be used. In one embodiment, the PGR is a karrikin. Karrikins are a group of compounds produced during the combustion of plant material and are known for their role in promoting seed germination and plant growth. Karrikinolide (KARi; 3-methyl-2H-furo[2,3-c]pyran-2-one) and Karrikinolide-2 (KAR2; 2H-furo[2,3-c]pyran-2-one) are two known karrikins, and their structures and those of other related karrikins, KAR3-KAR6, are depicted below:

[0103]

[0104]

[0096] Other karrikins include compounds such as 3,5-dimethyl-2H-furo[2,3-c]pyran-2-one, 3,5,7-trimethyl-2H-furo[2,3-c]pyran-2-one, 5-methoxymethyl-3-methyl-2H-furo[2,3-c]pyran-2-one, 4-bromo-3,7-dimethyl-2H-furo[2,3-c]pyran-2-one, 3-methylfuro[2,3-c]pyridin-2(3H)-one, and 3,6-dimethylfuro[2,3-c]pyridin-2(6H)-one. A variety of other 2H-furo[2,3-c]pyran-2-ones and vinylogous 4H-pyrones that may be suitable active agent plant growth regulators are described in WO 2005 / 061515, the contents of which are incorporated herewith in their entirety by cross-reference. Karrikins present unique difficulties in their application to plants as not only do they degrade in light, but they have to be delivered at a precise dose in order to trigger optimum germination and growth. Delivery of suitable, controllable, and precise per seed dosage forms of karrikin compounds, such as that are capable of delivering doses as little as 1-250 ng karrikin per seed, have not been possible prior to the present invention. Previous best practice for dosing seeds with acceptably low doses of karrikins has relied on planting seeds in agar comprising a Karrikin (such as in a Petri dish), and then on-planting the germinated seedlings into soil. Karrikin compounds, such as KARi and KAR2, are available, e.g., from research chemical suppliers.

[0105]

[0097] The concentration of karrikin present in the swellable composite and precursor composition described herein may be any suitable concentration. In one embodiment, a concentration of Karrikin that enables delivery of from 0.1 ng to 5000 ng karrikin per seed is used, or of from 0.1 ng to 1 ng per seed, or of from 1 ng to 10 ng per seed, or of from 10 ng to 30 ng per seed, or of from 30 to 50 ng per seed, or of from 50 ng to 100 ng per seed, or of from 100 to 250 ng per seed, or of from 50 to 150 ng per seed, or of from 150 to 250 ng per seed, or of from 250 to 750 ng per seed, or of from 500 to 1000 ng per seed, or of from 750 to 1250 ng per seed, or of from 1000 to 2000 ng per seed, or of from 1500 to 3000 ng per seed, or of from 2000 to 4000 ng per seed, or of from 1000 to 5000 ng per seed, or of from 3500 to 5000 ng per seed, or of about 0.1, 0.5, 1, 2, 5, 10, 20, 40, 60, 80, 100, 120, 140, 160, 180, 200, 220, 250, 500, 750, 1000, 1500, 2000, 2500, 3000, 3500, 3500, 4000, 4500, or 5000 ng / seed. Optimised or desired concentrations per seed may be determined for karrikins using, e.g., an agar bioassay, as described above.

[0106]

[0098] The swellable composite described herein is not limited to karrikin as a PGR. In one embodiment, the active agent is a PGR known to be a growth inhibitor, such as paclobutrazol (PBZ), daminozide (Alar), or chlormequat chloride (CCC). In one embodiment, the active agent is a PGR known to be a growth promoter. In some embodiments, suitable growth promoters include auxins,such as indole-3-acetic acid (IAA), indole-3-butyric Acid (IBA) or naphthaleneacetic Acid (NAA), or synthetic auxins such as 2,4-dichlorophenoxyacetic acid (2,4-D), or gibberellins, such as gibberellic acid (GA3) orGA4+7, or cytokinins, such as kinetin, 6-benzylaminopurine (BAP or BA), or zeatin, ora brassinosteroid, such as 24-epibrassinolide. Many of these PGRs are available commercially.

[0107]

[0099] The PGR active agent may be added to the precursor composition in any suitable form. In some embodiments, the PGR active agent may be added directly to the precursor composition as a solid and dissolved, solubilised or dispersed in the composition. In other embodiments, the PGR active agent may be dissolved in a solvent to assist with its dissolution ordispersion in the composition, such as in an organic solvent such as a water miscible organic solvent, such as an alcohol, e.g., ethanol, or the like. In some embodiments, the PGR active agent may be prepared in aqueous solution and added to the precursor composition.

[0108]

[0100] The compositions disclosed herein may comprise an active agent that is a peptide. Any suitable peptide may be used. In one embodiment, the peptide may be a natural defensive peptide. In one embodiment, the peptide may be a cyclic peptide or “cyclotide”. Naturally occurring cyclotides are known to have plant defence properties. Numerous cyclotides have been isolated to date from plant species in the Violaceae, Poaceae, Fabaceae, Curcurbitaceae, and Rubiaceae families. In one embodiment, the cyclotide is kalata B1 (kB1) extracted and isolated from the above-ground parts of plant species Oldenlandia affinis (family Rubiaceae) according to methods known in the art.

[0109]

[0101] In one embodiment, the peptide may be a linear peptide. In one embodiment, the linear peptide may be CLE peptide, such as CLV3, a phytosulfokine or plant peptide containing sulfated tyrosine 1 (PSY1), ora systemin, ora root hair promoting peptide (RHPP), or the like. Linear peptides may be isolated from plant sources or synthesised chemically as known in the art.

[0110]

[0102] Many peptides are unstable in aqueous solution and have short half-lives. However, the swellable composites herein have proven ability to hold both linear and cyclic peptides, with reported stabilities after several days of 64% for the cyclotide (kB1) and 52% for the linear peptide RHPP when kept in the dark at room temperature within a sealed specimen jar.

[0111]

[0103] The concentration of peptide present in the swellable composite and precursor composition described herein may be any suitable concentration. In one embodiment, a concentration of stable peptide may be from 2 pg to 5 pg per seed may be used, or a concentration of stable peptide of from 2 pg to 3 pg, or of from 2.5 pg to 3.5 pg, or of from 3 pg to 5 pg, or of from 3 pg to 4.5 pg per seed may be used. In one embodiment, a stable peptide concentration of 2.6 pg to 3.2 pg peptide per seed may be used.

[0112]

[0104] In one embodiment, the peptide may have an encapsulation stability in the swellable composite of up to 99%, or up to 90%, up to 80%, up to 70%, up to 60%, or up to 50%, or of from 40 to 80%, or of from 40% to 50%, or of from 50% to 70%, or of from 50 to 99%. Accordingly, in some embodiments, more than from 2 pg to 5 pg peptide per seed may be encapsulated in the swellable composite to ensure an adequate stable peptide concentration can be delivered to each seed, such as a total amount of peptide of from 3 pg to 10 pg per seed, or of from 3 pg to 8 pg, or of from 4 pg to 6 pg, or of from 5 pg to 10 pg per seed may be encapsulated in the swellable composite to deliver a desired stable concentration of peptide per seed.

[0105] The peptide may be added to the precursor composition in any suitable form. In some embodiments, the peptide active agent may be in aqueous solution and added to the precursor composition.

[0113]

[0106] The compositions disclosed herein may comprise an active agent that is a fungicide. Any suitable fungicide may be used. Inclusion of a fungicide in the swellable composites herein advantageously allows their use with fungus-contaminated or fungal infection-susceptible seeds.

[0114]

[0107] In one embodiment, the fungicide may be a commercially available fungicide such as produced by companies including Bayer®, Corteva®, and Syngenta®. In one embodiment, suitable fungicides may include: thiram (e.g., Thiragranz®), captan (e.g., Captan WG®), carboxin (e.g., Vitavax®), metalaxyl (e.g., Evergol®), fludioxonil (e.g., Maxim®), difenoconazole (e.g., Score®), tebuconazole (e.g., Horizon 250®), azoxystrobin (e.g. Mirador® 250), triadimenol (e.g., Baytan®), thiamethoxam (Cruiser® 350 FS), mancozeb (e.g., Dithane®), pyraclostrobin (e.g., Cabrio®), sedaxane (e.g., Vibrance® CST), or penflufen (e.g., Evergol®). In one embodiment, the fungicide is formulated for application to seeds, and / or targets one or more soil-borne and / or seed-borne fungi.

[0115]

[0108] In one embodiment, the fungicide comprises a carboxamide active. In one embodiment, the fungicide comprises metalaxyl and / or prothioconazole and / or penflufen.

[0116]

[0109] The concentration of fungicide present in the swellable composite and precursor composition described herein may be any suitable concentration. In one embodiment, a concentration of fungicide that enables delivery of from 0.2 ng to 20 pg fungicide per seed, or of from 0.2 ng to 2 ng per seed, or of from 1 ng to 10 ng per seed, or of from 1 ng to 5 ng per seed, or of from 2 ng to 5 ng per seed, or of from 2 ng to 9 ng per seed, or of from 4 to 18 ng per seed, or of from 2 ng to 13 ng per seed, or of from 10 ng to 15 ng per seed, or of 0.2 ng, 0.5 ng, 1 ng, 2 ng, 5 ng, 10 ng, 13 ng, 15 ng, 17 ng, or 20 ng fungicide per seed. In one embodiment, these concentrations are per fungicide active, such when using a single fungicide or a fungicide mixture. In another embodiment, these concentrations may represent a total concentration of all fungicide actives, such as if two or more fungicide actives are used. In one embodiment, these desired concentrations are for each active in Evergol® Energy (actives: prothioconazole 7.68%, metalaxyl 6.14% and penflufen 3.84%). In one embodiment, these desired concentrations are for each active in Vibrance® CST (actives: 75 g / L azoxystrobin, 12.5 g / L fludioxonil, 75 g / L metalaxyl-M and 35 g / L sedaxane). Optimised or desired concentrations per seed may be determined for any fungicide using, e.g., a minimum inhibitory dosage assay, whereby the composite containing the fungicide active at a known concentration is placed on potato dextrose agar which has been infected with the desired pathogen.

[0117]

[0110] The fungicide active agent may be added to the precursor composition in any suitable form. In some embodiments, the fungicide active agent may be added directly to the precursor composition as a solid and dissolved, solubilised or dispersed in the composition. In some embodiments, the fungicide active agent may be in aqueous solution and added to the precursor composition. In one embodiment, the fungicide may be water soluble, such as have a water solubility of at least 5 mg / L in water, or of at least 10 mg / L in water, at 25 °C or at 40 °C. In one embodiment, the fungicide may be only partially water soluble or water insoluble. In some embodiments, the fungicide active agent maybe dissolved in a solvent to assist with its dissolution or dispersion in the composition, such as in an organic solvent such as a water miscible organic solvent, such as an alcohol, e.g., ethanol, or the like.

[0118]

[0111] The compositions disclosed herein may comprise an active agent that is a microbe. Any suitable microbe may be used. Inclusion of microbes in the swellable composites herein may advantageously provide symbiotic advantages to seeds and growing seedlings, enhance seed development, improve overall plant health, promote seed germination, enhance nutrient uptake, and / or provide protection against pathogens. Due to their size, often in the order of from 0.5 pm to 10 pm long, previous seed enhancement technologies have been unable to deliver microbes to plant seeds in the form of coatings in precise doses, and / or have been unable to maintain viability of the microbes during manufacture and storage.

[0119]

[0112] The microbes are preferably viable after incorporation into the swellable composite and precursor composition, such as maintain a viability of 100%, at least 95%, at least 90%, at least 85%, at least 80%, at least 75%, or at least 50% after incorporation into the swellable composite and precursor composition, or maintain a viability of 100%, at least 95%, at least 90%, at least 85%, at least 80%, at least 75%, or at least 50% in the swellable composite.

[0120]

[0113] In one embodiment, the microbe is a plant growth promoting microorganism (PGPM). In one embodiment, the microbe comprises a plant growth promoting rhizobacteria (PGPR) microbe. PGPR microbes colonise the region of soil surrounding plant roots, where they exert beneficial effects on plants through direct and indirect mechanisms. Common PGPR microbes include Azospirillum, Bacillus, and Pseudomonas spp.

[0121]

[0114] In one embodiment, the microbe is a PGPR microbe capable of nitrogen fixing. Some examples of nitrogen fixing microbes are Rhizobium, Sinorhizobium, Azorhizobium, Allorhizobium, Mesorhizobium, Bradyrhizobium, Burkholderia, and Herbaspirillum spp. In one embodiment, the nitrogen fixing microbe is Rhizobium spp., a genus of gram-negative soil-derived bacteria that fix atmospheric nitrogen for leguminous plants. Commercial sources of rhizobia bacteria include Nitragin Gold® (Novozymes®). In one embodiment, the PGPR is Bradyrhizobium diazoefficiens strain USDA110. In another embodiment, the nitrogen fixing microbe is Azospirillum spp., which is a genus of gram negative bacteria that fix nitrogen and enhance root growth. Azospirillum spp. are commercially available as Azospirillum Brasilense, Azos Red® (Xtreme Gardening®).

[0122]

[0115] In one embodiment, the microbe is a PGPR having a non-nitrogen fixing function. In one embodiment, the non-nitrogen fixing microbe is Bacillus spp. or Pseudomonas spp. In one embodiment, the microbe is Bacillus spp., which includes Bacillus subtilis, a genus of bacteria known for hormone and enzyme production. Bacillus spp. is commercially available in formulations such as Companion® (Growth Products Ltd.) and Serenade® (Bayer Crop Science). In one embodiment, the microbe is Pseudomonas spp., which includes P. aeruginosa, P. chlororaphis, P. fluorescens, P. putida, and P. syringe, are a genus of bacteria that promote root growth and provide biocontrol, and is available commercially in, e.g., Proradix® (Sourcon-Padena GmbH).

[0123]

[0116] In one embodiment, the microbe is a beneficial fungus. In one embodiment, the fungus is a mycorrhizal fungus, Trichoderma spp. or Penicillium bilaiae. In one embodiment, the microbe is Trichoderma spp., such as Trichoderma harzianum, Trichoderma lignorum or Trichoderma koningii,which promote plant growth and protect against soil-borne pathogens. Commercially available sources of Trichoderma spp. include Rootshield® (BioWorks Inc.), Trichodry® (Agrimm Technologies Ltd) and Tricho-Shield® (Nutri-Tech Solutions Pty Ltd). In one embodiment, the microbe is a mycorrhizal fungus, including endo / arbuscular and ecto mycorrhiza I fungi such as from the phyla Glomeromycota, Ascomycota or Basidiomycota, and are known for their role in extending the root system of plants to improve water and nutrient uptake. Commercial sources of mycorrhizal fungi include MycoApply® (Valent BioSciences®). In one embodiment, the microbe is Penicillium bilaiae, which is a native species of soil fugus that solubilises phosphate to enhance root development. Commercial products such as JumpStart® (Novozymes) comprise Penicillium bilaiae.

[0124]

[0117] In one embodiment, the microbe is selected from rhizobia bacteria, mycorrhizal fungi, Trichoderma spp., Azospirillum spp., Bacillus spp., Pseudomonas spp., and Penicillium bilaiae.

[0125]

[0118] The concentration of microbes present in the swellable composite and precursor composition described herein may be any suitable concentration. In one embodiment, a concentration of microbes that enables delivery of from 1 CFU to 1 x 109CFU microbes per seed is used, or of from 1 x 106CFU to 1 x 109CFU, or of 1 x 10'3propagule to 1 x 102propagules per seed is used. Optimised or desired concentrations per seed may be determined for any microbe using spectrophotometric (turbidimetric) techniques.

[0126]

[0119] In one embodiment, the swellable composites and precursor compositions described herein may comprise one or more additional components. In one embodiment, the additional component may alter the film-forming properties of the swellable composite, and / or may alter its appearance. In one embodiment, the additional component may be selected from a filler, a plasticiser, a film-forming agent, a surfactant, a dye and / or a pigment. In one embodiment, the additional component may prolong the life of the swellable composite, such as may be a preservative. In one embodiment, the additional component may be a nutrient. Suitable fillers, plasticisers, film-forming agents, surfactants, dyes, pigments, preservatives, and nutrients will be known to those of skill in the art.

[0127]

[0120] The swellable composites herein containing an active agent may release that active agent on hydration. Accordingly, in one embodiment, the swellable composites are controlled release swellable composites. In one embodiment, the controlled release swellable composites are hydration-activated. In one embodiment, the hydration is provided by water. In one embodiment, the water is fresh water, that is, free or substantially free of dissolved salts / ions. The water may be any suitable water, including but not limited to, municipal water, bore water, ground water, dam water, rain water, or surface water (creek, river, lake, etc.), or the like. Without wishing to be bound by theory, hydration of the swellable composite expands the gel structure and allows the active agent to be solubilised and / or released through changes in intermolecular interactions. Although the swellable composites herein may have any suitable hydratability or swellability, in one embodiment, the swellable composites herein have a swellability, in one embodiment in water, of at least 10,000% after a period of 30 min. In one embodiment, the swellable composites herein have a maximum swellability, in one embodiment in water, of at least 10,000% after a period of 30 min, or of at least 12,000% after a period of 30 min, or at least 14,000% after a period of 30 min. In one embodiment, the swellable composites herein have a maximum swellability, in one embodiment in water, of at least 16,000% after a period of 60 min, orof at least 18,000% after a period of 60 min, or at least 20,000% after a period of 60 min. In one embodiment, the swellable composites herein have a maximum swellability, in one embodiment in water, of at least 2,000% after a period of 1 min, or of at least 3,000% after a period of 1 min, or at least 5,000% after a period of 2 min. In one embodiment, the swellable composites herein have a maximum swellability, in one embodiment in water, of from 4,000% to 10,000% after a period of 30 min, or of at least 6,000% to 12,000% after a period of 30 min, or at least 8,000% to 14,000% after a period of 30 min. It has been found that these swellabilities advantageously allow for adequate active agent release. However, without wishing to be bound by theory, these swellabilities may also offer other advantages, such as retention of water around the growing seed, that assist in the methods and uses described herein, such as enhancing seed viability, seed germination, root development and / or plant growth. In one embodiment, the swellabilities in this paragraph are measured at room temperature, such as at 25 °C.

[0128]

[0121] In one embodiment, the swellability of the swellable composite, also referred to variously as volume variation (%), and “swelling ratio”, is calculated as follows:

[0129] [(wf-w / ) / (w / )] x 100

[0130] where w / = weight of the dry composite, and wt= weight of the wetted / swelled composite at time t.

[0131]

[0122] In one embodiment, the swellable composite forms a (dry) film that is flexible, such as is capable of bending 90°, or bending 120°, or bending 180°, without cracking or breaking. In one embodiment, the swellable composite forms a coherent film. In one embodiment, the swellable composite forms a film that is dry. In one embodiment, the dry swellable composite film may comprise less than 5 wt% water, less than 2.5 wt% water, less than 1 wt% water, less than 0.5 wt% water, or less than 0.1 wt% water.

[0132]

[0123] The swellable composite, or film, prill or capsule thereof, may have any suitable thickness, but in some embodiments, has a thickness of up to 3 mm, or of up to 2 mm, or of up to 1 mm, or of up to 750 pm, or of up to 500 pm, or of up to 250 pm, or of up to 100 pm, or of up to 50 pm, or of up to 30 pm, or of at least 10 pm or of at least 25 pm, or of at least 30 pm, or of at least 50 pm, or of at least 100 pm, or of from 10 pm to 100 pm, or of from 20 pm to 50 pm, or of from 30 pm to 150 pm, or of from 10 pm to 500 pm, or of from 10 pm to 1 mm, or of from 1 m to 3 mm. In some embodiments, the swellable composite may comprise more than one layer. In some embodiments, the swellable composite may be in the form of a single layer.

[0133]

[0124] Described herein is a method of producing a precursor composition, comprising mixing a water soluble polysaccharide, cellulose nanofibres (CNFs) and / or cellulose microfibres (CMFs), and optionally an active agent, in water. In some embodiments, the CNFs are pre-dispersed in water in the form of, e.g., a gel, such as a 1.1 wt% gel, that is the product of deep eutectic solvent and high pressure homogenisation treatment of plant material and that produces high quality nanofibrillated cellulose as described elsewhere and elsewhere herein. In one embodiment, the water soluble polysaccharide is dissolved in water prior to mixing with the CNFs and / or CMFs, optionally the CNF gel. In one embodiment, the active agent is added after mixing of the CNFs and the polysaccharide together. In one embodiment, the mixing is performed at room temperature, such as 25 °C, or undergentle heating, such as to 30 °C. In one embodiment, mixing is performed until each or all components are visibly dissolved.

[0134]

[0125] Also described herein is a method of producing a swellable composite for enhancing seed germination, comprising providing a precursor composition comprising a water soluble polysaccharide, cellulose nanofibres (CNFs) and / or cellulose microfibres (CMFs), and optionally an active agent, in water; applying a quantity of the precursor composition to a surface; and allowing the precursor composition to dry on the surface, thereby forming the swellable composite.

[0135]

[0126] In one embodiment, the precursor composition is produced by the method described above. In one embodiment, the quantity of the precursor composition applied to a surface is selected from 0.1 mL to 0.5 mL for the purpose of manufacturing prills, from 0.5 mL to 2.0 mL for the purpose of manufacturing cellophane or film “dots”, and larger volumes for the purpose of manufacturing sheets. Any suitable surface may be used, but preferably the surface is a non-stick surface. In one embodiment, the surface is a Teflon-coated surface, a glass surface or a silicon surface. In one embodiment, the surface is Teflon-coated. In one embodiment, the surface is flat or substantially flat, preferably where dots, prills, or a cellophane or film is required. In one embodiment, the surface is shaped, such as is a mould. In such embodiments, it is possible to form three-dimensional capsules and the like. In one embodiment, a mould may be filled. In such embodiments, it may be possible to form three-dimensional pellets or prills or the like. In one embodiment, allowing the precursor composition to dry comprises exposing the precursor composition to atmospheric conditions, such as laboratory conditions, e.g., 25 °C and humidity of less than 80%, or comprises exposing the precursor composition to a dry atmosphere, or comprises using an air flow to accelerate drying.

[0136]

[0127] Described herein is a method of enhancing seed viability, seed germination, root development and / or plant growth, comprising priming a seed with a precursor composition as described herein. In one embodiment, the method is of enhancing seed viability. In one embodiment, the method is of enhancing seed germination. In one embodiment, the method is of enhancing root development, including root nodule development. In one embodiment, the method is of enhancing plant growth.

[0137]

[0128] In one embodiment, the method comprises wet priming a seed. In one embodiment, priming a seed comprises immersing it in the precursor composition for a period of time, such as for 4 h to 48 h, and then sowing the seed while the precursor composition is still wet. This method is particularly suitable for fresh seeds, or seeds that are less or not susceptible to, or not suffering from, fungal infection.

[0138]

[0129] In one embodiment, the method comprises in situ wet priming a seed. In one embodiment, in situ wet priming a seed comprises injecting a volume of precursor composition onto the seed in situ in planting medium.

[0139]

[0130] In another embodiment, the method comprises wet / dry priming. In one embodiment, wet / dry priming comprises priming the seed, such as immersing it in the precursor composition fora period of time, such as for 4 h to 48 h, or injecting a volume of precursor composition onto the seed, and then allowing the seed with the precursor composition coated on it to dry. This results in formation of a dried layer of swellable composite around the seed. The dry coated dried seed may then subsequentlybe planted. This method is particularly suitable for fresh seeds, or seeds that are less or not susceptible to, or not suffering from, fungal infection.

[0140]

[0131] In another embodiment, there is described a method of enhancing seed viability, seed germination, root development and / or plant growth, comprising co-planting a seed with or within a swellable composite as described herein. In one embodiment, the method is of enhancing seed viability. In one embodiment, the method is of enhancing seed germination. In one embodiment, the method is of enhancing root development, including root nodule development. In one embodiment, the method is of enhancing plant growth. In one embodiment, in the method of enhancing plant growth, the swellable composite is co-planted with a seed. However, it will be appreciated that in other embodiments, the swellable composite may be co-planted with a germinated seedling and / or with a cutting. Accordingly, in one aspect, described herein is a method of enhancing root development and / or plant growth, comprising: co-planting a germinated seedling or a cutting with a swellable composite as described herein, and applying water to the swellable composition to cause it to swell. In such embodiments, the germinated seedling and / or cutting may be co-planted above, beside, or below a prill or sheet of the swellable composite. In such embodiments, the roots of the germinated seedling and / or the node or base of the cutting or roots emerging therefrom may be in contact with a surface of the swellable composite prill or sheet, or may otherwise be immediately adjacent to the swellable composite prill or sheet, such that upon hydration, the swelled swellable composite makes contact with the roots of the germinated seedling and / or the node or base of the cutting or roots emerging therefrom. It will also be appreciated that references to uses of and methods using the swellable composite (and precursor composition) described herein described with reference to use with seeds may, in certain embodiments, also be applicable to use with germinated seedlings and / or cuttings. A person of skill in the art will readily be capable of adapting the size, shape and / or coating method described herein, for the swellable composite and / or the precursor composition described with reference to seeds, to germinated seedlings and / or cuttings.

[0141]

[0132] In one embodiment, co-planting comprises wrapping, packaging, or encapsulating a seed within a swellable composite film or cellophane wrap, coating, package or capsule. In one embodiment, co-planting comprises wrapping a seed with a swellable composite film wrapper, or cellophane wrap or dot. In some embodiments, a single layer of swellable composite is used to wrap seeds. In one embodiment, co-planting comprises packaging a seed in a swellable composite packaging, such as an envelope, packet, or similar. In one embodiment, the envelope, packet or similar is created from a folded layer of swellable composite or is formed from two or more sheets of swellable composite that are heat sealed, water sealed, or folded so as to create the packaging. In one embodiment, co-planting comprises encapsulating a seed in a capsule made of swellable composite. The capsule may comprise two parts that fit together to encapsulate the seed. In one embodiment, co-planting comprises planting a seed above, beside or below a prill of the swellable composite. In such embodiments, the seed may be in contact with a surface of the swellable composite prill, or may otherwise be immediately adjacent to the swellable composite prill such that upon hydration, the swelled swellable composite makes contact with the seed. In one embodiment, more than one layer of swellable composite may be used to construct a prill, such as 2 or more layers,or 5 or more layers. In one embodiment, each layer is dried before the next layer is added. In one embodiment, the layers are heat sealed together. In one embodiment, the layers are water sealed together. In one embodiment, each layer is identical. In one embodiment, the layers may be different, such as a different precursor composition / swellable composite is used for some or all layers. In such a way, a release profile may be created for delivery of actives at different times and / or in different concentrations and / or in different directions in the one swellable composite prill. In one embodiment, the prill comprises a solid dried mass.

[0142]

[0133] Accordingly, also described herein is use of a precursor composition as described herein for enhancing seed viability, seed germination, root development and / or plant growth. Also described herein is use of a swellable composite as described herein for enhancing seed viability, seed germination, root development and / or plant growth. Also described herein is use of a prill, film, wrap, package or capsule of swellable composite as described herein forco-planting with a seed to enhance seed viability, seed germination, root development and / or plant growth. The method may comprise the step of applying water to the swellable composition to cause it to swell. The swellable composition may swell by any suitable percent. It will be understood that on swelling, the swellable composition may initially absorb or hold water, which it then gradually releases, and if active agents are present, may gradually release the active agents to the seed also. In this way, release of active agents to the seed may be controlled by timing the application of water and therefore swelling and active agent release from the swellable composite. Also described herein is use of a swellable composite as described herein as a tissue culture medium. In preferred embodiments, the swellable composite is swelled or hydrated in use, optionally for the duration of use. In one embodiment, the tissue culture medium comprising or consisting of a swellable composite as described herein may be used as a tissue culture medium for growing seeds. In other embodiments, the tissue culture medium comprising or consisting of a swellable composite as described herein may be used as a tissue culture medium for growing seedlings and / or cuttings. In one embodiment, the tissue culture medium comprising or consisting of a swellable composite as described herein may be used as a tissue culture medium for growing seeds, seedlings and / or cuttings.

[0143]

[0134] In the uses and methods described herein, the seed may be any suitable seed. In one embodiment, the seed is of a commercially significant plant, such as soybean, wheat, cotton, rice, barley, oats, sorghum, canola (rapeseed), sunflower, sugarcane, oil palm, cassava, or the like. In one embodiment, the seed is fora leguminous plant, such as soybean, peanut, bean, chickpea, or lentil.

[0144]

[0135] In another embodiment, the seed is an Australian native plant seed. In one embodiment, the seed is an Australian native plant seed categorised as being hard to germinate by Greening Australia Ltd. In one embodiment, the seed is from an Australian native plant in a family such as Myrtaceae, Proteaceae, Fabaceae, Haemodoraceae, Rutaceae, Ericaceae, Goodeniaceae, Asteraceae, Casuarinaceae, Asparagaceae, Poaceae, Apocynaceae, Solanaceae, Santalaceae, and Cunoniaceae. In one embodiment, the seed may be for a plant belonging to the Solanaceae family, Goodeniaceae family, Dilleniaceae family, or Myrtaceae family. Suitable examples of seeds for use with the swellable composite and precursor compositions described herein include Solanum orbiculatum (wild tomato; Solanaceae family), Scaevola albida (pale fan flower; Goodeniaceae family),regarded by Greening Australia as hard to germinate, Hibbertia diffusa (Wedge guinea flower, Dilleniaceae family), which is a species with a hard seed coat that is regarded by Greening Australia as difficult to germinate and grow, and Lepostermum erubescens (roadside tea tree, Myrtaceae family), which has tiny (dust-like) seeds that do not emerge in soil, and which Greening Australia regard as difficult to grow.

[0145] Embodiments

[0146]

[0136] Embodiment 1. A precursor composition, comprising: cellulose nanofibres (CNFs) and / or cellulose microfibres (CMFs); a water soluble polysaccharide; optionally, an active agent; and water.

[0147]

[0137] Embodiment 2. The precursor composition of Embodiment 1 , comprising an active agent.

[0148]

[0138] Embodiment 3. The precursor composition of Embodiment 1 or Embodiment 2, wherein the CNFs and / or CMFs are present at a concentration of less than 1 wt%, optionally of from 0.1 wt% to 0.6 wt%, preferably of from 0.2 wt% to 0.4 wt%, optionally wherein the CNFs and / or CMFs are dispersed in the precursor composition.

[0149]

[0139] Embodiment 4. The precursor composition of any one of the preceding Embodiments, wherein the water soluble polysaccharide is present at a concentration of less than 5 wt%, optionally of from 0.01 wt% to 5 wt%, preferably of from 0.5 wt% to 1.5 wt%.

[0150]

[0140] Embodiment 5. The precursor composition of any one of the preceding Embodiments, wherein the water is present in an amount of at least 95 wt%, optionally at least 98 wt%.

[0151]

[0141] Embodiment 6. A swellable composite for enhancing seed germination, comprising: cellulose nanofibres (CNFs) and / or cellulose microfibres (CMFs); a water soluble polysaccharide; and optionally, an active agent.

[0152]

[0142] Embodiment 7. The swellable composite of Embodiment 6, comprising an active agent, preferably wherein the active agent is for controlled release on swelling of the swellable composite in water, optionally wherein the swellable composite has a swellability of at least 10,000% after a period of 30 min immersion in water at 25°C.

[0153]

[0143] Embodiment 8. The swellable composite of Embodiment 6 or Embodiment 7, in the form of a film, a prill, ora capsule, optionally that is dry, preferably comprising <1 wt% water.

[0154]

[0144] Embodiment 9. The swellable composite of any one of Embodiments 6 to 8, comprising less than 60 wt%, optionally of from 10 wt% to 60 wt% CNFs and / or CMFs, preferably of from 20 wt% to 45 wt% CNFs and / or CMFs.

[0155]

[0145] Embodiment 10. The swellable composite of any one of Embodiments 6 to 9, comprising least 40 wt%, optionally of from 40 wt% to 90 wt% water soluble polysaccharide, preferably of from 55 wt% to 80 wt% water soluble polysaccharide.

[0156]

[0146] Embodiment 11. The swellable composite of any one of Embodiments 6 to 10, that is a filmforming swellable composite.

[0157]

[0147] Embodiment 12. The precursor composition or swellable composite of any one of the preceding Embodiments, wherein the CNFs have a diameter of from 1 to 20 nm, a length of from 500 to 2,500 nm, and an aspect ratio of from 200 to 1,000, optionally wherein the CNFs are obtained from a spinifex grass within the genera Triodia, Monodia, or Symplectrodia, preferably wherein the CNFs are sourced from T. pungens, T. shinzii, T. basedowii or T. longiceps.

[0148] Embodiment 13. The precursor composition or swellable composite of any one of the preceding Embodiments, wherein the CNFs are obtained in a process comprising deep eutectic solvent treatment and high pressure homogenisation.

[0158]

[0149] Embodiment 14. The precursor composition or swellable composite of any one of the preceding Embodiments, wherein the water soluble polysaccharide has a solubility in water of at least than 33 mg / L at a temperature of 25 °C, preferably of more than 100 mg / L at a temperature of 25 °C.

[0159]

[0150] Embodiment 15. The precursor composition or swellable composite of any one of the preceding Embodiments, wherein the water soluble polysaccharide is selected from a mannan, a galactomannan, a xylan, a pectin, a dextran, an arabinogalactan, a xanthan, a pullulan, an agar, an alginate, a carboxymethylcellulose (CMC), an agarose, and a hyaluronic acid, or a combination thereof.

[0160]

[0151] Embodiment 16. The precursor composition or swellable composite of any one of the preceding Embodiments, wherein the water soluble polysaccharide is a non-ionic polysaccharide, optionally wherein the non-ionic polysaccharide is selected from a dextran, a pullulan, an agar, and a guar gum, or a combination thereof, or is a glucan, optionally wherein the glucan is a dextran or a pullulan.

[0161]

[0152] Embodiment 17. The precursor composition or swellable composite of any one of the preceding Embodiments, wherein the dispersed CNFs and / or CMFs and water soluble polysaccharide are present in a mass ratio of CNFs and / or CMFs:polysaccharide of from 1:1 to 1:5, optionally of from 1:2 to 1:4, preferably of from 1:2.5 to 1:3.5.

[0162]

[0153] Embodiment 18. The precursor composition or swellable composite of any one of the preceding Embodiments, wherein the active agent is selected from one or more of: a plant growth regulator, a peptide, a microbe, a fungicide, and a pesticide, optionally wherein the active agent comprises a plant growth regulator and / or a microbe and / or a fungicide.

[0163]

[0154] Embodiment 19. The precursor composition or swellable composite of any one of the preceding Embodiments, wherein the active agent is a plant growth regulator, optionally a plant growth regulator selected from a karrikin and a plant growth promoter such as an auxin, a gibberellin, a cytokinin, a brassinosteroid, or zeatin.

[0164]

[0155] Embodiment 20. The precursor composition or swellable composite of any one of the preceding Embodiments, wherein the active agent is a plant growth regulator and is present in the precursor composition in a concentration sufficient to provide from 0.1 ng to 5000 ng of the active agent per seed.

[0165]

[0156] Embodiment 21. The precursor composition or swellable composite of any one of the preceding Embodiments, wherein the active agent is a peptide, optionally selected from a linear peptide or a cyclotide, preferably wherein the linear peptide is a CLE peptide, a systemin, or a root hair promoting peptide (RHPP) or the cyclotide is kalata B1.

[0166]

[0157] Embodiment 22. The precursor composition or swellable composite of any one of the preceding Embodiments, wherein the active agent is a peptide and is present in the precursor composition in a concentration sufficient to provide from 2 pg to 5 pg stable peptide per seed.

[0158] Embodiment 23. The precursor composition or swellable composite of any one of the preceding Embodiments, wherein the active agent is a fungicide, preferably wherein the fungicide is formulated for application to seeds and / or targets one or more soil-borne and / or seed-borne fungi, optionally wherein the fungicide is selected from one or more of: thiram, captan, carboxin, metalaxyl, fludioxonil, difenoconazole, tebuconazole, azoxystrobin, thiamethoxam, triadimenol, mancozeb, pyraclostrobin, sedaxane, and penflufen.

[0167]

[0159] Embodiment 24. The precursor composition or swellable composite of any one of the preceding Embodiments, wherein the active agent is a fungicide and is present in the precursor composition in a concentration sufficient to provide from 0.2 ng to 18 ng fungicide per seed.

[0168]

[0160] Embodiment 25. The precursor composition or swellable composite of any one of the preceding Embodiments, wherein the active agent is a microbe or plant growth promoting microorganism (PGPM), optionally wherein the PGPM is a plant growth promoting rhizobacteria (PGPR) or a beneficial fungus.

[0169]

[0161] Embodiment 26. The precursor composition or swellable composite of any one of the preceding Embodiments, wherein the active agent is a microbe is a plant growth promoting rhizobacteria (PGPR) selected from a nitrogen fixing PGPR selected from one or more of the genera Rhizobium, Sinorhizobium, Azorhizobium, Allorhizobium, Mesorhizobium, Bradyrhizobium, Burkholderia, and Herbaspirillum spp., preferably from the genera Rhizobium’, and a non-nitrogen fixing PGPR selected from the genera Bacillus spp. and / or Pseudomonas spp, or is a beneficial fungus selected from a mycorrhizal fungus from the phyla Glomeromycota, Ascomycota or Basidiomycota, a Trichoderma spp., or Penicillium bilaiae.

[0170]

[0162] Embodiment 27. The precursor composition or swellable composite of any one of the preceding Embodiments, wherein the active agent is a microbe and is present in the precursor composition in a concentration sufficient to provide from 1 x 106to 1 x 109CFU microbes per seed.

[0171]

[0163] Embodiment 28. The precursor composition or swellable composite of any one of the preceding Embodiments, comprising cellulose nanofibres (CNFs).

[0172]

[0164] Embodiment 29. A swellable composite according to any one of Embodiments 6 to 28 when made from a precursor composition according to any one of Embodiments 1 to 5 or 12 to 27.

[0173]

[0165] Embodiment 30. A method of enhancing seed viability, seed germination, root development and / or plant growth, comprising: priming a seed with a precursor composition according to any one of Embodiments 1 to 5 or 12 to 28.

[0174]

[0166] Embodiment 31. The method of Embodiment 30, wherein the method comprises wet priming the seed and sowing the seed while the precursor composition is still wet, or wet / dry priming, that is, priming the seed with precursor composition, allowing the seed with the precursor composition coating to dry to form a dried layer of swellable composite around the seed, and subsequently planting the dried seed with the swellable composite coating.

[0175]

[0167] Embodiment 32. A method of enhancing seed viability, seed germination, root development and / or plant growth, comprising: co-planting a seed with or within a swellable composite according to any one of Embodiments 6 to 28, and optionally applying water to the swellable composition to cause it to swell.

[0168] Embodiment 33. The method of Embodiment 32, wherein co-planting comprises wrapping, packaging, or encapsulating the seed within a swellable composite film or cellophane wrap, package or capsule, or comprises planting the seed adjacent to a prill of the swellable composite.

[0176]

[0169] Embodiment 34. The method of any one of Embodiments 30 to 33, wherein the seed is a commercially significant plant seed, optionally selected from soy, wheat, cotton, rice, barley, oats, sorghum, canola (rapeseed), sunflower, sugarcane, oil palm, and cassava, for a leguminous plant, optionally selected from soybean, peanut, bean, chickpea, and lentil, or an Australian native plant seed, optionally selected from the Myrtaceae, Proteaceae, Fabaceae, Haemodoraceae, Rutaceae, Ericaceae, Goodeniaceae, Asteraceae, Casuarinaceae, Asparagaceae, Poaceae, Apocynaceae, Solanaceae, Santalaceae, and Cunoniaceae families.

[0177]

[0170] Embodiment 35. The method of any one of Embodiments 30 to 34, wherein the swellable composite comprises an active agent, and wherein the active agent is a plant growth regulator and is present in the swellable composite at a concentration of from 0.1 ng to 5000 ng of the active agent per seed, or wherein the active agent is a peptide and is present in the swellable composite at a concentration of from 2 pg to 5 pg stable peptide per seed, or wherein the active agent is a fungicide and is present in the swellable composite at a concentration of from 0.2 ng to 18 ng fungicide per seed, or wherein the active agent is a microbe and is present in the swellable composite at a concentration of from 1 x 106 to 1 x 109 CFU microbes per seed.

[0178]

[0171] Embodiment 36. Use of a swellable composite according to any one of Embodiments 6 to 28 as a plant tissue culture medium, optionally wherein the swellable composite is swelled or hydrated in use.

[0179]

[0172] Embodiment 37. A method of producing a precursor composition, comprising: mixing a water soluble polysaccharide, cellulose nanofibres (CNFs) and / or cellulose microfibres (CMFs), and optionally an active agent, in water.

[0180]

[0173] Embodiment 38. A method of producing a swellable composite for enhancing seed germination, comprising: providing a precursor composition comprising a water soluble polysaccharide, cellulose nanofibres (CNFs) and / or cellulose microfibres (CMFs), and optionally an active agent, in water; applying a quantity of the precursor composition to a surface; and allowing the precursor composition to dry on the surface, thereby forming the swellable composite.

[0181]

[0174] Embodiment 39. A method of enhancing root development and / or plant growth, comprising: co-planting a germinated seedling or a cutting with a swellable composite according to any one of Embodiments 6 to 28, and optionally applying water to the swellable composition to cause it to swell.

[0182]

[0175] Embodiment 40. A method of enhancing root development and / or plant growth, comprising: priming a germinated seedling or a cutting with a precursor composition according to any one of Embodiments 1 to 5 or 12 to 28, optionally wherein the method comprises wet priming one or more roots of the germinated seedling or cutting, or a base or node of the cutting, with the precursor composition and planting the germinated seedling or cutting while the precursor composition is still wet, or wet / dry priming, that is, priming one or more roots of the germinated seedling or cutting, or a base or node of the cutting, with precursor composition, allowing the precursor composition to dry to form a dried layer of swellable composite around the one or more roots of the germinated seedling orcutting, or a base or node of the cutting, and subsequently planting the dried germinated seedling or cutting with the swellable composite coating.

[0183] Examples

[0184] 1 - Preparation of swellable composite and precursor solutions

[0185] 1.1 - Preparation of cellulose nanofibres (CNFs)

[0186]

[0176] Spinifex grass (Triodia pungens) was collected from Camooweal in Queensland, Australia. NaOH flake (98% purity) was purchased from Alfa Aesar. Calcofluor white was obtained from Sigma-Aldrich. Reverse osmosis (RO) purified water was used throughout.

[0187]

[0177] Baled spinifex grass leaves, preferably harvested from the spinifex grass without the stem portion and without seeds, were separated into clumps and trimmed to remove residual woody stems, leaving primarily pulpable leaf material. This material was then mulched to a nominal length of 20-50 mm. Alternatively, spinifex grass leaves were fed into a Brentwood AZ5 shredder, which processed the material into smaller pieces suitable for further treatment.

[0188]

[0178] The mulched grass was then washed to remove resin and other impurities. This involved placing the grass in a double-jacketed vessel filled with hot water (approximately 80 °C) at a ratio of approximately 1 part grass to 50 parts water and stirring it for about 45 min to 1 % ours per cycle, skimming off the floating resin layer if required. Typically, three to six cycles were required, depending on the resin content and the mass of the charge. After washing, the grass was dried to <~1% moisture in an oven (approximately 65 °C) for three to five days. The material was periodically turned to ensure even drying. Once dried, the grass was ground at 1500-3000 RPM using a SM300 mill (Retsch, Germany) equipped with a 1 mm or 0.5 mm screen. The dry grinding process reduced the material to fine, uniform particles.

[0189]

[0179] The ground material was then treated in a 3 wt% sodium hydroxide solution at 80°C for two hours to delignify it. The delignified pulp was thoroughly washed in water (approximately 65 °C, 3-6 60 min cycles) to eliminate residual chemicals. The pulp was then resuspended in water and bleached for further purification at approximately 70 °C using sodium chlorite (to 1 wt% based on water content of solution) for 5 min, and then glacial acetic acid added to achieve a pH of approximately 4. The reaction was then left for one hour, filtered, and then repeated again. The bleached pulp was washed with hot water to remove remaining bleaching agents.

[0190]

[0180] Next, the bleached pulp was dried and ground and subjected to deep eutectic solvent (DES) treatment. Without wishing to be bound by theory, DES treatment is thought to facilitate hydrolysis of hemicellulose and extraction of lignin from the lignocellulosic structure by disrupting bonds connecting the lignin and hemicellulose to each other and cellulose fibres, where the higher solubility of hemicellulose and lignin in DESs compared to cellulose allows for their separation from the cellulose fibres. The process of DES treatment is described more fully in WO 2023 / 028664 A1 , the entire contents of which are incorporated herein by cross-reference. In summary, DES treatment comprised combining the dried and ground bleached pulp (molar ratio of dry pulp:sulfamic acid of 1:10) under a nitrogen atmosphere with a mixture of sulfamic acid and urea (molar ratio acid:urea of 1:3, premixed for 2 h at 80 °C) at 150 °C for 30 minutes. The pulp was then suspended / washed in boiling water,centrifuged at 4500 RPM for 20 min (repeated for four cycles), and then resuspended in room temperature water and centrifuged (repeated for four cycles).

[0191]

[0181] The DES-treated pulp was then subjected to high pressure homogenisation (HPH) to produce a CNF gel. HPH was performed on Panther NS3006L or PandaPlus 2000 pilot scale high pressure homogenizer (GEA Niro Soavi, Italy) at a solid content of approximately 0.5% (w / v), ensuring a final volume of 2 L water for 10 g of bleached pulp. Material was passed through the homogenizer at 400 barG, 700 barG and subsequently three times at 1100 barG. The resultant mixtures were then centrifuged (4500 RPM 15-30 min per cycle) to concentrate the CNF into a gel for further use (target 1.1 wt% gel) and refrigerated in an opaque container until use. Alternatively, when powdered CNF was desired, the resultant mixtures were freeze dried for 4-5 days before reconstitution and use.

[0192]

[0182] The CNFs produced by this method had a very high aspect ratio, ranging from 266 to 958 (527 ± 185), primarily due to a very thin diameter of 1 -8 nm (see Figure 1 , average diameter 3.5 ± 0.8 nm; average length 1686 ± 591 nm).

[0193] 1.2 - Preparation of precursor composition

[0194]

[0183] Without active agent: MilliQ water was added to powdered pullulan (Xi'an Waycoo Industrial & Trading Co., Ltd) (weight ratio watecpullulan = 100:1, e.g., 0.42 g pullulan in 42 mL water) with stirring, optionally with gentle heating to ~30 °C. Once dissolved / the solution was clear, a 1.1 wt% mixture of CNFs in aqueous solution (13 mL CNF gel per 42 mL water) was added with stirring to produce a ~0.26 wt% CNF solution. Once dried, the CNF content of this solution was ~25 wt%. This composition (Composition / Composite A in Table 1 below) was used to make cellophane dots, prills and cellophane sheets as described below and denoted “B-Tech” in various examples and Figures herein. Active agents present in the B-Tech / composite are indicated after the word “B-Tech” and synthesised as described in sections 1.2.1-1.24 below.

[0195]

[0184] Alternatively, a ~0.52 wt% CNF solution was prepared by following the above method but using 26 mL CNF gel in 29 mL water and with 0.42 g pullulan. Once dried, the CNF content of this solution was ~40 wt%.

[0196]

[0185] Table 1 summarises these formulations. Weights used are for making one A4 cellophane sheet. One “dot” uses 0.25 to 2 mL of Composition A solution per seed.

[0197]

[0198]

[0186] With active agent: One or more active agent(s), such as a fungicide, KARi, microbe, etc. was added with stirring to the aqueous CNF / polysaccharide precursor composition without active above, cooled first if necessary.

[0199] 1.2.1 - Rhizobia active

[0200]

[0187] A PGPR rhizobia culture was used (Bradyrhizobium diazoefficiens strain USDA110 and its generated compatible soybean rhizobia containing DsRed reporter (Xitong, 2021) cultured in yeast mannitol broth (YMB; Vincent, 1970) at 28 °C for 3 d and diluted to OD 600 = 0.1 before inoculation) containing 1 x 108colony forming units (CFU) mL'1. A total dose of 1.5 x 108CFU / seed was desired, assuming an 80% survival rate (i.e., equivalent to an active microbe dose of 1.2 x 108CFU / seed). Each seed required 0.0286 mL of the PGPR culture. A 2 mL precursor composition dot size per seed was used. DsRed PGPR was used as a fluorescent reporter to ensure the correct PGPR had been delivered.

[0201]

[0188] Table 2 shows the compositions containing rhizobia culture:

[0202]

[0203]

[0189] Under the same conditions, using traditional PGPR solutions with the same concentration and an 80% delivery efficiency, would require c. 0.02 mL PGPR solution per seed - one order of magnitude more. Therefore, the swellable composite herein demonstrates significant advantages in the efficiency and cost-effectiveness of PGPR delivery compared to traditional methods.

[0204] 1.2.2 - PGR active

[0205]

[0190] A KARi concentration of 0.1 - 5000 ng per seed was used. Table 3 shows the compositions containing KARi whereby 200 ng KARi was used in 1 mL sized Composition A dots:

[0206]

[0207] 1.2.3- Fungicidal active

[0191] Table 4 shows the compositions containing EverGol® at 30% of the cotton dose as used for Australian native seeds that are contaminated into 0.5 mL Composition A “dots”:

[0208]

[0209]

[0192] Table 5 shows the compositions containing Vibrance CST®, assuming 100% cotton dose into 1 mL “dots”.

[0210]

[0211]

[0193] Table 6 shows the compositions containing Bion®, assuming 100% cotton dose into 1 mL “dots”.

[0212]

[0213] 1.2.4 - Peptide active

[0214]

[0194] Table 7 shows the compositions containing kB1 / RHPP. Peptide quantities shown assume 5 pg total peptide per 1 mL “dot” using Composition A:

[0215]

[0216]

[0217] 1.3- Preparation of nanocomposite cello phane / dots

[0218] 1.3.1 - Cellophane

[0219]

[0195] The precursor compositions obtained in Section 1.2 above were poured into a tray and distributed evenly across its surface and allowed to dry. Once dried, the cellophane was removed from the tray and stored in a sealed container.

[0220] 1.3.2 -Dots

[0221]

[0196] For dots, the solutions obtained in Section 1.2 above were pipetted in very small drops (0.25 mL to be delivered as a prill) for very small seeds (e.g. Leptospermum erubescens), small drops (0.5 mL) for small seeds (e.g. native bush tomato), 0.75-1.0 mL drops for medium seeds (e.g. wheat, cotton, diameter c. 15 mm), or 2.0 mL drops for large seeds (e.g. soybean) onto a tray and the dots were allowed to dry. Slow drying (ambient condition) without air flow assistance was found to produce effective swellable composite dots, but laminar air flow was able to be used to accelerate drying. Dots were removed and stored as per the cellophane sheet. Best results were obtained when the dotes were dried on a non-stick surface, but glass and silicon moulds were also acceptable surfaces for producing dots.

[0222]

[0197] Scanning electron microscopy of the dry swellable composite shows the material's compact and solid structure in a dry state. The top surface revealed agglomeration of CNFs into long ropey structures (Fig. 3) which are formed from strong secondary inter-fibril interactions, such as hydrogen bonding, which increase upon drying. A side view of the swellable composite revealed its thickness of c. 30 pm and a dense and compact form (Fig. 3).

[0223]

[0198] This dry capsule or film material was observed to turn into a gelatinous hydrogel-layer on rehydration or swelling with water, which mimics seed coat gelation or “mucilage” formation in nature which is especially common in extreme and disturbed environments to prevent seeds from drying out, promote seedling establishment, initiate DNA repair and to assist root lubrication. The swellability of the present swellable composites in certain embodiments is >16,000%, with maximum swelling reached in <30 s to 15 min (see Figure 14), but can be as high as >25,000% after a period of 2-3 hours.

[0224]

[0199] By comparison, a material comprising 1% pullulan without CNFs reached a maximum swellability of about 1,100% after 1 min, reducing to 500% at 3 min. A composite comprising non-DES treated CNFs and pullulan had a swellability of about 240% after 2 min, and a maximum swellability of about 1,400% after 40 mins. A composite comprising DES treated CNF gel without pullulan had a swellability of about 20,000% after 5 mins, and a maximum swellability of about 60,000% after 3 h.

[0225] 1.3.3 - Capsule

[0200] Capsules (see Figure 2 (a, b)) were manually manufactured in silicone wells and dried in an oven at 30-50°C. For small seeds <0.15 mL of solution was used for each side of the capsule. Capsule manufacturing equipment may alternatively be used.

[0226] 1.3.4 - Prills

[0227]

[0201] Prills utilise a dot sown below, beside or above the seed. Machinery to deliver prills in nursery settings (e.g., Pohlmans) and in-field (e.g., cotton sector) is known in the art.

[0228] 1.4 - Seed contacting

[0229]

[0202] Dried cellophane or dots were wrapped around seeds dried at preferably 15 °C and 15% RH. For wheat seeds, a dot was folded in half, the seed was placed in the middle of the folded dot and the edges were folded on each end of the seed.

[0230]

[0203] Alternatively, heat sealing was used to heat seal two opposing layers of dots or cellophane together, e.g., at the edges around seeds. Dried cellophane having <40 wt% CNF, such as having ~25 wt% CNF, were heat sealable without burning (see Figure 2(c)).

[0231]

[0204] Alternatively water was used to wet seal two opposing layers of dots or cellophane together, e.g., at the edges around seeds (see Figure 2(d)). All cellophanes were suitable for water sealing.

[0232]

[0205] Alternatively, seeds can be sealed in dry capsules (see Figure 2(a, b)).

[0233]

[0206] Alternatively, seeds were co-planted with a prill, such as placed or planted above or below or beside the prill in the planting medium.

[0234] 2 - Application to plants and results

[0235] 2.1 - No active

[0236]

[0207] The precursor composition of Section 1.2 was tested as a wet phase treatment vs. the dried swellable composite packaging of Section 1.3 by immersing seeds (i.e. , priming them) in the precursor composition and sowing the seeds moist (wet priming), or by priming in the precursor composition and drying the coated seeds for 7 days prior to planting (wet / dry priming). In all trials of cotton, native seeds and wheat, the dried swellable composite being wrapped around dried seeds drastically outperformed wet priming in terms of root growth (0.03 cm3root volume for wet priming vs. 0.15 cm3root volume for dried swellable composite) and leaf number (9 leaves at harvest for wet priming vs.

[0237] 10-12 leaves for dried swellable composite), and also outperformed the untreated control seeds (0.13 cm3root volume for untreated control vs. 0.15 cm3root volume for dried swellable composite, 7.5 leaves at harvest for wet priming vs. 10-12 leaves for dried swellable composite).

[0238]

[0208] In some cases, wet-dry priming was equally effective as the dried swellable composite in terms of seedling survival and germination efficiency (see Figure 10). This is particularly the case where seeds were fresh, and therefore less susceptible to initiation of fungal infection and seed death through the priming process wet step.

[0239]

[0209] This demonstrates that the precursor compositions described herein have utility as wet priming coatings, or as wet-dry priming compositions, for seeds in good condition in providing growth benefits. In all cases, the dried swellable composites provided benefits across all seed types and seed conditions tested.

[0240] 2.1 - Rhizobia active

[0210] A dry swellable composite (Composite A (PGPR)) with and without encapsulated DsRed Rhizobia spp. PGPR, was visualised using stereo microscopy (Figure 4), showing a clear area of red fluorescence for dots with the Rhizobia spp. PGPR that was not present in the control (Figure 4(c)). Swellable composites were then dissolved in water and those with Rhizobia spp. maintained red fluorescence for three days. Subsequent widefield microscopy captured the fluorescence from DsRed Rhizobia spp. colonies entrapped within the wet swellable composites (Figure 4(d)), revealing bright-red rod-shaped bacilli (Figure 4(e)). The swellable composite gelates on initiation of watering to release Rhizobia spp. PGPR to the plant, with nodulation and N2 fixation occurring within c. 3 weeks post wetting.

[0241]

[0211] This dry swellable composite effectively introduced Rhizobia spp. PGPR to soybean plants, as was evident in the nodulation of Rhizobia spp. PGPR-treated plants (Figure 4 (f),(g)), despite nodulation occurring at 4 weeks after seed wrapping with the dried swellable composite. Specifically, the hydrogen composite containing DsRed Rhizobia spp. PGPR resulted in c. 85 nodules per plant across two repeat trials vs. no nodules from untreated plants (absolute control) and from seeds wrapped with a swellable composite without Rhizobia spp. PGPR (control without active agent). Fluorescence electron microscopy and confocal microscopy provide clear evidence of successful DsRed Rhizobia spp. PGPR delivery to the soybean plant via the swellable composite. Specifically, the nodule is seen to fluoresce red from the outside (Figure 4(h)) and internally (Figure 4(i)), which confirms nodulation via DsRed Rhizobia spp. PGPR.

[0242]

[0212] Beyond nodule formation, plants treated with DsRed Rhizobia spp. PGPR via the swellable composite wrapped around the seeds had higher chlorophyll content and greater plant size (Figure 5) than for plants treated with swellable composites without Rhizobia spp. PGPR. Chlorophyll content in plant leaves is closely related to the nutrient condition of the plant. Across both timepoints, almost twice as much Chlorophyll a was produced in leaves of DsRed Rhizobia spp. PGPR-swellable-composite-wrapped seeds (Figure 5(a), DsRN, 0.33 mg.g'1of fresh leaf weight) as from control plants without PGPR (Un, untreated; EN, control swellable composite without PGPR active, c. 0.18 mg.g-1) and almost three times as much Chlorophyll b was produced in leaves of DsRed Rhizobia spp. PGPR-swellable-composite-wrapped seeds (0.34 mg.g-1) as from plants without PGPR (c. 0.13 mg.g-1). Similarly, the SPAD (in-field chlorophyll meter) value for PGPR-swellable-composite- wrapped seeds was almost three times greater (Figure 5(b), SPAD value, c. 40) than for control plants without PGPR (c. 14.3). Rhizobia spp. PGPR-treated plants were also 50% taller (Figure 5(c), c. 350 mm tall) than those without PGPR (c. 230 mm) and their leaves were visually greener than control plants (Figure 5(d), (e)).

[0243]

[0213] Roots also proliferated in plants that were treated with Rhizobia spp. PGPR-swellable composites relative to treatments without PGPR. The untreated plants performed consistently most poorly, even more so than the control swellable composites containing no active agent. Specifically, root surface area was 35% greater for Rhizobia spp. PGPR-swellable composite-treated plants (Figure 5(g), c. 614 cm2) than for untreated plants (454 cm2); root volume was 50% greater for Rhizobia spp. PGPR-swellable composite-treated plants (c. 11 cm3) than untreated plants (c. 7.4 cm3) and 50% moreroot tips formed on Rhizobia spp. PGPR-swellable composite-treated plants (c. 1692 root tips plant-1) than untreated plants (c. 1152 tips plant-1).

[0244]

[0214] These data indicate the successful delivery of DsRed Rhizobia spp. PGPR to soybean seeds and then seedlings via the swellable composite described herein, confirming the viability and survival of the Rhizobia spp. PGPR throughout the encapsulation process.

[0245] 2.2 - PGR active (KARi)

[0246]

[0215] Composite A (KARi) significantly improved KARi delivery to wheat plants, enhancing root tip growth at one week post-sowing compared to both an untreated control and Composite B (KARi), see Figure 6. The optimal KARi dose for wheat seeds was determined to be 200 ng per seed. The increased CNF content in Composite B hindered KARi release compared to Composite A, and burned during sealing process, unlike Composite A that did not burn.

[0247]

[0216] Composite A (KARi) was also optimised for broad native species using Solanum orbiculatum as a model (200 ng KARi / seed). Bioassay pot trials in growth cabinets demonstrated that dry swellable composites as described herein wrapped around seeds in soil delivered KARi as effectively as agar in Petri dishes, achieving 65% seedling emergence with 200 ng KARi per seed, compared to less than 5% for untreated controls. Field trials confirmed the effectiveness of dry swellable composites as described herein in improving seedling emergence (see Figure 7).

[0248]

[0217] To address fungal contamination in aging Solanum orbiculatum seeds, combinations of swellable composites according to Composition A containing active agent KARi and a fungicide (Bayer Evergol® (E), or Syngenta Vibrance® CST (V)) were tested, showing significant improvements in seedling emergence and survival rates for the KARi / fungicide combination swellable composite wrapped seeds (see Figure 8). Notably, a dose of Evergol® at 30% of the cotton dose combined with 200 ng KARi per seed resulted in up to 90% seedling survival, outperforming Vibrance® CST. Further optimisation studies indicated severe fungal contamination in Solanum orbiculatum seeds, and repeated trials confirmed that Evergol® + KARi combinations significantly enhanced seedling survival. The optimal dose of Evergol® fungicide was evaluated, revealing that Evergol® at 25-50% of the cotton dose combined with KARi was most effective, avoiding the overdosing issues observed with higher concentrations (see Figures 8 and 9).

[0249]

[0218] In Scaevola albida seeds, the optimal KARi dose determined from the agar bioassays was equivalent to 200 ng per seed. This dose resulted in 50% seed germination, compared to 0-3% for untreated seeds and 40% with the best GA3 treatment. However, when agar-primed seedlings were transferred to soil, only 14% of the KARi-treated plants survived. This low survival rate led to the incorporation of KARi into the B-Tech for further validation. Pot trials with Scaevola albida seeds demonstrated that the swellable composites described herein with 20 or 200 ng of KARi and 30% of the cotton dose of Bayer Evergol® fungicide yielded the best results, achieving 40-44% seedling survival. This was significantly higher compared to 8% survival for untreated seeds and 24% for swellable composites without KARi. Field trials further confirmed these findings, showing that the combination of 200 ng KARi with 30% cotton dose Bayer Evergol® fungicide resulted in the highest plant emergence at 67%, significantly outperforming both untreated seeds at 13% and swellable composites without KARi at 8% (see Figure 11).

[0219] In Hibbertia diffusa seeds, agar treatments with 20 ng of KARi par seed resulted in 53% germination, compared to 40% for untreated seeds. Priming seeds with 200 ng of KARi increased germination rates to 63%. When these primed seedlings were transferred to soil, their survival rate was 33%, significantly higher than the 0-4% survival rate for both untreated seeds and those treated with 20 ng of KARi. In Hibbertia diffusa pot trials, combining KARi (20 or 200 ng) with 30% cotton dose Bayer Evergol® fungicide in a swellable composite resulted in 48% seedling emergence, nearly double the 28% for untreated seeds. Field trials showed 58% plant emergence with swellable composites containing 200 ng KARi and 30% cotton dose Bayer Evergol® per seed, compared to 46% for swellable composites without KARi and 42% for untreated seeds (see Figure 12). All plants survived despite adverse weather. Hibbertia diffusa seeds also comprise a hard seed coat, and the swellable composite appears to assist germination by softening the seed coat (even without KARi), which accelerates seedling establishment.

[0250]

[0220] The delivery of KARi to Leptospermum erubescens through swellable composite prills (0.25 mL precursor composition dried swellable composite dots planted below the seeds) effectively overcome the challenges of the species' tiny, dust-like seeds. Optimal dosages equivalent to 20 ng and 200 ng per seed on agar yielded around 80% germination, outperforming untreated seeds and matching the best agar GA3 treatment. Agar priming with 200 ng KARi resulted in 61% germination but only 32% survival in soil (see Figure 13(a),(b)). In contrast, pot trials with 0.25 mL swellable composite prills containing 20 ng KARi per seed and 0.5 mL swellable composite prills with 200 ng KARi per seed significantly improved seedling establishment, with better survival rates than untreated controls (see Figure 13(c),(d)). The smaller 0.25 mL prill was as effective as the larger 0.5 mL one, suggesting efficient use of lower doses.

[0251]

[0221] PGR release (KARi, PBZ) from the swellable composites described herein into free water is shown in Figure 15.

[0252] 3 - Use of swellable composite as tissue culture medium

[0253]

[0222] Using the native species Eucalyptus melliodora, more seeds germinated on the hydrated swellable composite (Composite A) (“B-Tech”) containing KARi (placed onto agar without KARi) than seeds sown directly onto agar containing KARi (see data in Figure 20). The swellable composite could much more effectively deliver PGRs to plants in tissue culture if plants are grown directly on the swellable composite than in agar.

[0254]

[0223] The present invention is described with reference to the above examples. It is to be understood that the examples are illustrative of and not limiting to the invention described herein.

[0255]

[0224] It will be apparent to the person skilled in the art that while the invention has been described in some detail for the purposes of clarity and understanding, various modifications and alterations to the embodiments and methods described herein may be made without departing from the scope of the inventive concept disclosed in this specification.

Claims

1. Claims1. A precursor composition, comprising:dispersed cellulose nanofibres (CNFs) and / or cellulose microfibres (CMFs);a water-soluble polysaccharide;optionally, an active agent; andwater,wherein the dispersed CNFs and / or CMFs and water soluble polysaccharide are present in a mass ratio of CNFs and / or CMFs:polysaccharide of from 1:1 to 1:5.

2. The precursor composition of claim 1 , comprising an active agent.

3. A swellable composite for enhancing seed viability, seed germination, root development and / or plant growth, comprising:less than 60 wt% cellulose nanofibres (CNFs) and / or cellulose microfibres (CMFs); least 40 wt% of a water-soluble polysaccharide; andan active agent, wherein the active agent is for controlled release on swelling of the swellable composite in water.

4. The swellable composite of claim 3, wherein the swellable composite has a swellability of at least 10,000% after a period of 30 min immersion in water at 25°C5. The swellable composite of claim 3 or claim 4, in the form of a film, a prill, or a capsule, comprising less than 1 wt% water.

6. The swellable composite of any one of claims 3 to 5, that is a film-forming swellable composite.

7. The precursor composition or swellable composite of any one of the preceding claims, comprising CNFs, wherein the CNFs have a diameter of from 1 to 20 nm, a length of from 500 to 2,500 nm, and an aspect ratio of from 200 to 1 ,000, optionally wherein the CNFs are obtained from a spinifex grass within the genera Triodia, Monodia, or Symplectrodia, preferably wherein the CNFs are sourced from T. pungens, T. shinzii, T. basedowii or T. longiceps.

8. The precursor composition or swellable composite of any one of the preceding claims, wherein the water soluble polysaccharide is a non-ionic polysaccharide that has a solubility in water of at least 33 mg / L at a temperature of 25 °C.

9. The swellable composite of any one of the preceding claims, wherein the dispersed CNFs and / or CMFs and water soluble polysaccharide are present in a mass ratio of CNFs and / or CMFs:polysaccharide of from 1:1 to 1:5.

10. The precursor composition or swellable composite of any one of the preceding claims, wherein the active agent is selected from one or more of: a plant growth regulator, a peptide, a microbe, a fungicide, and a pesticide, optionally wherein the active agent comprises a plant growth regulator and / or a microbe and / or a fungicide.11.The precursor composition or swellable composite of any one of the preceding claims, wherein the active agent is a plant growth regulator, selected from the group consisting of a karrikin and a plant growth promoter such as an auxin, a gibberellin, a cytokinin, a brassinosteroid, or zeatin.

12. The precursor composition or swellable composite of any one of the preceding claims, wherein the active agent is a peptide, selected from the group consisting of a CLE peptide, a systemin, a root hair promoting peptide (RHPP) and kalata B1.

13. The precursor composition or swellable composite of any one of the preceding claims, wherein the active agent is a fungicide selected from the group consisting of: thiram, captan, carboxin, metalaxyl, fludioxonil, difenoconazole, tebuconazole, azoxystrobin, thiamethoxam, triadimenol, mancozeb, pyraclostrobin, sedaxane, and penflufen.

14. The precursor composition or swellable composite of any one of the preceding claims, wherein the active agent is a microbe or plant growth promoting microorganism (PGPM), wherein the PGPM is a plant growth promoting rhizobacteria (PGPR) or a beneficial fungus.

15. The precursor composition or swellable composite of any one of the preceding claims, wherein the active agent is a microbe is a plant growth promoting rhizobacteria (PGPR) selected from a nitrogen fixing PGPR selected from one or more of the genera Rhizobium, Sinorhizobium, Azorhizobium, Allorhizobium, Mesorhizobium, Bradyrhizobium, Burkholderia, and Herbaspirillum spp., preferably from the genera Rhizobiunr, and a non-nitrogen fixing PGPR selected from the genera Bacillus spp. and / or Pseudomonas spp, or is a beneficial fungus selected from a mycorrhizal fungus from the phyla Glomeromycota, Ascomycota or Basidiomycota, a Trichoderma spp., or Penicillium bilaiae.

16. The precursor composition or swellable composite of any one of the preceding claims, wherein:the active agent is a microbe and is present in the precursor composition in a concentration sufficient to provide from 1 x 106to 1 x 109CFU microbes per seed; orthe active agent is a plant growth regulator and is present in the precursor composition in a concentration sufficient to provide from 0.1 ng to 5000 ng of the active agent per seed; or the active agent is a peptide and is present in the precursor composition in a concentration sufficient to provide from 2 pg to 5 pg stable peptide per seed; orthe active agent is a fungicide and is present in the precursor composition in a concentration sufficient to provide from 0.2 ng to 18 ng fungicide per seed.

17. A method of enhancing seed viability, seed germination, root development and / or plant growth, comprising:wet priming a seed with a precursor composition according to any one of claims 1 to 2 or 7 to 16 and sowing the seed while the precursor composition is still wet, orwet / dry priming, that is, priming the seed with precursor composition, allowing the seed with the precursor composition coating to dry to form a dried layer of swellable composite around the seed, and subsequently planting the dried seed with the swellable composite coating.

18. A method of enhancing seed viability, seed germination, root development and / or plant growth, comprising:co-planting a seed with or within a swellable composite according to any one of claims 3 to 16, andapplying water to the swellable composition to cause it to swell.

19. The method of claim 18, wherein co-planting comprises wrapping, packaging, or encapsulating the seed within a swellable composite film or cellophane wrap, package or capsule, or comprises planting the seed adjacent to a prill of the swellable composite.

20. The method of any one of claims 17 to 19, wherein the swellable composite comprises an active agent, and wherein:the active agent is a plant growth regulator and is present in the swellable composite at a concentration of from 0.1 ng to 5000 ng of the active agent per seed, orthe active agent is a peptide and is present in the swellable composite at a concentration of from 2 g to 5 pg stable peptide per seed, orthe active agent is a fungicide and is present in the swellable composite at a concentration of from 0.2 ng to 18 ng fungicide per seed, orthe active agent is a microbe and is present in the swellable composite at a concentration of from 1 x 106to 1 x 109CFU microbes per seed.

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