Orchid seed matrix particle for direct seeding in field and preparation method of orchid seed matrix particle

Abstract

The invention belongs to the technical field of orchid seedling culture, and discloses orchid seed matrix particles for field direct seeding and a preparation method, and the matrix particles comprise coco coir powder, peat soil, a porous inorganic matrix, a degradable adhesive, a bio-organic fertilizer, symbiotic bacteria, orchid seeds and water. The matrix particles adopt a core-shell structure, the core contains seeds, symbiotic bacteria and the like for water retention and moisture retention, and the shell is a porous inorganic matrix and the like for guaranteeing ventilation and mechanical strength. The granules can be directly sown in a field, do not need laboratory seedling culture, can realize high-efficiency seed germination and in-situ mycorrhiza colonization, has the seedling rate close to that of traditional sterile seedling transplantation, reduces labor and facility investment, reduces the disease risk, and is suitable for large-scale planting of orchid plants such as bletilla striata and dendrobe.

Description

Technical Field

[0001] This invention belongs to the field of orchid seedling technology, and specifically relates to an orchid seed substrate granule for direct field seeding and its preparation method. Background Technology

[0002] Orchidaceae plants such as Bletilla striata and Dendrobium spp. are commonly used traditional Chinese medicinal herbs, their seeds being as tiny as dust. The seed structure of orchids is relatively simple, generally consisting of a seed coat and an embryo. The seed coat is very thin, the embryo is also small, and most orchid seeds lack endosperm when mature. This structure is an adaptation of orchids to their environment. Orchid seeds are numerous and can be dispersed over long distances by wind and other means. The lack of endosperm makes the seeds lighter, which facilitates dispersal.

[0003] Under natural conditions, most orchid seeds need to form a mycorrhizal symbiotic relationship with specific fungi to obtain nutrients during germination, in order to compensate for the lack of nutrition provided by the endosperm.

[0004] Currently, artificial cultivation mainly relies on tissue culture or seedling cultivation followed by transplanting. This process is cumbersome, time-consuming, and labor-intensive. Furthermore, transplanting can easily damage roots, resulting in a low survival rate, which severely restricts its standardized large-scale propagation and promotion.

[0005] Chinese invention patent (CN113475189A) discloses a seed-fungus symbiotic germination complex for orchid plants, its preparation method, and its application. The patented method involves preparing a seed-fungus mixed suspension from seeds and fungal mycelium. This suspension is then dripped into a sodium alginate aqueous solution to obtain an embedded body. After hardening, the embedded body yields the seed-fungus symbiotic germination complex. The complex is spherical, and each complex contains 5-10 seeds. After sowing, the seeds germinate and begin to form seedlings approximately 30 days later. It exhibits a high germination rate and seedling survival rate, and can be directly applied to sowing under natural conditions and large-scale centralized seedling cultivation. The method boasts advantages such as simple manufacturing process, low cost, commercial production capability, convenient storage, transportation, and use, high seed germination rate, and rapid seedling formation.

[0006] In the implementation of the above-mentioned existing technologies, the complex still needs to germinate in a culture medium. Similar to the tissue culture method, it still needs to be cultivated in the laboratory and cannot be directly sown to the field.

[0007] Based on this, we propose a seed matrix granule for orchid plants used for direct seeding in the field and its preparation method. Summary of the Invention

[0008] One object of the present invention is to provide a seed substrate granule for orchid direct seeding in the field, the substrate granule comprising coconut coir powder, peat moss, porous inorganic substrate, biodegradable binder, bio-organic fertilizer, symbiotic bacteria, orchid seeds and water.

[0009] Preferably, the matrix particles consist of 35% to 45% coconut coir powder, 20% to 30% peat moss, 8% to 15% porous inorganic matrix, 5% to 10% biodegradable binder, 2% to 6% bio-organic fertilizer, 0.5% to 2% symbiotic bacteria, 5 to 10 orchid seeds, and 15% to 25% water.

[0010] Preferably, the matrix particles have a core-shell structure, with the orchid seeds, symbiotic bacteria, coconut coir powder, and peat moss forming the core, and the porous inorganic matrix and bio-organic fertilizer forming the shell. The porosity of the outer shell is greater than that of the core.

[0011] The kernel (seed chamber) is primarily composed of coconut coir and peat moss, possessing high capillary water retention capacity. This helps maintain a stable water film layer, reducing the damage to the seed embryo caused by short-term fluctuations in moisture levels. The kernel's fine pores contribute to maintaining high relative humidity and minimizing direct airflow impact.

[0012] The outer shell (aeration shell) is made of a porous inorganic matrix (perlite / vermiculite) as its framework. The pores are interconnected and have a relatively large diameter, which facilitates oxygen diffusion, physical integration with soil particles, and mechanical strength. The ratio of the inner to outer shell and the porosity form a three-phase gradient of "water-air-nutrients", which ensures the water required for germination, meets the oxygen supply, and provides channels for roots to extend outward.

[0013] Preferably, the orchid is Bletilla striata or Dendrobium, and the symbiotic fungus is arbuscular mycorrhizal fungus (AMF). Loading symbiotic fungal spores inside the granules allows the germinating roots to quickly form a symbiotic relationship with beneficial bacteria, improving nutrient absorption efficiency, enhancing root resistance, and partially replacing the mycorrhizal requirements of aseptic culture conditions. Bletilla striata and Dendrobium have a strong dependence on mycorrhizae; this invention achieves "in-situ aseptic replacement" through in-situ symbiotic fungi within the granules.

[0014] Preferably, the biodegradable binder is corn starch or seaweed gum, and its degradation rate is fast-degrading. The binder provides mechanical integrity and resistance to pressure and abrasion during granulation and sowing, facilitating transportation and mechanized sowing. After sowing, it gradually degrades under humid and hot conditions, forming pores and microchannels, allowing the radicle to break through and connect with the external soil. By selecting a binder with a fast degradation rate, the germination period and root penetration time window can be controlled.

[0015] Preferably, the bio-organic fertilizer is an organic slow-release fertilizer or microbial fertilizer, which is distributed in the core in the form of slow-release microparticles, and the slow-release time is 7 to 60 days under water immersion conditions.

[0016] Bio-organic fertilizers are dispersed in the core in slow-release formulations or granular form, creating localized high-nutrient zones. This allows the radicle and primary roots to receive a continuous and mild supply of nitrogen, phosphorus, potassium, and trace elements during the germination stage, reducing the uncertainty caused by competition from the external soil.

[0017] Preferably, the porous inorganic matrix is ​​perlite or vermiculite.

[0018] Preferably, the particle size of the matrix particles is 0.8~1.2cm, which facilitates mechanized strip sowing or spot sowing.

[0019] Another object of the present invention is to provide a method for preparing orchid seed substrate particles for direct field seeding, comprising the following steps: S1 Mix coconut coir powder, peat moss, orchid seeds and symbiotic fungal spore powder in proportion, add water and biodegradable binder, stir evenly and then granulate; S2 Slowly mix the porous inorganic matrix and bio-organic fertilizer evenly, add the remaining water and biodegradable binder, and stir evenly; S3 encapsulates the mixture obtained in S2 onto the outer layer of the particles obtained in S1, forming a core-shell structure; S4. The matrix particles obtained in S3 are dried to a moisture content of <10%.

[0020] Preferably, the granulation method is roller granulation, film pressing granulation, or hand granulation.

[0021] Preferably, the drying method is low-temperature drying or natural air drying, wherein the temperature of low-temperature drying is ≤40℃.

[0022] The present invention has the following beneficial effects: This invention relates to orchid seed matrix granules for direct field sowing, which employ a core-shell structure. The core forms a high-humidity, low-mechanical-stress "seed chamber" to maintain the continuous capillary water film and micro-oxygen balance required for seed germination. The outer shell utilizes a porous inorganic matrix network with relatively high porosity to ensure good contact with the field soil, rapid gas exchange, and mechanical strength. Coconut coir powder and peat moss together constitute a hydrophilic porous framework, providing capillary water absorption / retention. The porous inorganic material forms interconnected gas and water channels on the outer layer to ensure coupling with the soil. A biodegradable binder imparts the mechanical integrity required during granulation and sowing, and degrades at the designed rate after sowing, forming functional channels that facilitate root breakthrough and interconnection with the field soil during germination. The bio-organic fertilizer establishes a local nutrient gradient within the granules in a slow-release form, providing nutrients for the radicle and primary roots. Symbiotic fungal spores rapidly establish a symbiotic zone within the granules, reducing dependence on external sterile conditions. This enables efficient germination, in-situ mycorrhizal colonization, and natural integration of later growth with the field soil in a non-sterile, field environment. The synergistic effect of this partitioned structure and composition ensures that the granules of this invention not only guarantee seed germination and early rooting within the granules (in-situ seedling cultivation), but also allow roots to smoothly penetrate the granules after germination and quickly establish normal nutrient and water exchange with the surrounding soil, thus adapting to direct seeding environments and reducing transplant stress and disease risks.

[0023] Laboratory-based aseptic seedling cultivation requires sterile culture media, strict environmental conditions, and precise transplanting procedures. During transplanting, the root system is easily damaged, subject to soil pathogen stress, and incurs high costs. In contrast, the granules of this invention directly complete germination, mycorrhizal colonization, and early fertilization in the field, avoiding transplanting stress, reducing labor and facility inputs, and reducing disease occurrence through a locally closed microecology and beneficial bacteria. This invention not only achieves seedling survival rates and growth rates similar to traditional transplanting methods but also significantly reduces facility and cost inputs, saving over 50% of the production cost per acre for Bletilla striata or Dendrobium nobile, greatly improving the economic viability and scalability of orchid medicinal plant cultivation. Attached Figure Description

[0024] Figure 1 This is a flowchart of the matrix particle preparation method.

[0025] Figure 2 This is a photograph of the Bletilla striata seed matrix particles prepared in Example 1.

[0026] Figure 3 This is a photo of the seedling stage after field sowing of Bletilla striata seeds in Example 1.

[0027] Figure 4 This is a schematic diagram of the root penetration time series of matrix particles. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0029] Example 1: Preparation of Bletilla striata seed matrix granules S1. Core Manufacturing: First, weigh 400 g of coconut coir powder and 250 g of peat moss and mix them evenly. Then, add 10 g of Bletilla striata seeds and 20 g of symbiotic fungal spore powder, and mix them evenly using slow, low-speed stirring (≤30 rpm) to avoid damage to the dusty seeds due to shear force, while ensuring that the fungal spores are evenly distributed in the core environment of the granules. The coconut coir and peat moss form a water-retaining core framework. Next, slowly add 200 ml of deionized water and 50 g of corn starch powder as a core granulation binder. Finally, place the mixture in a drum granulator, mix evenly, and granulate. S2. Manufacturing the outer shell: Weigh 150 g of vermiculite and 30 g of bio-organic fertilizer, mix them evenly, and use this as the outer shell matrix material. The vermiculite provides air permeability and a supporting structure, while the organic fertilizer forms an initial nutrient reservoir in the matrix. Slowly add 200 ml of deionized water and 50 g of corn starch while stirring. S3, Shell Enveloping Core: The mixture obtained in S2 is wrapped around the core particles obtained in S1 to prepare particles with a diameter of 0.8–1.2 cm, ultimately forming a core-shell partitioned structure; S4. Drying and Storage: Place the formed granules in a low-temperature drying oven (≤40 ℃) to dry until the moisture content is <10% to ensure storage stability and resistance to pressure during transportation. After cooling, the obtained Bletilla striata seed matrix granules are vacuum-sealed in aluminum foil bags and stored in a cool, dark place at room temperature. The shelf life is 3–6 months. (Refer to...) Figure 1 ) The prepared Bletilla striata seed substrate granules were directly sown in the field, referring to... Figure 2 and Figure 3 .

[0030] 1. Sowing depth and covering soil Sowing depth: The soil covering the top surface of the particles is 1.0–2.0 cm thick (i.e., the particles are buried about 1–2 cm below the soil surface). Covering requirements: After fine raking, cover with loose soil. The soil compaction should be light to ensure good contact between the particles and the soil without crushing the particles.

[0031] 2. Immediate post-broadcast management (first 0–30 days, critical moisturizing period) Shading: For the first 7–14 days after sowing, use shade nets to cover 30%–50% of the surface when the sun is strong (it is recommended to cover 50% when the daytime maximum temperature is >30℃) to reduce evaporation and lower the surface temperature.

[0032] Mulching (optional): In arid or windy areas, the ground can be covered with breathable agricultural film (water-permeable non-woven fabric) to retain moisture, but ensure breathability to avoid stuffiness.

[0033] Initial irrigation: Irrigate immediately after sowing (rinsing is prohibited - fine mist or micro-spraying should be used) to moisten the soil surface and particles; thereafter keep the surface soil moist but not waterlogged.

[0034] 3. Irrigation frequency and dosage Days 0–7: Lightly spray once a day (0.5 times in the morning and 0.5 times in the evening, depending on the weather), each time watering to moisten the top 0–2 cm of soil (soil moisture content restored to 60%–80% of field capacity).

[0035] Days 8–30: Lightly spray every 2–3 days; if there is sufficient rainfall, the frequency can be reduced appropriately.

[0036] Note: Avoid using high-flow-rate flushing to prevent particle displacement or breakage.

[0037] 4. Growth maintenance (30–90 days) and topdressing management 4.1 Timing and Procedures for Growth Monitoring Day 7: Check if the granules are cracked and if there are signs of germination (radicles emerging and substrate swelling).

[0038] Day 14: Record the germination rate and seedling uniformity; observe signs of mycorrhizal colonization (a few seedlings can be randomly dug up for inspection).

[0039] Day 30: Initial assessment of seedling survival rate and recording of plant height and root length.

[0040] Days 60–90: Consider whether to supplement fertilizer or thin out / thin the seedlings based on the growth situation.

[0041] 4.2 Topdressing Recommendations Observation-based supplemental fertilization: Day 30: If the seedlings are growing slowly, apply a low concentration of water-soluble fertilizer (N:P:K ratio 10:10:10, diluted to 0.2–0.5 times the conventional concentration) between the rows, at a rate of 5–10 kg per acre (after dilution).

[0042] Day 60: Depending on the growth status, apply trace elements (such as boron and zinc) by foliar spraying. A single small-dose spray is recommended.

[0043] Reference Figure 4Schematic diagram of root penetration time series of matrix particles t0 stage (early sowing stage) The matrix particles have an intact structure, and the binder layer inside the outer shell has not degraded, maintaining the overall strength of the particles and preventing seed loss during sowing and covering. The seed is located in the kernel region, where the closed, moist environment formed by the binder and outer shell provides suitable moisture and gas exchange for seed germination.

[0044] t1 stage (seed germination period, approximately 7–15 days) Under the influence of soil moisture and microorganisms, the binder begins to partially degrade, creating micropores in the outer shell and gradually increasing aeration and porosity. The seed radicle breaks through the kernel, extending outward along the pores and binder degradation channels, gradually contacting the surrounding soil. Slow-release fertilizer begins to dissolve and release nutrients at this stage, providing initial nutrition to the young roots.

[0045] t2 stage (root growth and development period, approximately 15–30 days) The binder has largely degraded, and the particles are fully connected to the external soil, gradually integrating the core with the external soil environment. Roots penetrate the particles and extend into the surrounding soil, forming a stable root-soil-microbe coupling system. Symbiotic bacteria colonize the root system, promoting seedling nutrient absorption and stress resistance.

[0046] Example 2: Preparation method of Dendrobium seed matrix granules S1. Core Manufacturing: First, weigh 350 g of coconut coir powder and 280 g of peat moss and mix them evenly. Then, add 5 g of Dendrobium seeds and 30 g of symbiotic fungal spore powder, and mix them evenly using slow, low-speed stirring (≤30 rpm) to avoid damage to the dusty seeds due to shear force, while ensuring that the fungal spores are evenly distributed in the core environment of the granules. The coconut coir and peat moss form a water-retaining core framework. Next, slowly add 220 ml of deionized water and 50 g of corn starch powder as a core granulation binder. Finally, place the mixture in a drum granulator, mix evenly, and granulate. S2. Making the outer shell: Weigh 150 g of perlite and 40 g of bio-organic fertilizer and mix them evenly as the outer shell matrix material. Perlite provides air permeability and supporting structure, while organic fertilizer forms an initial nutrient pool in the matrix. Slowly add 200 ml of deionized water and 50 g of corn starch while stirring. S3, Shell Enveloping Core: The mixture obtained in S2 is wrapped around the core particles obtained in S1 to prepare particles with a diameter of 0.8–1.0 cm, ultimately forming a core-shell partitioned structure; S4. Drying and Storage: Place the shaped granules in a low-temperature oven (≤40 ℃) to dry until the moisture content is below 10%. After cooling, pack them into aluminum foil bags and vacuum seal them. Store them in a cool, dry environment at room temperature. They can be stably stored for 3–6 months.

[0047] The field sowing method and specifications for Example 2 are the same as those for Example 1.

[0048] Comparative test Experimental design: Treatments: A. Aseptic seedling raising in the laboratory → transplanting (Control 1); B. Direct broadcasting of naked seeds (Control 2); C. Direct sowing of the substrate granules of this invention in the field (Example 1 of this invention).

[0049] Each treatment consists of 3 replicates (plots or pots), with 100 seeds sown per replicate (total n=300). Observation time points: 14 days, 30 days, 60 days, and 90 days after emergence; mycorrhizal detection was performed at 60 days.

[0050] Statistical methods: One-way ANOVA followed by Tukey multiple comparisons; significance level p=0.05. Report as mean ± SD; indicate "significant" in the text by p-value (p<0.05, p<0.01, p<0.001).

[0051] Key performance indicator results: Indicators (time) A: Aseptic seedling raising → transplanting (Control 1) B: Direct sowing of naked seeds (Control 2) C: This invention involves live particle streaming. Germination rate in the laboratory (but not yet transplanted) (14 days) 95.0% ± 3.0% — — Field emergence rate (calculated with the sowing date as 0, 30 days) 68.0% ± 6.0% 12.0% ± 4.0% *72.0% ± 5.0% Seedling survival rate (field survival, 60 days) 63.0% ± 6.5% 8.0% ± 3.0% *62.0% ± 5.0% T50 (Number of days from sowing to 50% emergence) 45 ± 3 d 35 ± 4 d *18 ± 2 d Mycorrhizal colonization rate of roots (60 days, staining count) 30.0% ± 8.0% 5.0% ± 3.0% *78.0% ± 6.0% Plant height (cm, 60d) 12.5 ± 1.8 5.2 ± 1.4 *11.3 ± 1.6 Root length (cm, 60d) 9.0 ± 1.2 3.8 ± 0.9 *8.4 ± 1.0 Dry weight per plant (g, 60d) 0.85 ± 0.12 0.18 ± 0.05 *0.78 ± 0.10 Particle breakage rate (%) after mechanical sowing — — 6.0% ± 2.0% Seed escape / exposure rate (losses after sowing, 30 days) — 42.0% ± 5.0% *4.0% ± 1.0% Disease / seedling incidence (90 days) 12.0% ± 4.0% 25.0% ± 6.0% *8.0% ± 3.0% Note: * indicates a particularly prominent advantage of Embodiment 1 of the present invention compared to "Comparative Study 1" or "Comparative Study 2".

[0052] C vs B (Example 1 of this invention vs naked seed): C is significantly better than naked seed in core indicators such as germination rate, seedling establishment rate, mycorrhizal colonization rate, plant height, root length, dry weight, and disease incidence (p<0.001).

[0053] C vs A (Example 1 of this invention vs. aseptic seedling raising → transplanting): Emergence / Seedling survival rate: No significant difference (p>0.05); that is, the final seedling survival rate of the present invention in the field can reach a level comparable to that of the transplanting method.

[0054] Growth (plant height, root length, dry weight): slightly lower than the transplanted group, but the difference was not significant.

[0055] T50 (from sowing): This invention predates the transplanting method significantly (p<0.001) because the transplanting method requires indoor seedling raising before transplanting.

[0056] Field comparative trials showed that, under the same sowing quantity (300 seeds per treatment, three replicates) and the same field management conditions, the emergence rate of the substrate granule group of this invention was 72.0% ± 5.0% 30 days after sowing, significantly higher than that of the naked direct seeding group (12.0% ± 4.0%, p<0.001), and there was no significant difference in field survival rate compared with the traditional indoor seedling-transplanting group (68.0% ± 6.0%) (p>0.05). At 60 days, the mycorrhizal colonization rate of the group of this invention was 78.0% ± 6.0%, much higher than that of the naked seeding group (5.0% ± 3.0%), further demonstrating that the symbiotic fungal load of this invention significantly shortened the mycorrhizal establishment period and improved early nutrient absorption. Comprehensive growth indicators (plant height, root length, dry weight) also showed that this invention can achieve growth levels close to or equivalent to those of the transplanting method under direct seeding conditions in the field, while significantly reducing seed loss and disease incidence during sowing.

[0057] Conclusion: Under the premise of "reducing labor and facility input," cost calculations show that the substrate granule direct seeding method of this invention is superior to the traditional seedling transplanting method in terms of seed utilization, facility input, and labor costs. Under the same cultivation scale, it can save 4,000–6,000 yuan per mu in comprehensive costs, reducing production costs by more than 50% compared to aseptic seedling transplanting and reducing seed and labor waste by about 70% compared to naked seeding, significantly improving cultivation economics. This invention can achieve similar seedling survival rate and growth as the traditional seedling transplanting method in field direct seeding, while significantly outperforming naked seeding.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A seed substrate granule for orchid plants used in direct field seeding, characterized in that, The matrix particles consist of coconut coir powder, peat moss, porous inorganic matrix, biodegradable binder, bio-organic fertilizer, symbiotic bacteria, orchid seeds, and water.

2. The matrix particles as described in claim 1, characterized in that, The matrix particles consist of 35%–45% coconut coir powder, 20%–30% peat moss, 8%–15% porous inorganic matrix, 5%–10% biodegradable binder, 2%–6% bio-organic fertilizer, 0.5%–2% symbiotic bacteria, 5–10 orchid seeds, and 15%–25% water.

3. The matrix particles as described in claim 1, characterized in that, The matrix particles adopt a core-shell structure, with the orchid seeds, symbiotic bacteria, coconut coir powder and peat moss forming the core, and the porous inorganic matrix and bio-organic fertilizer forming the shell.

4. The matrix particles as described in claim 1, characterized in that, The orchid seeds are Bletilla striata seeds or Dendrobium seeds, and the symbiotic fungus is arbuscular mycorrhizal fungus (AMF).

5. The matrix particles as described in claim 1, characterized in that, The biodegradable binder is corn starch or seaweed gum.

6. The matrix particles as described in claim 1, characterized in that, The bio-organic fertilizer is either organic slow-release fertilizer or microbial fertilizer.

7. The matrix particles as described in claim 1, characterized in that, The porous inorganic matrix is ​​perlite or vermiculite.

8. The matrix particles as described in claim 1, characterized in that, The particle size of the matrix particles is 0.8~1.2cm.

9. A method for preparing orchid seed substrate particles for direct field seeding, comprising preparing substrate particles as described in any one of claims 1-8, characterized in that, Includes the following steps: S1 Mix coconut coir powder, peat moss, orchid seeds and symbiotic fungal spore powder in proportion, add water and biodegradable binder, stir evenly and then granulate; S2 Slowly mix the porous inorganic matrix and bio-organic fertilizer evenly, add the remaining water and biodegradable binder, and stir evenly; S3 encapsulates the mixture obtained in S2 onto the outer layer of the particles obtained in S1, forming a core-shell structure; S4. The matrix particles obtained in S3 are dried to a moisture content of <10%.

10. The preparation method according to claim 9, characterized in that, The drying method is low-temperature drying or natural air drying.

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