A Rice Cultivation Method for Preventing Glume Malformation and Incomplete Closure

Abstract

This invention discloses a rice cultivation method for preventing malformed and unclosed glume, including rational straw return to the field, timely transplanting, optimized water management, and integrated pest management. Based on the inventors' research conclusion that "malformed and unclosed glume" is caused by allelopathic substances produced by the anaerobic decomposition of soil organic carbon before and after rice floret differentiation, this invention controls and reduces the accumulation of allelopathic substances produced by the anaerobic decomposition of soil organic carbon and the amount absorbed by the rice plant, and enhances the rice plant's ability to harmlessly utilize allelopathic substances. This reduces the numerous negative impacts of allelopathic substances on rice growth, development, and high yield, including preventing malformed and unclosed glume, thereby further increasing rice yield. This has significant practical implications for promoting rational straw return to the field and promoting the sustained growth of rice yield per unit area in my country.

Description

Technical Field

[0001] This invention relates to the field of rice cultivation technology, specifically to a rice cultivation method for preventing abnormal and unclosed glumes. Background Technology

[0002] The disease causing "malformed and unclosed glume" in rice, also known as "green standing disease" or "drought-induced green standing disease," was first reported in Japan in 1894. The earliest related report in my country appeared in 1960, and for the next 30 years, there were only sporadic reports. However, in the last thirty years, the occurrence of rice "unclosed glume" disease has become increasingly widespread, and its impact on rice yield in my country has become increasingly significant. Mildly affected fields generally experience yield reductions of 10-30%, while severely affected fields see yields drop to below 250 kg / mu or even complete crop failure. According to data, from 2005 to 2008, the area affected by "deformed and unclosed husks" disease in rice in Anhui Province reached 1.8 million mu, resulting in a reduction of 275,000 tons of rice and economic losses of 405 million yuan. In Huai'an City, the affected area in 2017 and 2020 exceeded 300,000 mu and 550,000 mu respectively, accounting for 6.7% and 11.9% of the city's total rice area in those years. A farmer in Huanghuatang Town, Xuyi County, suffered near-total crop failure for three consecutive years due to this disease.

[0003] Symptoms and manifestations of "malformed and unclosed glume" disease in rice: (1) Symptoms of diseased grains. Some glumes are short, flat, twisted, and deformed, with some outer glume tips bent and tilted towards the top of the inner glume, failing to close; some inner glumes become needle-like or even only the outer glume remains; some glumes are significantly elongated or even equal in length to the inner and outer glumes; some inner and outer glumes are twisted, causing the grains to become black and small; some inner and outer glumes are fused together but still produce normal grains; some inner and outer glumes are normal in shape and size but do not close; some are twin florets with only two outer glumes remaining. (2) Symptoms of diseased panicles. In mildly diseased panicles, there are only 1-5 diseased grains with "malformed and unclosed glumes," while the rest are healthy grains with normal glumes and normal flowering and fruiting. In some severely diseased panicles, the branches and florets are largely degenerated, with only a few florets with malformed glumes. In some severely diseased panicles, the number of primary and secondary branches and florets is not significantly different from that of healthy panicles, but all of them are diseased grains with "malformed and unclosed glumes." Some severely diseased panicles show a severely distorted shape. Some severely diseased panicles have branch panicles that are healthy panicles without a single diseased grain. (3) Manifestations of diseased plants. In appearance, diseased plants are not significantly different from healthy plants before the end of the booting stage. Afterward, the leaf color gradually darkens compared to healthy plants, sometimes accompanied by difficulty in heading and branching panicles. Among more than ten panicles on the same rice plant, those adjacent to the field ridge may all be healthy panicles without a single diseased grain, while those away from the field ridge may all be severely diseased panicles with "malformed and unclosed glumes." (4) Manifestations of diseased fields. Currently, the disease is no longer limited to late rice or early rice, or single-season late indica rice, nor is it limited to white soil fields, clear white soil fields, sandy ginger black soil, or dry-to-paddy fields. In some fields, the disease is present on the raised areas but not in the concave areas; in other fields, the disease is present on the concave areas but not in the raised areas; in some fields, the disease is present only at the field edges; in other fields, the disease is present everywhere except at the field edges; and in some fields, the disease is present in an irregular pattern. In fields that never develop the disease, a 50cm deep pit will cause the disease to develop after the pit is filled with topsoil around the pit. Fields that frequently develop the disease will definitely not develop the disease again after removing a topsoil layer of ≥10cm thickness. Fields with severe disease may not necessarily develop the disease again in the future.

[0004] Many hypotheses have been proposed regarding the etiology of rice "malformed and unclosed glume" disease: arsenic poisoning hypothesis, extreme high temperature hypothesis from booting to heading stage hypothesis, zinc or boron deficiency hypothesis, soil barrier hypothesis, rapid changes in soil moisture supply from floret differentiation to heading and flowering stage hypothesis, phytotoxicity hypothesis from multiple herbicides hypothesis, heavy metal contamination hypothesis, etc. However, no report attributes it to the toxic effects of allelochemicals produced by the decomposition of soil organic carbon under facultative anaerobic conditions. In the past thirty years, with the improvement of farmers' living standards, changes in cooking fuel, and increased crop yields in my country, the amount of crop straw directly returned to the field has been continuously increasing across the country. Returning all straw to the field in situ has become the new normal—increasingly widespread and continuously implemented year after year. In other words, in the present era, the external input of soil organic carbon has increased rapidly and unprecedentedly, breaking the original balance between input and decomposition that has been maintained for a long time. For example, in the topsoil of wheat-rice rotation fields in northern Jiangsu, when rice is transplanted, there are not only 500-750 kg / mu of the root stubble and straw of the previous wheat crop, but also 200-300 kg / mu of undecomposed straw residue from the rice crop before that.Based on previous research, soil organic carbon decomposition, including the decomposition of crop straw after returning it to the field, is a complex microbiological process. The decomposition rate and products are influenced by numerous factors, including temperature, moisture, soil conditions, and cultivation practices. The decomposition rate increases exponentially with increasing temperature, showing a highly significant correlation. The types and quantities of soil organic carbon decomposition products are affected by oxygen supply, soil fertility, and pH. Under oxygen-rich conditions, the final decomposition products are inorganic molecules such as water and CO2, and no intermediate decomposition products accumulate. However, under facultative and anaerobic conditions, a variety of small-molecule decomposition products accumulate in large quantities. Lignin, a major component of crop straw, is the most difficult to decompose and cannot decompose at all under anaerobic conditions. However, under high temperatures above 33°C and facultative anaerobic conditions, phenolic substances accumulate in large quantities. Phenolic substances are widely present in plants and soil, accounting for 2.1–4.4% of the root dry weight in monocotyledonous plants, and reaching a maximum content of 2.6% in the topsoil. g / kg; Over 98% of phenolic substances in soil exist in a complex state adsorbed by soil colloids, insoluble in water and unable to be absorbed by plants. The toxic substances to plants are the water-soluble, free-form phenolic substances that can be absorbed by plants. These are the most studied, recognized, and highly active allelochemicals, exhibiting a significant inhibitory effect on plant growth, inhibiting seed germination, affecting membrane system function, photosynthesis and respiration, protective enzyme activity, endogenous hormone function, mineral ion absorption, and rhizosphere microbial flora and activity, and can also lead to root tip malformation. Free-form phenolic substances dissolved in soil water form temporary complexes with mineral ions, which are extremely unstable and constantly undergoing dynamic changes, including degradation, polymerization, and mineralization. Phenolic substances are adsorbed by soil particles. When the concentration of free total phenols in the soil is high, most are rapidly degraded by soil microorganisms, while some are adsorbed by soil humus and mineral colloids, becoming complex phenols. Therefore, the content of free total phenols in the topsoil is generally only 18-60 mg / kg soil, which is insufficient to cause physiological toxicity to crops (for rice, ≥200 mg / kg soil). Only during field soaking and tillage operations and the following 10 days can the content of free total phenols in the soil exceed 200 mg / kg soil. Phenolic substances that enter plants are normally rapidly synthesized into glycosides that are non-toxic to protoplasm, and then transported and utilized by plants. However, if plants are under drought stress or have poor root growth, they cannot synthesize glycosides in time, thus causing toxicity to protoplasm. In addition to phenolic substances, many other types of allelochemicals are also recognized products of facultative or anaerobic decomposition of soil organic carbon and are widely present in plants. However, no research reports have yet been published regarding whether phenolic substances or other products of facultative or anaerobic decomposition of soil organic carbon have a negative impact on the differentiation and development of rice spikelets.

[0005] From 2016 to 2022, the inventors' team conducted a special experiment on the disease "malformed and unclosed glume" in rice at multiple locations. The results are as follows:

[0006] (1) Results of continuous monitoring of typical fields in 2016: In Yangzhuang Village, Huanghuatang Town, Xuyi County, hybrid indica rice grown after wheat stubble frequently suffered from "malformed and unclosed glume" disease. The soil was yellow-brown soil, with normal levels of available zinc and boron, and arsenic content far below the national standard limit. The inventors continuously monitored the rice from the day of planting (June 4th) to the full bloom stage (August 10th). Among the 17 rice fields monitored, 6 fields were found to have "malformed and unclosed glume" disease. (1) Common characteristics of diseased rice fields are delayed drying and re-irrigation (early panicles over 2mm in length are still not re-irrigated). In low-lying fields, all rice plants except those along the field edges are severely affected, while in high-lying fields, diseased rice plants are only distributed within 50cm of the edge of the steep slope. Rice fields that maintain a water layer after transplanting, where the topsoil still resembles black tofu during the spikelet differentiation stage, do not develop "malformed and unclosed glume" disease. (2) The earliest date for clearly identifiable malformed spikelets (July 22nd) is 15 days before heading, when the young panicle reaches 1.3cm in length. (3) "Malformed and unclosed glume" disease in rice is not closely related to whether or not wheat straw was returned to the field in the previous crop, or the amount of straw returned. Fields where wheat straw was not returned to the field or fallow stubble fields can also develop the disease. (4) Foliar application of zinc, boron, and potassium-containing fertilizers during the jointing stage significantly reduces the incidence of "malformed and unclosed glume" disease in rice panicles, and significantly increases the seed setting rate and yield.

[0007] (2) Rice plant uprooting and replanting experiment in 2017: ① In a sandy soil hybrid indica rice field in Dingji Town, Huaiyin District, Huai'an City, at the early stage of floret differentiation (July 23), two rice plants with similar height, leaf color, and tiller size and number were uprooted. Each rice plant had about 2.0 kg of yellow mud on its roots. After uprooting the first rice plant, 5g of wheat straw powder was first applied to the bottom of the root-mud mixture before it was put back into the original pit. After uprooting the second rice plant, it was put back into the original pit directly. The field was kept with a water layer for the next 20 days. All the rice ears on the two rice plants were healthy and there were no diseased grains with "malformed and unclosed glumes". ② At the Jiangsu Province Rice and Wheat Science and Technology Comprehensive Demonstration Base (Huai'an City), in the silty soil, two hybrid indica rice plants that were similar in height, leaf color, and the size and number of tillers were pulled up at the early stage of spikelet differentiation (July 24). Each plant had about 2.5 kg of black mud on its root system. After the first plant was pulled up, 5 g of wheat straw powder was attached to the bottom of the root-mud mixture and wrapped in a waterproof plastic bag before it was planted in the paddy field. The second plant was pulled up and the root-mud mixture was wrapped in the same plastic bag before being planted in the paddy field. For the next 20 days, a water layer was maintained in the field. At 14:00 on July 27, the outdoor temperature was 37.0℃. There were still no visible differences between the two plants in terms of height, leaf color, and the size and number of tillers. However, the body temperature of the first plant was measured to be 35.6℃ using an infrared thermometer, and the body temperature of the second plant and the surrounding plants was 29.2℃. On August 18th, the first rice plant fully emerged with 5 panicles, each panicle containing 5-20 grains at the top due to "malformed and unclosed glume." The second rice plant fully emerged with 8 panicles, each healthy with no diseased grains or panicles. By August 25th, both plants had produced a total of 11 panicles, with 5 and 0 diseased panicles respectively. This means that on the fourth day after treatment, the rice plants that developed "malformed and unclosed glume" had a body temperature 6.4℃ higher than normal rice plants. ③ In a machine-transplanted paddy field in Maba Town, Xuyi County, with yellow-brown soil and a daily infiltration rate of 3-5 mm, four hybrid indica rice plants similar in height, leaf color, and the size and number of tillers were pulled up on July 25th at the three-leaf stage from the top. Each plant had about 2.0 kg of black mud around its roots. 50 g of fine wheat straw powder was sprinkled on a 30cm x 40cm patch of the field near the edge and repeatedly trampled to mix the powder into the black mud. The four plants were then planted in this mud. The field was irrigated two days later and the water level was maintained. On September 20th, it was observed that three of the four plants had mildly diseased panicles with "malformed and unclosed husks," and all the panicles on the main stem were diseased, with 5-15 diseased grains on each panicle.

[0008] (3) 2017 Paddy Field Re-watering Experiment: Jiangsu Provincial Rice and Wheat Science and Technology Comprehensive Demonstration Base (Huai'an City). The content of heavy metals and arsenic in the soil was within the limits of national standards. The full return of rice and wheat straw to the field was continuously implemented. At the time of rice transplanting, the total amount of previous crop wheat roots and straw, as well as the residue of the previous crop rice straw in the soil, was ≥850 mg / L. kg / mu, in the western 10 mu of field No. 9, 58 conventional japonica rice varieties with different growth periods were displayed, including Nanjing 2728, Lianjing 12, Longjing 968, Huaidao 20, Jinjing 818, Yangjing 239, Huzao Ruanjing, Suxiu 867, Shengdao 18, and Runnong 4. The fields were not brought under actual drying conditions in late July, and the fields were dried from August 10 to 12 until the field surface turned white and no marks were left when stepped on. The heading date ranged from August 20 to September 1. Samples were taken for seed testing on October 25. All 58 japonica rice varieties showed mild "malformed and unclosed hulls" diseased panicles.

[0009] (4) 2017 Severely Overaged Seedling Transplanting Experiment: Jiangsu Rice and Wheat Science and Technology Comprehensive Demonstration Base (Huai'an City), ① In the 4 mu east of field No. 9, which was a fallow stubble field, the straw from the previous crop was also completely removed from the field. The transplanting date of the second stage of hybrid indica rice seedlings Ke Liangyou 502 and Y Liang 900 was delayed to July 7, with a total seedling age of 63 days. 110 holes were planted for each variety. Not only did they all show uneven heading, but the heading date of the main stem panicle of each rice plant in each hole was from August 8 to 10, and the tillering panicle was from August 18 to 24. Moreover, the main stem panicle of each rice plant in each hole was a diseased panicle with "deformed and unclosed glumes". ② In the eastern 5 mu of field No. 7, the seedling age of early-maturing japonica rice seedlings was extended to 45 days and the transplanting date was delayed to June 28. Not only did the heading date of the main stem panicle be August 5 and the tillering panicle be August 25, but the main stem panicle of each rice plant was also a diseased panicle with "deformed and unclosed glumes".

[0010] (5) High-Temperature Experiments in Artificial Climate Chambers: From late July to early August 2018 to 2021 (the period before and after conventional japonica rice in Huaiyin District, Huai'an City entered the spikelet differentiation stage), a total of 23 experiments were conducted using artificial climate chambers to investigate the effects of high temperatures on the spikelet differentiation and development of rice. The chamber temperatures were set at four levels: 30℃, 35℃, 40℃, and 42℃. The light intensity and relative humidity inside the chambers were kept constant at 100% and 90%, respectively. Rice plants in the spikelet differentiation stage were pulled from the field and placed in shallow water troughs within the artificial climate chambers for 3-4 days. Those that survived were then replanted in the paddy fields. Results of the investigation during the flowering period: Regardless of whether the rice plants had soil around their roots or not, treatment at temperatures above 35℃ for 2-4 days would cause the growth of young rice panicles to stop, and treatment at 42℃ for 2 days would cause more than 60% of the rice plants to die. However, no cases of "malformed and unclosed glumes" appeared in rice panicles when the treatment temperature ranged from 30℃ to 42℃. If 5g of fine wheat straw powder was coated around the rice plant's root-soil mixture and then wrapped in a waterproof bag, rice plants treated at 30℃ for 4 days would subsequently develop "malformed and unclosed glumes," while rice plants treated at 35℃ for more than 2 days would all die.

[0011] (6) Potted Rice Plant Treatment Experiment: From 2018 to 2021, every year after July 20th (from the 5th leaf stage to the early 3rd leaf stage), 10-30 rice plants were pulled from the field of conventionally transplanted japonica rice variety Jinjing 818. Some plants retained root soil, while others did not. They were placed in 1.2 L transparent plastic cups and placed in the open space in front of the office building. They were checked and watered daily. The treatment agents included: fine wheat straw powder, wheat straw cooking liquid, wheat straw decomposition liquid, 2-5 mmol / L ferulic acid, 2 mmol / L cinnamic acid, 2 mmol / L sinapic acid, 2-10 mmol / L p-hydroxybenzoic acid, 2 mmol / L eugenol, 2 mmol / L p-coumaric acid, 2 mmol / L vanillic acid, 1 mmol / L benzoquinone, 1 mmol / L guaiacol, 1 mmol / L hydroquinone, 1 mmol / L hydroquinone, and 1 mmol / L phloroglucinol. After treatment, the rice plants were replanted in the field, and the results were investigated during the grain-filling stage: ① Wheat straw powder. Treating rice plants with retained root soil using a large amount of wheat straw powder, starting from the 4th leaf stage from the top, caused the flag leaf to wither or turn yellow before it even emerged. Treating starting from the 3rd leaf stage from the top resulted in "malformed and unclosed glumes" in the panicles, but only 1-5 grains were diseased. ② Wheat straw cooking liquid and decomposition liquid. These had a significant inhibitory effect on rice plant growth, but no "malformed and unclosed glumes" were observed in the panicles. ③ Phenolic substances. Treating rice plants with different doses of the above phenolic substances, even with extremely high doses that caused the rice plants to rapidly fade in color or even approach death, did not result in "malformed and unclosed glumes" in the panicles. The dosage required to cause rapid fading of rice plant leaf color varied depending on the phenolic substance. Sinic acid, cinnamic acid, and ferulic acid required smaller doses, while p-hydroxybenzoic acid required a much larger dose. It is important to emphasize that pot experiments have a fatal flaw. Regardless of the amount of soil, the pot environment is significantly more conducive to the root growth of rice plants, making it extremely difficult to simulate the soil environment of paddy fields, especially the redox potential and its dynamic changes in paddy field soil. The types, forms, and quantities of most compounds present in the soil change with the redox potential of the soil, and free phenolic substances in the soil are no exception.

[0012] (7) Field injection experiment of phenolic substances: From 2018 to 2022, each year at the end of July or beginning of August when rice entered the second leaf stage from the bottom, rice plants in the first 1-2 rows at the edge of the field were selected. These included both hybrid indica and conventional japonica rice. ① First, the leaf sheath of the third leaf from the bottom was peeled away, and the leaf heart (containing the leaf of the second leaf from the bottom, leaf sheath, and flag leaf) was removed. Then, 200-500 μL of phenolic substances (the types and concentrations of phenolic substances were the same as above, and the same applies below) were injected into the cavity using a 1 ml syringe. ② 200-500 μL of phenolic substances were injected into the cavity of the first elongated internode using a 1 ml syringe. ③ The leaf heart was removed, and 200-500 μL of phenolic substances were injected into the cavity of the young panicle and the cavity of the first elongated internode using a 1 ml syringe. More than 2500 effective panicles were treated over the four years. After all the rice panicles had emerged, the results of the treatment were as follows: Only one diseased panicle with a normal but not closed glumes appeared in the cinnamic acid treatment in 2019; the remaining 2,500-plus treated panicles, which emerged under the condition of water layer in the field on the day of treatment, were all healthy and normal, but often branched panicles. On the day of treatment, the field was still under the condition of severe baking with white and large cracks, and none of them produced panicles. The length of the dead young panicles was similar to that on the day of treatment. The control rice plants, which were also under the condition of severe baking with white and large cracks at the same time, all produced healthy panicles, although a large number of florets degenerated on some panicles.

[0013] The inventors' above-mentioned experimental results indicate that only two conditions are necessary for the occurrence of rice "malformed and unclosed glume" disease: first, sufficient organic carbon in the soil; and second, the rice plants at the floret differentiation stage must either be in a state of scorched soil, or have just emerged from severe stunting or have just recovered to normal. In other words, rice plants at the floret differentiation stage absorb a large amount of allelochemicals produced by the anaerobic decomposition of soil organic carbon, exceeding the plant's own capacity for harmless utilization, thus becoming poisoned. Therefore, the inventors believe that rice "malformed and unclosed glume" disease is caused by allelochemical poisoning from the anaerobic decomposition of soil organic carbon around the floret differentiation stage. This completely rules out the extreme high temperature hypothesis from booting to heading stage, the hypothesis of drastic changes in soil water supply from floret differentiation to heading and flowering stage, the hypothesis of zinc or boron deficiency in the soil, and the soil barrier hypothesis. Heavy metal contamination, arsenic poisoning, and phytotoxicity from multiple herbicides are only contributing factors in individual fields. Furthermore, in today's era where large amounts of external organic carbon are continuously input into the soil, there is no need for continuous and uninterrupted crop straw return to the field. The amount of organic carbon in the soil is sufficient to cause severe occurrence of "malformed and unclosed glumes" disease in rice. The toxic effects of soil organic carbon facultative anaerobic decomposition products on rice are not limited to rice florets. Symptoms of poisoning in the flag leaf include withering and death when the tip emerges or natural damage in a certain part. The symptom that can be detected in the early stage of diseased rice plants in the field is an abnormally high body temperature of the diseased plant.

[0014] Based on the inventors' research findings, an innovative targeted cultivation plan was proposed to guide my country's rice production in adopting effective comprehensive prevention and control measures. This plan corrects some previous unreasonable practices, reduces the accumulation of organic carbon and anaerobic allelochemicals in paddy field soil, as well as the absorption by rice plants, and enhances the rice plants' ability to harmlessly utilize allelochemicals. This, in turn, reduces the numerous negative impacts of allelochemicals on rice growth, development, and high yield formation, minimizing the probability and severity of "malformed and unclosed husk" disease in Chinese rice, further promoting the increase of rice yield per unit area, and achieving a virtuous cycle of land use and soil conservation. This has significant practical implications for ensuring my country's food security and social stability. Summary of the Invention

[0015] The technical problem this invention aims to solve is: based on the inventors' research conclusion that rice "malformed and unclosed glume" disease is caused by allelopathic substances produced by the anaerobic decomposition of soil organic carbon before and after the floret differentiation period. This invention controls and reduces the accumulation of allelopathic substances produced by the anaerobic decomposition of soil organic carbon and the amount absorbed by rice plants, and enhances the rice plants' ability to harmlessly utilize allelopathic substances. This reduces the numerous negative impacts of allelopathic substances on rice growth, development, and high yield, including preventing the occurrence of "malformed and unclosed glume" disease, thereby further increasing rice yield.

[0016] This invention is achieved through the following technical solution:

[0017] A method for preventing rice hull malformation and incomplete closure includes:

[0018] (1) Reasonable return of straw to the field: Straw should be mechanically shredded and returned to the field after the previous crop harvest, with the length of the shredded straw required to be ≤5cm. The amount of straw returned to the field, the depth of return, and the total number of water-tillage and harrowing operations should be determined based on the soil's permeability. Specifically, when the daily permeability of the paddy field is ≥20mm, 6-19mm, or ≤5mm, the amount of straw returned to the field should be ≤750kg / mu, ≤700kg / mu, or ≤500kg / mu respectively; the straw return depth should be ≤18cm, ≤15cm, or ≤10cm respectively; and the total number of water-tillage and harrowing operations should be ≤4 times, ≤3 times, or 1 time respectively. During the rice tillering stage, dig a field drainage system. The distance between the perimeter ditch and the surrounding field ridges should be ≤65cm. Dig one furrow ditch every 4-5m and one side ditch every 20m, with a depth ≥12cm, ensuring that all ditches are interconnected and irrigation and drainage are unobstructed.

[0019] (2) Transplanting at the appropriate time: Plant seedlings of the appropriate age as early and shallowly as possible; it is strictly forbidden to transplant seedlings that have entered the estimated heading date within 45 days.

[0020] (3) Optimize water management: For small and medium-sized seedlings with soil attached, transplant with thin water. Keep the field surface moist before the seedlings recover and turn green. After draining the water from the ponds, irrigate once with a light watering. For large seedlings without soil attached, transplant with thin water. Keep the water layer shallow before the seedlings recover and turn green. After the seedlings recover, drain the water and expose the field to the elements for 1-3 days. During the tillering period, irrigate with a 3-5cm thick layer of water each time. After the water dries naturally, irrigate again after 1-2 days. The key to field drying is "time is crucial, don't wait for the seedlings." Drain the water immediately 45 days before the estimated heading date. If there is heavy rain during the drying period, drain the accumulated water promptly. The drying degree should be such that the field is not sinking and the soil is not sticky. Avoid drying the field to the point where the mud surface turns white and large cracks appear. Re-irrigate immediately 30 days before the estimated heading date. Avoid irrigating with deep water all at once. Irrigate once with a light watering, let it dry, and then establish a water layer after 1 day. During the jointing to flowering stage, irrigate frequently with shallow water. During the grain-filling and hardening stage, keep the field moist but not waterlogged, gradually increasing the interval between the first and second irrigations. In case of temperatures ≥33℃ or ≤22℃, irrigate with a water layer ≥7cm thick. Depending on soil characteristics, stop irrigation 15–7 days before maturity.

[0021] (4) Comprehensive prevention and control.

[0022] Furthermore, in step (1) reasonable return to the field, specifically, the further improvement plan is that when the daily seepage of the paddy field is ≤5mm, it is required to dry-plow and dry-prepare before irrigation and harrowing, and the operation quality should reach "fine soil and flat field surface"; for paddy fields with blank stubble and loose stubble connection, it is recommended to plow and dry the soil for a period of time.

[0023] Furthermore, in step (4) comprehensive prevention and control, specifically, for fields where "malformed and unclosed glumes" have occurred, avoid excessive application of nitrogen fertilizer and excessive chemical nitrogen fertilizer in basal and tillering fertilizers, increase the application of microbial fertilizers that promote the harmless decomposition of straw in basal and surface fertilizers, increase the application of potassium fertilizers in tillering fertilizers, and require the application of foliar fertilizers containing zinc, boron, silicon and other components after jointing. Within 7 days before and after spraying herbicides, it is strictly forbidden to spray organophosphorus insecticides; it is strictly forbidden to use excessive amounts of foliar herbicides, and chemical control is prohibited after jointing. For fields where stunted seedlings appear during the tillering stage, immediately dehydrate and expose the field, and spray foliar fertilizers containing phosphorus and zinc and biostimulants. In the event of high temperatures above 33℃, chemical control requires "no excessive use of pesticides, sufficient water, a water layer in the field, and an interval of more than 5 days between two sprays".

[0024] Compared with existing technologies for preventing glume deformity and incomplete closure, this invention has the following two significant advantages:

[0025] 1. This invention is highly targeted. Based on the inventor's own research conclusion—that rice "malformed and unclosed glume" disease is caused by allelopathic substances produced by the anaerobic decomposition of soil organic carbon before and after the floret differentiation period—this invention innovatively proposes a targeted cultivation scheme to guide rice production in my country. By controlling and reducing the accumulation of allelopathic substances from the anaerobic decomposition of soil organic carbon and the amount absorbed by rice plants, and enhancing the rice plants' ability to harmlessly utilize allelopathic substances, this invention effectively reduces the probability and severity of rice "malformed and unclosed glume" disease, thereby promoting further increases in rice yield in my country.

[0026] 2. This invention has high yield potential. Based on the characteristics of paddy fields with different permeability, this invention implements measures such as rational return to the field, transplanting strong seedlings at the appropriate age, optimizing water management, increasing the application of fertilizers such as phosphorus, potassium, zinc, and boron, increasing the application of microbial fertilizers that promote the harmless decomposition of straw, and comprehensive prevention and control, so as to achieve robust rice plants and healthy rice populations in the field, which is conducive to further increasing rice yield per unit area. Detailed Implementation

[0027] Typical embodiments of this invention include: a machine-planted hybrid indica rice field on wheat stubble in the Taofanzhuang project area of ​​Gaojiayan Town, Huaiyin District, Huai'an City, part of the "Two New and Three Modernizations" project; and a hand-planted hybrid indica rice field on wheat stubble in Cao Yunfei's home in Dasheng Village, Mudian Town, Xuyi County, Huai'an City. The specific technical solutions are as follows:

[0028] (1) Reasonable return of straw to the field: Straw should be mechanically shredded and returned to the field after the previous crop harvest, with the length of the shredded straw required to be ≤5cm. The amount of straw returned to the field, the depth of return, and the total number of water-tillage and harrowing operations should be determined based on the soil's permeability. Specifically, when the daily permeability of the paddy field is ≥20mm, 6-19mm, or ≤5mm, the amount of straw returned to the field should be ≤750kg / mu, ≤700kg / mu, or ≤500kg / mu respectively; the straw return depth should be ≤18cm, ≤15cm, or ≤10cm respectively; and the total number of water-tillage and harrowing operations should be ≤4 times, ≤3 times, or 1 time respectively. During the rice tillering stage, specialized machinery should be used to dig field ditches. The distance between the perimeter ditch and the surrounding field ridges should be ≤65cm. One furrow ditch should be dug every 4-5m, and one side ditch every 20m, with a depth ≥12cm, ensuring that all ditches are interconnected and irrigation and drainage are unobstructed. When the daily seepage rate of paddy fields is ≤5mm, dry plowing and leveling are required before irrigation and harrowing, and the operation quality should reach "fine soil and flat field surface". For paddy fields with no crop rotation or loose crop rotation, it is recommended to plow and let the soil dry for a period of time.

[0029] (2) Transplanting at the appropriate time: Plant seedlings of the appropriate age as early and shallowly as possible; it is strictly forbidden to transplant seedlings that have entered the estimated heading date within 45 days.

[0030] (3) Optimize water management: For small and medium-sized seedlings with soil attached, transplant with thin water. Keep the field surface moist before the seedlings recover and turn green. After draining the water from the ponds, irrigate once with a light watering. For large seedlings without soil attached, transplant with thin water. Keep the water layer shallow before the seedlings recover and turn green. After the seedlings recover, drain the water and expose the field to the elements for 1-3 days. During the tillering period, irrigate with a 3-5cm thick layer of water each time. After the water dries naturally, irrigate again after 1-2 days. The key to field drying is "time is crucial, don't wait for the seedlings." Drain the water immediately 45 days before the estimated heading date. If there is heavy rain during the drying period, drain the accumulated water promptly. The drying degree should be such that the field is not sinking and the soil is not sticky. Avoid drying the field to the point where the mud surface turns white and large cracks appear. Re-irrigate immediately 30 days before the estimated heading date. Avoid irrigating with deep water all at once. Irrigate once with a light watering, let it dry, and then establish a water layer after 1 day. During the jointing to flowering stage, irrigate frequently with shallow water. During the grain filling and ripening stage, keep the field alternately dry and wet, and gradually increase the interval between the first and second irrigations. In case of high temperature ≥33℃ or low temperature ≤22℃, irrigate with a water layer ≥7cm thick. Depending on the soil characteristics, stop watering 15 to 7 days before maturity.

[0031] (4) Comprehensive Prevention and Control: For fields that have experienced "malformed and unclosed glume" disease, avoid excessive application of nitrogen fertilizer and excessive chemical nitrogen fertilizer in basal and tillering fertilizers. Increase the application of microbial fertilizers that promote the harmless decomposition of straw in basal and surface fertilizers, and increase the application of potassium fertilizers in tillering fertilizers. After jointing, spray foliar fertilizers containing zinc, boron, silicon, etc. Do not spray organophosphate insecticides within 7 days before or after herbicide application; do not overuse foliar herbicides, and prohibit chemical control after jointing. For fields with stunted seedlings during the tillering stage, immediately dehydrate and expose the field, and spray foliar fertilizers containing phosphorus and zinc, as well as biostimulants. In the event of temperatures above 33℃, chemical control requires "no excessive pesticide dosage, sufficient dilution with water, a water layer in the field, and an interval of more than 5 days between two sprays."

[0032] Results of the demonstration field:

[0033] 1. In 2023, a 152-mu (approximately 10.8 hectares) hybrid indica rice paddy in Taofanzhuang Project Area, Gaojiayan Town, Huaiyin District, Huai'an City, was planted using machine transplanting after wheat stubble. The soil was heavy clay with a daily infiltration rate of 10 mm. The previous crop of wheat straw was 500 kg / mu, and the soil was tilled to a depth of 15 cm using rotary tillage and mixed with the straw. The paddy was first plowed and leveled once, followed by irrigation. The variety was Su Liangyou No. 1, with a seeding rate of 25 g / tray and a seedling rate of 36 trays / mu. Machine transplanting took place from June 22nd to 25th, with seedlings aged 35-40 days. The row spacing was 30 cm and the plant spacing was 10 cm. Weed control was implemented using a two-stage chemical weeding method. The total fertilizer application per mu was 15 kg N, 6 kg P2O5, and 6 kg K2O. The nitrogen fertilizer was distributed as 50%, 30%, and 20% in the base fertilizer, tillering fertilizer, and heading fertilizer, respectively. The phosphorus and potassium fertilizers were distributed equally in the base fertilizer and jointing fertilizer. 400 kg of boron fertilizer was added to the base fertilizer. g / mu, Tianhui Fertilizer Steward (humic acid bacteria fertilizer, organic matter ≥22%, N+P2O5+K2O ≥12%, which can promote the harmless decomposition of straw) 10 kg / mu; spray 100ml / mu of Kule Easy-Moisturize (containing EDTA-Zn 100 g / l, P2O5 430 g / l, K2O 50 g / l) during the jointing stage, and spray 100ml / mu of Kule Full Crown (containing N 60g / l, P2O5 230 g / l, P2O3 70 g / l, K2O 300 g / l, which can promote grain filling) during the heading stage; expose the field after the seedlings have established themselves, and do not connect the previous irrigation during the tillering stage; drain and dry the field on July 14, and start re-irrigating on July 25; heading on August 26, and harvesting on October 25, with a total average yield of 650 kg / mu and 800 kg / mu for high-yield fields. According to the inventors' investigation, the demonstration field showed no cases of "malformed and unclosed glume" diseased panicles, while surrounding paddy fields that were still being dried in early August exhibited such diseased panicles, resulting in a rice grain filling rate below 80% and a yield below 650 kg / mu. A comparison of the two cultivation methods demonstrates that the present invention has a significant effect on preventing malformed and unclosed glume and promoting further increases in rice yield.

[0034] 2. Cao Yunfei's 33 mu (approximately 2.5 hectares) hand-planted hybrid indica rice field in Dasheng Village, Mudian Town, Xuyi County, Huai'an City in 2023: The soil is yellow-brown loam with a daily infiltration rate of 5 mm; the previous crop straw amount was 500 kg / mu (approximately 33.3 hectares), and the soil was mixed and returned to the field by rotary tillage to a depth of 10 cm. The field was first dry-plown and leveled, then irrigated. The variety was Hualiangyou 919, with rice seedlings harvested on May 2nd and hand-transplanted on June 15th, at an age of 45 days. The row spacing was 30 cm, the plant spacing was 20 cm, and there was one seedling per hill. Weed control was achieved using a closed-loop chemical weeding method. The total fertilizer application was 12 kg N / mu, 6 kg P2O5 / mu, and 6 kg K2O / mu. Nitrogen fertilizer was distributed as 60%, 30%, and 10% in the base fertilizer, tillering fertilizer, and panicle fertilizer, respectively. Phosphorus and potassium fertilizers were evenly distributed between the base fertilizer and the jointing fertilizer. 400 g / mu of boron fertilizer and Tianhui Fertilizer 10 were added to the base fertilizer. kg / mu; spray 100ml / mu of Coolle Easy Moisturizing during the jointing stage, and spray 100ml / mu of Coolle Full Crown during the heading stage; expose the field after the seedlings have established themselves, and do not connect the previous irrigation with the subsequent irrigation during the tillering stage; start drainage on July 12th and end field drying on July 24th; heading occurs on August 25th, and harvesting is completed on October 30th, with a total average yield of 900 kg / mu. According to the inventor's investigation, none of the demonstration fields had diseased panicles with "malformed and unclosed glumes," while in the surrounding rice fields using traditional cultivation techniques, due to the neglect of reasonable field return, timely field drying, and supplementation with micronutrients, a large number of fields had diseased panicles with "malformed and unclosed glumes," with the most severely affected fields experiencing complete crop failure. Comparing the two cultivation methods, it is evident that the present invention has a significant effect on preventing malformed and unclosed glumes and promoting further increases in rice yield.

Claims

1. A method for rice cultivation to prevent malformed and unclosed glumes, characterized in that, It includes the following steps: (1) Reasonable return of straw to the field: Rice hull malformation and incomplete closure disease is caused by allelopathic substances produced by the anaerobic decomposition of soil organic carbon before and after the floret differentiation period. Controlling the accumulation of allelopathic substances from soil organic carbon decomposition and the absorption by rice plants, and enhancing the rice plants' ability to harmlessly utilize allelopathic substances are crucial. During the previous crop harvest, straw should be mechanically shredded and returned to the field, requiring the shredded straw length to be ≤5cm. The amount of straw returned to the field, the depth of return, and the total number of water-tillage and harrowing operations should be determined based on the soil's permeability. Specifically, when the daily permeability of the paddy field is ≥20mm, 6-19mm, or ≤5mm, the amount of straw returned to the field should be ≤750kg / mu, ≤700kg / mu, or ≤500kg / mu, respectively, and the straw return depth should be ≤18cm, ≤15cm, or ≤10cm, respectively. cm, the total number of times of water-tilling and harrowing should be ≤4 times, ≤3 times, and 1 time respectively; dig field ditches during the rice tillering period, with the distance between the perimeter ditch and the surrounding field ridges ≤65cm, dig one furrow ditch every 4-5m, and dig one waist ditch every 20m, with a ditch depth ≥12cm, to ensure that the ditches are connected and irrigation and drainage are unobstructed. (2) Transplanting at the appropriate time: Plant seedlings of the appropriate age as early and shallowly as possible; it is strictly forbidden to transplant seedlings that have entered the period within 45 days before the estimated heading date; (3) Optimize water management: For small and medium-sized seedlings with soil attached, transplant with shallow water. Keep the field surface moist before the seedlings recover and turn green. After the water in the ponds is cut off, irrigate once with a quick watering. For large seedlings without soil attached, transplant with shallow water. Keep the water layer shallow before the seedlings recover and turn green. After the seedlings recover, drain the water and expose the field to the open for 1-3 days. During the tillering period, irrigate with a 3-5cm thick layer of water each time. After the water dries naturally, irrigate again after 1-2 days. For field drying, emphasize "time is of the essence, not seedlings." Drain the water immediately 45 days before the estimated heading date. If there is heavy rain during the field drying period, drain the water in time. The field drying should be done so that the water does not sink to the ground. The soil should be moist but not sticky; avoid drying the field to the point where the mud surface turns white and large cracks appear. Re-irrigate immediately 30 days before the estimated heading date, but avoid flooding with deep water all at once. First, irrigate briefly, and then establish a water layer one day after the water has dried. During the jointing to flowering stage, irrigate frequently with shallow water. During the grain filling and hardening stage, keep the field alternately dry and wet, and gradually increase the interval between the first and second irrigations. In case of high temperatures ≥33℃ or low temperatures ≤22℃, irrigate with a water layer ≥7cm thick. Depending on the soil characteristics, stop irrigation 15–7 days before maturity. (4) Comprehensive prevention and control.

2. The rice cultivation method for preventing malformed and unclosed glumes according to claim 1, characterized in that: Step (1) Return the soil to the field in a reasonable manner. Specifically, when the daily seepage of the paddy field is ≤5mm, it is required to dry-plow and dry-prepare the soil before irrigation and harrowing, and the quality of the operation should reach "fine soil and flat field surface".

3. The rice cultivation method for preventing malformed and unclosed glumes according to claim 1, characterized in that: Step (1) Return the rice to the field in a reasonable manner. Specifically, for rice fields with no stubble or loose stubble connections, it is recommended to plow and dry the soil for a period of time.

4. The rice cultivation method for preventing malformed and unclosed glumes according to claim 1, characterized in that: Step (4) Comprehensive prevention and control: Specifically, for fields where "malformed and unclosed glumes" disease has occurred, avoid excessive application of nitrogen fertilizer and excessive chemical nitrogen fertilizer in basal and tillering fertilizers. Apply microbial fertilizers that promote the harmless decomposition of straw to the basal and surface fertilizers, and apply potassium fertilizers to the tillering fertilizers. After jointing, it is required to spray foliar fertilizers containing zinc, boron, silicon and other components. It is strictly forbidden to spray organophosphorus insecticides within 7 days before and after spraying herbicides. It is strictly forbidden to use excessive amounts of foliar herbicides. Chemical control is prohibited after jointing. For fields where stunted seedlings appear during the tillering stage, immediately dehydrate and expose the field, and spray foliar fertilizers containing phosphorus and zinc and biostimulants. In the event of high temperatures above 33℃, chemical control requires "no excessive amount of pesticides, sufficient water, a water layer in the field, and an interval of more than 5 days between two sprays".