Zn-si composite foliar fertilizer-based rice zinc nutrition strengthening method and application thereof

Abstract

This invention relates to the field of crop nutrient regulation technology, and particularly to a method for fortifying rice with zinc based on Zn-Si compound foliar fertilizer and its application. The method includes: during rice cultivation, foliar fertilizers I-III are sprayed onto rice leaves at the early booting stage, the rapid elongation stage of young panicles, and the stage from pollen mother cell meiosis to microspore formation, respectively; foliar fertilizers I-III all contain nano-zinc oxide and monosilicic acid; the particle sizes of the nano-zinc oxide in foliar fertilizers I-III are 45-55 nm, 30-40 nm, and 15-25 nm, respectively; the rice variety is Nanjing 46. The zinc fortification method for rice of the present invention is designed specifically for the characteristics of Nanjing 46 rice. It can overcome the zinc absorption and transport barriers and the zinc enrichment bottleneck in grains caused by the apparent silencing of OsZIP family transport proteins and the thick cuticle of leaves in Nanjing 46 rice, and activate its zinc allocation potential during the reproductive period, thereby effectively improving the zinc content, yield, number of tillers, number of grains per panicle or seed setting rate of Nanjing 46 rice.

Description

Technical Field

[0001] This invention relates to the field of crop nutrient regulation technology, and in particular to a method for fortifying rice zinc nutrition based on Zn-Si compound foliar fertilizer and its application. Background Technology

[0002] Rice is the staple food for nearly half of the world's population, and its high yield and quality are directly related to food security and residents' nutritional health. "Nanjing 46" is a high-quality soft-grain japonica rice variety bred by the Jiangsu Academy of Agricultural Sciences. Due to its soft and glutinous texture and excellent taste, it is widely planted in the middle and lower reaches of the Yangtze River. In particular, it has advantages such as low planting cost and simple management under the direct seeding cultivation mode, and the market demand is strong.

[0003] However, the "Nanjing 46" rice variety faces two major problems under the direct-seeding model: First, its yield potential has not been fully realized, as yield components such as tillering rate and grain filling rate are easily affected by environmental and nutrient supply factors; second, the zinc content in the grains is low, typically only 50-55 mg / kg under natural conditions, far below the recommended daily intake of zinc for adults (10-15 mg daily), failing to meet residents' needs for zinc supplementation through staple foods. Zinc, as an essential trace element for the human body, participates in the synthesis and metabolism of various enzymes and plays an important role in immune function regulation and growth and development. Zinc biofortification of rice has become a key research focus in the global agricultural field.

[0004] Nano-zinc oxide (ZnO NPs), as a novel zinc source, is easily absorbed by plants and has high translocation efficiency, and has been proven to be a potential material for crop nutrient fortification. For example, patent CN121517251A increased the zinc content in brown rice and simultaneously increased rice yield and reduced cadmium content by spraying a foliar fertilizer containing porous chitosan, L-malic acid, and nano-zinc oxide during the booting and grain-filling stages of rice. However, different rice varieties show significant differences in tolerance and absorption efficiency of nano-zinc oxide, and existing foliar fertilizer and spraying methods for nano-zinc oxide are not suitable for Nanjing 46. Summary of the Invention

[0005] To address the aforementioned technical problem—that existing rice nano-zinc oxide foliar fertilizers and spraying methods are not suitable for Nanjing 46 rice—this invention provides a method for fortifying rice zinc nutrition based on Zn-Si compound foliar fertilizer and its application. This method is designed specifically for the characteristics of Nanjing 46 rice, effectively improving its grain zinc content, yield, tiller number, grains per panicle, and seed setting rate.

[0006] The specific technical solution of this invention is as follows: In a first aspect, the present invention provides a method for fortifying zinc nutrition in rice based on Zn-Si compound foliar fertilizer, comprising: during rice cultivation, foliar fertilizers I to III are sprayed onto rice leaves at the early booting stage, the rapid elongation stage of young panicles, and the stage from pollen mother cell meiosis to microspore formation, respectively; foliar fertilizers I to III all contain nano-zinc oxide and monosilicic acid (Si(OH)4); the particle sizes of nano-zinc oxide in foliar fertilizers I to III are 45-55 nm, 30-40 nm, and 15-25 nm, respectively; the rice variety is Nanjing 46.

[0007] This invention targets the characteristics of the Nanjing 46 rice variety, employing a nano-zinc oxide and monosilicic acid composite system. Different particle sizes of nano-zinc oxide are used at different stages to overcome the zinc absorption and transport barriers and grain zinc enrichment bottlenecks caused by the apparent silencing of OsZIP family transport proteins and the thick leaf cuticle in Nanjing 46. It also activates its reproductive period zinc allocation potential, thereby effectively improving the grain zinc content, yield, tiller number, grains per panicle, and seed setting rate of Nanjing 46. The specific mechanism is as follows: (1) First application: At the early stage of panicle initiation, nano-zinc oxide with a particle size of 45-55 nm is applied. It mainly penetrates slowly through the cuticle. The larger particle size is conducive to the retention of nano-zinc oxide in the leaf cuticle, which can form a slow-release zinc pool in the relatively thick sword leaf epidermis of Nanjing 46. At the same time, the coexisting monosilicic acid induces the deposition of amorphous SiO2 in the epidermal cells, enhances the adhesion of nanoparticles, and slightly reshapes the microstructure of the cuticle, reserving channels for the subsequent penetration of small-diameter particles. At this stage, zinc is mainly used to maintain the activity of antioxidant enzymes such as SOD and ensure the normal differentiation of panicle primordia.

[0008] (2) Second spraying: Nano-zinc oxide with a particle size of 30~40nm can efficiently enter the symptom pathway, be recognized by OsYSL2 and loaded into the sieve tubes. At this stage, monosilicic acid can indirectly relieve the methylation inhibition of the OsZIP3 promoter region (a unique epigenetic defect of Nanjing 46) by upregulating the bZIP23 transcription factor, and significantly improve the translocation efficiency of zinc to the ear axis.

[0009] (3) Third spraying: Nano zinc oxide with a particle size of 15~25nm can be endophyted into the flower organs through stomata, releasing Zn 2+ Activation of the zinc finger protein OsDof12 promotes the expression of starch synthesis genes (OsAGPL2, OsSSIIIa), increasing thousand-grain weight. Simultaneously, Nanjing 46 is sensitive to oxidation during its reproductive period; monosilicic acid protects meiosis and reduces pollen abortion rate by scavenging excess H2O2 induced by ZnO NPs. More importantly, silicon signaling can activate OsLsi6, a transcription factor that shares the DRE element with the OsZIP11 promoter, thereby transiently upregulating OsZIP11 in the early grain-filling stage, achieving efficient loading of zinc into the endosperm.

[0010] As an optional implementation method, the rice is cultivated by direct seeding.

[0011] As an optional implementation, in foliar fertilizer I, the content of nano-zinc oxide is 70-90 mg / L (including 70 mg / L and 90 mg / L) calculated as Zn, and the content of monosilicic acid is 50-80 mg / L calculated as SiO2; in foliar fertilizer II, the content of nano-zinc oxide is 90-110 mg / L (excluding 90 mg / L, including 110 mg / L) calculated as Zn, and the content of monosilicic acid is 50-80 mg / L calculated as SiO2; in foliar fertilizer III, the content of nano-zinc oxide is 110-130 mg / L (excluding 110 mg / L, including 130 mg / L) calculated as Zn, and the content of monosilicic acid is 50-80 mg / L calculated as SiO2.

[0012] Using foliar fertilizer with progressively increasing nano zinc oxide content during three applications, combined with a design that decreases nano zinc oxide particle size, can better build a slow-release zinc pool in the leaves during the early stage of panicle development, drive directional transport of vascular bundles during the rapid elongation period of young panicles, and target and enrich reproductive organs during the period from pollen mother cell meiosis to microspore formation.

[0013] As an optional implementation, foliar fertilizers I to III also contain surfactants at a content of 0.01 to 0.05% v / v; the surfactants include Tween-20 and / or Silwet L-77.

[0014] As an optional implementation method, the solvent in foliar fertilizers I to III is water.

[0015] As an optional implementation, the preparation steps of the foliar fertilizers I to III include: dispersing nano zinc oxide in water to obtain a nano zinc oxide dispersion; adding hydrochloric acid solution to a potassium silicate solution until the pH is 6.2 to 6.8, and after complete hydrolysis, obtaining a monosilicic acid mother liquor; and mixing the nano zinc oxide dispersion with the monosilicic acid mother liquor.

[0016] As an optional implementation, in the preparation steps of foliar fertilizers I to III, a surfactant is added to the nano zinc oxide dispersion.

[0017] As an optional implementation, in the preparation steps of foliar fertilizers I to III, the method of complete hydrolysis is to let it stand for 10 to 15 minutes.

[0018] As an optional implementation, the initial stage of spikelet development is when the spikelet length reaches 1-2 cm or 7-10 days after the main stem joints; the rapid elongation period of the spikelet is when the spikelet length reaches 3-5 cm; and the period from pollen mother cell meiosis to microspore formation is 5-7 days before heading.

[0019] As an optional implementation method, the application of foliar fertilizers I through III is carried out on a sunny evening, with a spray volume of 10-30 L / 667m³. 2 (Based on soil area).

[0020] Secondly, the present invention provides the application of the zinc nutrient fortification method for rice in the cultivation of Nanjing 46 rice.

[0021] As an optional implementation method, the zinc fortification method for rice is used to improve the zinc content, yield, number of tillers, number of grains per panicle, or seed setting rate of Nanjing 46 rice.

[0022] Compared with the prior art, the present invention has the following advantages: This invention utilizes nano-zinc oxide of different particle sizes at specific stages (early panicle incubation, rapid spikelet elongation, and pollen mother cell meiosis to microspore formation) and combines it with monosilicic acid during each application to construct a composite nutrient system with spatiotemporal responsiveness and physiological synergy. This system can overcome the zinc absorption and translocation barriers and grain zinc enrichment bottlenecks caused by the apparent silencing of OsZIP family transport proteins and the thick cuticle of leaves in Nanjing 46, and activate its zinc allocation potential during the reproductive period. As a result, it can effectively improve the grain zinc content, yield, number of tillers, number of grains per spike, or seed setting rate of Nanjing 46. Detailed Implementation

[0023] The present invention will be further described below with reference to embodiments.

[0024] First, the present invention relates to a method for fortifying zinc nutrition in rice based on Zn-Si compound foliar fertilizer, comprising: during rice cultivation, foliar fertilizers I to III are sprayed onto rice leaves at the early booting stage, the rapid elongation stage of young panicles, and the stage from pollen mother cell meiosis to microspore formation, respectively; foliar fertilizers I to III all contain nano-zinc oxide and monosilicic acid; the particle sizes of nano-zinc oxide in foliar fertilizers I to III are 45-55 nm, 30-40 nm, and 15-25 nm, respectively; the rice variety is Nanjing 46.

[0025] In some specific embodiments, the rice is cultivated by direct seeding.

[0026] In some specific embodiments, the initial stage of spikelet development is when the length of the young spikelet reaches 1-2 cm or 7-10 days after the main stem elongates.

[0027] In some specific embodiments, the rapid elongation period of the young spikelet is when the length of the young spikelet reaches 3-5 cm.

[0028] In some specific embodiments, the pollen mother cell meiosis to microspore formation period is 5-7 days before heading.

[0029] In some specific embodiments, the foliar fertilizer I contains 70-90 mg / L of nano zinc oxide (calculated as Zn) and 50-80 mg / L of monosilicic acid (calculated as SiO2).

[0030] In some specific embodiments, the foliar fertilizer II contains 90-110 mg / L of nano zinc oxide (calculated as Zn) and 50-80 mg / L of monosilicic acid (calculated as SiO2).

[0031] In some specific embodiments, the foliar fertilizer III contains 110-130 mg / L of nano zinc oxide (calculated as Zn) and 50-80 mg / L of monosilicic acid (calculated as SiO2).

[0032] In some specific embodiments, foliar fertilizers I to III also contain surfactants at a content of 0.01 to 0.05% v / v; the surfactants include Tween-20 and / or Silwet L-77.

[0033] In some specific implementations, the solvent in foliar fertilizers I to III is water.

[0034] In some specific embodiments, the preparation steps of the foliar fertilizers I-III include: dispersing nano-zinc oxide in water to obtain a nano-zinc oxide dispersion; adding hydrochloric acid solution to a potassium silicate solution until the pH is 6.2-6.8, and after complete hydrolysis, obtaining a monosilicic acid mother liquor; and mixing the nano-zinc oxide dispersion with the monosilicic acid mother liquor. Optionally or preferably, a surfactant is added to the nano-zinc oxide dispersion; the complete hydrolysis is performed by standing for 10-15 minutes.

[0035] In some specific implementations, the application of foliar fertilizers I through III is carried out on a sunny evening, with a spray volume of 10-30 L / 667 m³. 2 (Based on soil area).

[0036] Secondly, the present invention provides the application of the zinc nutrient fortification method for rice in the cultivation of Nanjing 46 rice.

[0037] In some specific embodiments, the rice zinc fortification method is used to increase the zinc content, yield, number of tillers, number of grains per panicle, or seed setting rate of Nanjing 46 rice.

[0038] The present invention will now be described with reference to specific embodiments and comparative examples. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0039] Preparation Example 1: Preparation of Foliar Fertilizers I-III In this preparation example, the formulation of foliar fertilizer I is as follows: 80 mg / L of nano zinc oxide (particle size 45~55 nm) (calculated as Zn), 65 mg / L of monosilicic acid (calculated as SiO2), 0.01% v / v of Tween-80, and deionized water as the solvent. Foliar fertilizer I is prepared according to the following steps: S1: Take 2.4 g (calculated as Zn) of nano zinc oxide with a particle size of 45~55 nm, add 3 L of 35℃ deionized water, then add 3 mL of Tween-80, and sonicate for 30 min to obtain nano zinc oxide dispersion.

[0040] S2: Take 97.5 mL of potassium silicate solution with a concentration of 20 g / L (calculated as SiO2), adjust the pH to 6.5 with 0.1 mol / L hydrochloric acid solution, and let it stand for 10 min to obtain monosilicic acid mother liquor.

[0041] S3: Mix the nano zinc oxide dispersion with the monosilicic acid mother liquor and bring the volume to 30 L to obtain foliar fertilizer I.

[0042] In this preparation example, the formulation of foliar fertilizer II is as follows: 100 mg / L nano zinc oxide (particle size 30-40 nm) (calculated as Zn), 65 mg / L monosilicic acid (calculated as SiO2), Tween-80 0.01% v / v, and deionized water as the solvent. Foliar fertilizer II is prepared according to the following steps: S1: Take 3.0 g (calculated as Zn) of nano zinc oxide with a particle size of 30~40 nm, add 3 L of 35℃ deionized water, then add 3 mL of Tween-80, and sonicate for 30 min to obtain nano zinc oxide dispersion.

[0043] S2: Take 97.5 mL of potassium silicate solution with a concentration of 20 g / L (calculated as SiO2), adjust the pH to 6.5 with 0.1 mol / L hydrochloric acid solution, and let it stand for 10 min to obtain monosilicic acid mother liquor.

[0044] S3: Mix the nano zinc oxide dispersion with the monosilicic acid mother liquor and bring the volume to 30 L to obtain foliar fertilizer II.

[0045] In this preparation example, the formulation of foliar fertilizer III is as follows: 120 mg / L of nano zinc oxide (particle size 15~25 nm) (calculated as Zn), 65 mg / L of monosilicic acid (calculated as SiO2), 0.01% v / v of Tween-80, and deionized water as the solvent. Foliar fertilizer III is prepared according to the following steps: S1: Take 3.6 g (calculated as Zn) of nano zinc oxide with a particle size of 15~25 nm, add 3 L of 35℃ deionized water, then add 3 mL of Tween-80, and sonicate for 30 min to obtain nano zinc oxide dispersion.

[0046] S2: Take 97.5 mL of potassium silicate solution with a concentration of 20 g / L (calculated as SiO2), adjust the pH to 6.5 with 0.1 mol / L hydrochloric acid solution, and let it stand for 10 min to obtain monosilicic acid mother liquor.

[0047] S3: Mix the nano zinc oxide dispersion with the monosilicic acid mother liquor and bring the volume to 30 L to obtain foliar fertilizer III.

[0048] Preparation Example 2: Preparation of Foliar Fertilizers I-III In this preparation example, the formulations of foliar fertilizers I through III are as follows: 100 mg / L nano zinc oxide (particle size 30-40 nm) (calculated as Zn), 65 mg / L monosilicic acid (calculated as SiO2), Tween-80 0.01% v / v, and deionized water as the solvent. Foliar fertilizers I through III are prepared according to the following steps: S1: Take 3.0 g (calculated as Zn) of nano zinc oxide with a particle size of 30~40 nm, add 3 L of 35℃ deionized water, then add 3 mL of Tween-80, and sonicate for 30 min to obtain nano zinc oxide dispersion.

[0049] S2: Take 97.5 mL of potassium silicate solution with a concentration of 20 g / L (calculated as SiO2), adjust the pH to 6.5 with 0.1 mol / L hydrochloric acid solution, and let it stand for 10 min to obtain monosilicic acid mother liquor.

[0050] S3: Mix the nano zinc oxide dispersion with the monosilicic acid mother liquor and bring the volume to 30 L to obtain foliar fertilizers I~III.

[0051] Preparation Example 3: Preparation of Foliar Fertilizers I-III In this preparation example, the formulation of foliar fertilizer I is as follows: 80 mg / L of nano zinc oxide (particle size 30-40 nm) (calculated as Zn), 65 mg / L of monosilicic acid (calculated as SiO2), Tween-80 0.01% v / v, and deionized water as the solvent. Foliar fertilizer I is prepared according to the following steps: S1: Take 2.4 g (calculated as Zn) of nano zinc oxide with a particle size of 30~40 nm, add 3 L of 35℃ deionized water, then add 3 mL of Tween-80, and sonicate for 30 min to obtain nano zinc oxide dispersion.

[0052] S2: Take 97.5 mL of potassium silicate solution with a concentration of 20 g / L (calculated as SiO2), adjust the pH to 6.5 with 0.1 mol / L hydrochloric acid solution, and let it stand for 10 min to obtain monosilicic acid mother liquor.

[0053] S3: Mix the nano zinc oxide dispersion with the monosilicic acid mother liquor and bring the volume to 30 L to obtain foliar fertilizer I.

[0054] In this preparation example, the formulation of foliar fertilizer II is as follows: 100 mg / L nano zinc oxide (particle size 30-40 nm) (calculated as Zn), 65 mg / L monosilicic acid (calculated as SiO2), Tween-80 0.01% v / v, and deionized water as the solvent. Foliar fertilizer II is prepared according to the following steps: S1: Take 3.0 g (calculated as Zn) of nano zinc oxide with a particle size of 30~40 nm, add 3 L of 35℃ deionized water, then add 3 mL of Tween-80, and sonicate for 30 min to obtain nano zinc oxide dispersion.

[0055] S2: Take 97.5 mL of potassium silicate solution with a concentration of 20 g / L (calculated as SiO2), adjust the pH to 6.5 with 0.1 mol / L hydrochloric acid solution, and let it stand for 10 min to obtain monosilicic acid mother liquor.

[0056] S3: Mix the nano zinc oxide dispersion with the monosilicic acid mother liquor and bring the volume to 30 L to obtain foliar fertilizer II.

[0057] In this preparation example, the formulation of foliar fertilizer III is as follows: 120 mg / L of nano zinc oxide (particle size 30-40 nm) (calculated as Zn), 65 mg / L of monosilicic acid (calculated as SiO2), 0.01% v / v of Tween-80, and deionized water as the solvent. Foliar fertilizer III was prepared according to the following steps: S1: Take 3.6 g (calculated as Zn) of nano zinc oxide with a particle size of 30~40 nm, add 3 L of 35℃ deionized water, then add 3 mL of Tween-80, and sonicate for 30 min to obtain nano zinc oxide dispersion.

[0058] S2: Take 97.5 mL of potassium silicate solution with a concentration of 20 g / L (calculated as SiO2), adjust the pH to 6.5 with 0.1 mol / L hydrochloric acid solution, and let it stand for 10 min to obtain monosilicic acid mother liquor.

[0059] S3: Mix the nano zinc oxide dispersion with the monosilicic acid mother liquor and bring the volume to 30 L to obtain foliar fertilizer III.

[0060] Preparation Example 4: Preparation of Foliar Fertilizers I-III In this preparation example, the formulation of foliar fertilizer I is as follows: 100 mg / L of nano zinc oxide (particle size 45~55 nm) (calculated as Zn), 65 mg / L of monosilicic acid (calculated as SiO2), 0.01% v / v of Tween-80, and deionized water as the solvent. Foliar fertilizer I is prepared according to the following steps: S1: Take 3.0 g (calculated as Zn) of nano zinc oxide with a particle size of 45~55 nm, add 3 L of 35℃ deionized water, then add 3 mL of Tween-80, and sonicate for 30 min to obtain nano zinc oxide dispersion.

[0061] S2: Take 97.5 mL of potassium silicate solution with a concentration of 20 g / L (calculated as SiO2), adjust the pH to 6.5 with 0.1 mol / L hydrochloric acid solution, and let it stand for 10 min to obtain monosilicic acid mother liquor.

[0062] S3: Mix the nano zinc oxide dispersion with the monosilicic acid mother liquor and bring the volume to 30 L to obtain foliar fertilizer I.

[0063] In this preparation example, the formulation of foliar fertilizer II is as follows: 100 mg / L nano zinc oxide (particle size 30-40 nm) (calculated as Zn), 65 mg / L monosilicic acid (calculated as SiO2), Tween-80 0.01% v / v, and deionized water as the solvent. Foliar fertilizer II is prepared according to the following steps: S1: Take 3.0 g (calculated as Zn) of nano zinc oxide with a particle size of 30~40 nm, add 3 L of 35℃ deionized water, then add 3 mL of Tween-80, and sonicate for 30 min to obtain nano zinc oxide dispersion.

[0064] S2: Take 97.5 mL of potassium silicate solution with a concentration of 20 g / L (calculated as SiO2), adjust the pH to 6.5 with 0.1 mol / L hydrochloric acid solution, and let it stand for 10 min to obtain monosilicic acid mother liquor.

[0065] S3: Mix the nano zinc oxide dispersion with the monosilicic acid mother liquor and bring the volume to 30 L to obtain foliar fertilizer II.

[0066] In this preparation example, the formulation of foliar fertilizer III is as follows: 100 mg / L of nano zinc oxide (particle size 15~25 nm) (calculated as Zn), 65 mg / L of monosilicic acid (calculated as SiO2), 0.01% v / v of Tween-80, and deionized water as the solvent. Foliar fertilizer III is prepared according to the following steps: S1: Take 3.0 g (calculated as Zn) of nano zinc oxide with a particle size of 15~25 nm, add 3 L of 35℃ deionized water, then add 3 mL of Tween-80, and sonicate for 30 min to obtain nano zinc oxide dispersion.

[0067] S2: Take 97.5 mL of potassium silicate solution with a concentration of 20 g / L (calculated as SiO2), adjust the pH to 6.5 with 0.1 mol / L hydrochloric acid solution, and let it stand for 10 min to obtain monosilicic acid mother liquor.

[0068] S3: Mix the nano zinc oxide dispersion with the monosilicic acid mother liquor and bring the volume to 30 L to obtain foliar fertilizer III.

[0069] Preparation Example 5: Preparation of Foliar Fertilizers I-III In this preparation example, the formulation of foliar fertilizer I is as follows: 80 mg / L nano zinc oxide (particle size 45~55 nm) (calculated as Zn), 65 mg / L nano SiO2, Tween-80 0.01% v / v, and deionized water as the solvent. Foliar fertilizer I is prepared according to the following steps: S1: Take 2.4 g (calculated as Zn) of nano zinc oxide with a particle size of 45~55 nm, add 3 L of 35℃ deionized water, then add 3 mL of Tween-80, and sonicate for 30 min to obtain nano zinc oxide dispersion.

[0070] S2: Take 1.95 g of nano SiO2, add 97.5 mL of 35℃ deionized water, and ultrasonically disperse for 30 min to obtain nano SiO2 dispersion.

[0071] S3: Mix the nano zinc oxide dispersion with the nano SiO2 dispersion and bring the volume to 30 L to obtain foliar fertilizer I.

[0072] In this preparation example, the formulation of foliar fertilizer II is as follows: 100 mg / L nano zinc oxide (particle size 30-40 nm) (calculated as Zn), 65 mg / L nano SiO2, 0.01% v / v Tween-80, and deionized water as the solvent. Foliar fertilizer II is prepared according to the following steps: S1: Take 3.0 g (calculated as Zn) of nano zinc oxide with a particle size of 30~40 nm, add 3 L of 35℃ deionized water, then add 3 mL of Tween-80, and sonicate for 30 min to obtain nano zinc oxide dispersion.

[0073] S2: Take 1.95 g of nano SiO2, add 97.5 mL of 35℃ deionized water, and ultrasonically disperse for 30 min to obtain nano SiO2 dispersion.

[0074] S3: Mix the nano zinc oxide dispersion with the nano SiO2 dispersion and bring the volume to 30 L to obtain foliar fertilizer II.

[0075] In this preparation example, the formulation of foliar fertilizer III is as follows: 120 mg / L nano zinc oxide (particle size 15~25 nm) (calculated as Zn), 65 mg / L nano SiO2, 0.01% v / v Tween-80, and deionized water as the solvent. Foliar fertilizer III is prepared according to the following steps: S1: Take 3.6 g (calculated as Zn) of nano zinc oxide with a particle size of 15~25 nm, add 3 L of 35℃ deionized water, then add 3 mL of Tween-80, and sonicate for 30 min to obtain nano zinc oxide dispersion.

[0076] S2: Take 1.95 g of nano SiO2, add 97.5 mL of 35℃ deionized water, and ultrasonically disperse for 30 min to obtain nano SiO2 dispersion.

[0077] S3: Mix the nano zinc oxide dispersion with the nano SiO2 dispersion and bring the volume to 30 L to obtain foliar fertilizer III.

[0078] Application Example 1: Artificial Spraying Experiment of Nanjing 46 Direct-Seeded Rice 1.1 Test Conditions Experimental location: Rice experimental field in Linping District, Hangzhou City, Zhejiang Province.

[0079] Soil conditions: loam, pH 6.2, organic matter 18.5 g / kg, available zinc 0.8 mg / kg.

[0080] Planting method: direct seeding in water, seeding rate 3.5 kg / 667 m² 2 The sowing date is May 20th.

[0081] Experimental design: Six treatments were set up, with each treatment replicated three times, and the plot area was 20 m². 2 The blocks were randomly arranged, with 50 cm isolation rows between blocks (for non-experimental rice).

[0082] Experimental treatments: CK group was sprayed with water; T1 group was treated with foliar fertilizers I-III from Preparation Example 1 (sprayed three times according to gradient particle size and concentration); T2 group was treated with foliar fertilizers I-III from Preparation Example 2 (sprayed with fixed particle size and concentration); T3 group was treated with foliar fertilizers I-III from Preparation Example 3 (sprayed with fixed particle size and gradient concentration); T4 group was treated with foliar fertilizers I-III from Preparation Example 4 (sprayed with gradient particle size and fixed concentration); T5 group was treated with foliar fertilizers I-III from Preparation Example 5 (sprayed with nano-SiO2 instead of monosilicic acid).

[0083] 1.2 Implementation Steps Field preparation: Apply 1200 kg / 667 m² of well-rotted organic fertilizer before sowing. 2 Base application of urea 15 kg / 667 m 2 30 kg / 667 m³ of superphosphate 2 and potassium chloride 10 kg / 667 m 2 After plowing and harrowing, the soil is irrigated and then sown.

[0084] Application procedures: The first application was on July 25th (early booting stage, young spikelets 1-2 cm long). The control group was sprayed with water, while groups T1-T5 were sprayed with foliar fertilizer I (prepared in Examples 1-5). The second application was on July 28th (rapid spikelet elongation stage, young spikelets 3-5 cm long). The control group was sprayed with water, while groups T1-T5 were sprayed with foliar fertilizer II (prepared in Examples 1-5). The third application was on July 31st (from pollen mother cell meiosis to microspore formation stage). The control group was sprayed with water, while groups T1-T5 were sprayed with foliar fertilizer III (prepared in Examples 1-5). Each application was carried out at 9:00 AM (cloudy days) or 5:30 PM (sunny days) using a backpack electric sprayer, with the nozzle facing upwards, evenly spraying both sides of the flag leaf and the second leaf from the top. The spray volume was 30 L / 667 m³. 2 (Based on soil area).

[0085] Field management: Apply 10 kg / 667 m² of urea during the tillering stage. 2 Top-dress with 5 kg / 667 m³ of urea during the jointing stage. 2 and potassium chloride 15 kg / 667 m 2 Pest and disease control is the same as usual (solar insecticidal lamp + Jinggangmycin to prevent sheath blight).

[0086] Harvesting and Testing: Harvesting took place on October 25th. Yield, thousand-grain weight, and seed setting rate were measured, and the zinc content of the grains was determined by atomic absorption spectrophotometry.

[0087] 1.3 Test Results The experimental results of the CK group and the T1~T5 groups are shown in Table 1.

[0088] Table 1 Results of artificial spraying experiment on Nanjing 46 direct-seeded rice Application Example 2: Unmanned Aerial Vehicle (UAV) Spraying Experiment of Nanjing 46 Direct-Seeded Rice 2.1 Test Conditions Experimental location: Feixi Experimental Base, Rice Research Institute, Anhui Academy of Agricultural Sciences; Soil conditions: clay loam, pH 6.8, organic matter 22.3 g / kg, available zinc 1.2 mg / kg.

[0089] Planting method: direct seeding with irrigation water, seeding rate 3.2 kg / 667 m² 2 Sowing date: May 18th.

[0090] Experimental design: Six treatments were set up, each covering 10 acres, for large-area comparison.

[0091] Experimental treatments: The control group (CK) was sprayed with water; the T1 group used foliar fertilizers I-III from Preparation Example 1 (sprayed three times according to gradient particle size and concentration), with 0.03% v / v Silwet L-77 added to improve the low-volume droplet distribution of the drone; the T2 group used foliar fertilizers I-III from Preparation Example 2 (sprayed at fixed particle size and concentration), with 0.03% v / v Silwet L-77 added to improve the low-volume droplet distribution of the drone; the T3 group used foliar fertilizers I-III from Preparation Example 3 (sprayed at fixed particle size and gradient concentration), with 0.03% v / v Silwet L-77 added to improve the low-volume droplet distribution of the drone; the T4 group used foliar fertilizers I-III from Preparation Example 4 (sprayed at gradient particle size and fixed concentration), with 0.03% v / v Silwet L-77 added to improve the low-volume droplet distribution of the drone. Silwet L-77 improves the low-volume droplet spreadability of drones; Group T5 uses foliar fertilizers I~III from Preparation Example 5 (replacing monosilicic acid with nano-SiO2 for spraying), and adds 0.03% v / v Silwet L-77 to improve the low-volume droplet spreadability of drones.

[0092] 2.2 Implementation Steps The first spraying was on July 22 (early booting stage, young spikelets 1-2 cm long). The CK group was sprayed with water, while the T1-T5 groups were sprayed with foliar fertilizer I (preparation examples 1-5) containing 0.03% v / v Silwet L-77. The second spraying was on July 25 (rapid spikelet elongation stage, young spikelets 3-5 cm long). The CK group was sprayed with water, while the T1-T5 groups were sprayed with foliar fertilizer II (preparation examples 1-5) containing 0.03% v / v Silwet L-77. The third spraying was on July 28 (from pollen mother cell meiosis to microspore formation stage). The CK group was sprayed with water, while the T1-T5 groups were sprayed with foliar fertilizer III (preparation examples 1-5) containing 0.03% v / v Silwet L-77. Each spraying operation utilizes a multi-rotor agricultural drone (payload 12 L), flying at an altitude of 1.8 m and a speed of 4 m / s, with a spray volume of 12 L / 667 m³. 2 (Based on soil area), the volume median diameter (VMD) of the droplets is 150 μm.

[0093] Field management: Apply 1 kg of zinc sulfate per 667 m² as basal fertilizer. 2(For basal fertilizer application only, not a substitute for foliar zinc); Top-dress with urea at the tillering stage: 10 kg / 667 m² 2 Top-dress with 5 kg / 667 m³ of urea during the jointing stage. 2 and potassium chloride 15 kg / 667 m 2 Pest and disease control is the same as usual (solar insecticidal lamp + Jinggangmycin to prevent sheath blight).

[0094] Harvesting and Testing: Harvesting took place on October 22nd. Yield was measured, and the zinc content of the grains was determined using atomic absorption spectrophotometry.

[0095] 2.3 Test Results The experimental results of the CK group and T1~T5 groups are shown in Table 2.

[0096] Table 2 Results of drone spraying test on Nanjing 46 direct-seeded rice The experimental results in Tables 1 and 2 are consistent: the zinc content and yield of grains in groups T2-T5 were higher than those in the control group, but the increase was relatively small; group T1 further improved the zinc content and yield of grains compared to groups T2-T5, with the zinc content reaching 75% and the yield increasing by 6.5-7.2%. These results indicate that this invention, by using nano-zinc oxide with decreasing particle size and increasing concentration in stages (early booting stage, rapid spikelet elongation stage, and pollen mother cell meiosis to microspore formation stage), and by compounding a specific silicon source (monosilicon) with each application, can overcome the zinc-rich bottleneck in Nanjing 46 varietal, significantly increasing its yield. Furthermore, it is compatible with both manual and drone operations, requiring no changes to existing agronomic processes, and possesses good scalability and industrialization prospects.

Claims

1. A method for fortifying zinc nutrition in rice based on Zn-Si compound foliar fertilizer, characterized in that, include: During rice cultivation, foliar fertilizers I to III were sprayed onto rice leaves at the early booting stage, the rapid elongation stage of young panicles, and the stage from pollen mother cell meiosis to microspore formation. Foliar fertilizers I to III all contain nano zinc oxide and monosilicic acid. The particle sizes of nano zinc oxide in foliar fertilizers I to III are 45-55 nm, 30-40 nm, and 15-25 nm, respectively; the rice variety is Nanjing 46.

2. The method for fortifying rice with zinc according to claim 1, characterized in that, The rice is cultivated by direct seeding.

3. The method for fortifying rice with zinc according to claim 1, characterized in that: In the foliar fertilizer I, the content of nano zinc oxide (calculated as Zn) is 70~90 mg / L, and the content of monosilicic acid (calculated as SiO2) is 50~80 mg / L; In the foliar fertilizer II, the content of nano zinc oxide (calculated as Zn) is 90~110 mg / L, and the content of monosilicic acid (calculated as SiO2) is 50~80 mg / L; The foliar fertilizer III contains 110-130 mg / L of nano zinc oxide (Zn) and 50-80 mg / L of monosilicic acid (SiO2).

4. The method for fortifying rice with zinc according to claim 1, characterized in that, Foliar fertilizers I to III also contain surfactants at a content of 0.01 to 0.05% v / v; the surfactants include Tween-20 and / or Silwet L-77.

5. The method for fortifying rice with zinc according to claim 1, 3, or 4, characterized in that, The solvent in foliar fertilizers I to III is water.

6. The method for fortifying rice with zinc according to claim 1 or 3, characterized in that, The preparation steps of the foliar fertilizers I to III include: dispersing nano zinc oxide in water to obtain a nano zinc oxide dispersion; adding hydrochloric acid solution to a potassium silicate solution until the pH is 6.2 to 6.8, and after complete hydrolysis, obtaining a monosilicic acid mother liquor; and mixing the nano zinc oxide dispersion with the monosilicic acid mother liquor.

7. The method for fortifying rice with zinc according to claim 1, characterized in that, The initial stage of spikelet development is when the young spikelet reaches a length of 1-2 cm or 7-10 days after the main stem elongates; the rapid elongation period of the young spikelet is when the young spikelet reaches a length of 3-5 cm; the period from pollen mother cell meiosis to microspore formation is 5-7 days before heading.

8. The method for fortifying rice with zinc according to claim 1, characterized in that, Foliar fertilizer application processes I through III were all carried out on sunny evenings, with a spray volume of 10-30 L / 667 m³. 2 .

9. The application of the zinc nutrient fortification method for rice according to any one of claims 1 to 8 in the cultivation of Nanjing 46 rice.

10. The application according to claim 9, characterized in that, The method for fortifying rice with zinc is used to improve the zinc content, yield, number of tillers, number of grains per panicle, or seed setting rate of Nanjing 46 rice.

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