A method for cultivating rice with high-temperature resistance based on growth period regulation and integrated management

Abstract

This invention belongs to the field of rice cultivation technology, specifically involving a high-temperature resistant rice cultivation method based on growth period regulation and integrated management. Under single-sowing conditions, this method forms a leading peak grain-filling group and a backup relay group by controlling population density, regulating the timing of fertilizer and water during the tillering stage, and determining the group size. The middle group and the late-blooming group are truncated to control the time difference between the two flowering peaks to 5-7 days. When the high-temperature process overlaps with any flowering peak, a shallow water layer is maintained and potassium is supplemented during the heading stage and low-volume foliar potassium supplementation is carried out by drones. Subsequent maturity convergence management is implemented. This method can disperse the risk of high temperature during the heading and flowering stages, reduce high-temperature killing of males and high-temperature non-graining, improve the grain-filling rate, and take into account the feasibility of uniform maturity and harvest.

Description

Technical Field

[0001] This invention pertains to rice cultivation technology, specifically a method for cultivating rice to withstand high temperatures based on growth period regulation and integrated management. Background Technology

[0002] The heading and flowering stage of rice is a critical period determining the seed setting rate and is also one of the most sensitive growth stages to high temperature damage. During this stage, if sustained or intermittent high temperatures occur, pollen viability decreases, anther dehiscence is poor, stigma pollination and fertilization are hindered, and spikelets abort, leading to high-temperature-induced seedlessness, high-temperature-induced male sterility, and a decreased seed setting rate, ultimately affecting yield and yield stability. Especially in the middle and lower reaches of the Yangtze River and other major rice-producing areas, the heading and flowering stage often overlaps with seasonal periods of continuous high temperatures. If the entire field flowers simultaneously within the same high-temperature window, it often results in significant synchronous seed setting damage.

[0003] To address the problem of insufficient material supply during the grain-filling stage, existing technologies such as CN 112385496 B disclose a method for rice to avoid high temperatures and ensure yield. This method mainly relies on unified prediction of the growth period and treatment of key periods across the entire field to mitigate the disaster. However, due to the natural differences in the development process of different tillers, panicle positions, and nodes within the rice population in the field, and the suddenness and time window drift of high-temperature events, a mismatch easily occurs between the unified treatment measures and the actual time of damage, thereby affecting the high-temperature mitigation effect and yield stability.

[0004] As can be seen from the above, existing control measures mainly focus on how to temporarily resist high temperatures under concentrated flowering conditions in the whole field. The basic idea is still to ensure that most panicles complete flowering within the same flowering window, and then mitigate the impact of heat damage through external remedial measures. Therefore, there is an urgent need to provide a new method for cultivating rice to resist high temperatures, reduce the adverse effects of high temperature damage on the whole field and grain filling, reduce high temperature-induced tassel killing and grain failure, improve the grain filling rate, and take into account the uniformity of maturity and harvest suitability in the later stages. Summary of the Invention

[0005] The purpose of this invention is to provide a method for cultivating rice with high temperature resistance based on growth period regulation and integrated management, so as to solve the above-mentioned technical problems.

[0006] The high-temperature resistant rice cultivation method based on growth period regulation and integrated management proposed in this invention includes the following steps:

[0007] S1. During the greening to tillering period, by controlling the population density and coordinating with the timing of fertilization and irrigation in the early stage, establish a candidate group for the first peak fruiting of the main stem and low-position primary tillers, and a candidate group for the backup relay group for high-position primary tillers and early secondary tillers.

[0008] S2. In the middle and late stages of tillering, the tillers in the field are divided into groups according to the timing of tillering and growth status to obtain the first peak fruiting group, the reserve relay group, the middle group and the late group.

[0009] S3. At the end of tillering and before jointing, stop providing tillering-promoting fertilizer and water support to the intermediate group and the late-maturing group, and implement moist but not waterlogged control or removal treatment to make the field population converge into a double-peak flowering structure with the first peak fruiting group and the reserve relay group as the main components.

[0010] S4. After jointing and before heading, the peak flowering time difference between the first peak fruiting group and the reserve relay group is reviewed, and the peak flowering time difference is controlled to 5-7 days through subsequent fertilizer and water regulation.

[0011] S5. When the predicted or measured high temperature process overlaps with the heading and flowering window of the front peak grain-filling group or the backup relay group, maintain a shallow water layer in the field for 1 day before the start of the corresponding flowering peak to 2 days after the end, and supplement potassium during the heading period and foliar potassium supplementation for the corresponding flowering peak.

[0012] S6. After the flowering of the reserve relay group, implement maturity convergence management to reduce the maturity difference between the front-peak fruiting group and the reserve relay group, and harvest or quasi-harvest when the front-peak fruiting group and the reserve relay group meet the harvest conditions.

[0013] Furthermore, the grouping criteria include the tillering sequence and growth status, wherein the growth status includes at least one of leaf age difference, plant height, stem diameter, leaf color, and spikelet differentiation process.

[0014] Furthermore, tillers that sprout and grow vigorously 7–12 days after transplanting are classified as candidates for the first peak fruiting group; tillers that sprout and grow normally 17–22 days after transplanting are classified as candidates for the reserve relay group; tillers that sprout 13–16 days after transplanting are classified as candidates for the intermediate group; and tillers that sprout after 23 days after transplanting and are significantly weak are classified as candidates for the late-maturing group.

[0015] Furthermore, the population density is controlled at 11,000 to 14,000 planting holes per acre, with 2 to 3 seedlings per hole.

[0016] Furthermore, the moisture-free control includes: draining the surface water of the field to keep the field surface moist but not waterlogged for 2 to 3 days. The moist but not waterlogged state is that there is no continuous surface water on the field surface, the soil is kept moist and there is slight sinking when stepped on but no obvious cracks appear.

[0017] Furthermore, the high-temperature process meets any of the following conditions: the predicted maximum temperature in the next 1 to 3 days reaches 35°C or above, or the actual measured maximum temperature in the field reaches 35°C or above and shows a continuous upward trend.

[0018] Furthermore, the shallow water layer in step S5 is 3-5 cm deep, and when the expected maximum temperature of the day reaches 35°C or above, fresh water is added once before flowering in the morning.

[0019] Furthermore, the potassium supplementation during the heading stage is as follows: 60% to 70% of the total potassium application is used as basal application, and the remaining 30% to 40% is applied during the heading stage. The first supplementary application is carried out when the heading rate of the first grain-filling group reaches 15% to 20%, and the second supplementary application is carried out when the heading rate of the first grain-filling group reaches 75% to 85%.

[0020] Furthermore, the foliar potassium supplementation is carried out using a drone-based low-volume spraying method. The spraying solution is a potassium dihydrogen phosphate working solution with a mass fraction of 0.8% to 1.5%, and the spraying volume is 2 to 5 L per acre. Spraying is carried out 1 to 2 days after the beginning of heading in the first peak grain-bearing group and 1 to 2 days after the beginning of heading in the reserve relay group.

[0021] Furthermore, the mature harvesting management includes: maintaining a shallow water layer of 1-2 cm in the field for 2 days after the flowering of the reserve relay group, and then switching to moist irrigation; and carrying out unified harvesting or quasi-unified harvesting when the first peak fruiting group enters the late waxy ripening stage and the reserve relay group reaches the early yellow ripening stage.

[0022] The beneficial effects achieved by the present invention using the above structure are as follows:

[0023] (1) By constructing a bimodal flowering method with two groups before and after the flowering, the entire field of panicles no longer concentrates in the same flowering window to complete flowering and fruiting. This allows the continuous high temperature process during the heading and flowering period to be bypassed, disperse the adverse effects of high temperature on pollen viability, anther dehiscence and fertilization of spikelets, reduce high temperature killing of males and high temperature infertility, improve the fruit setting rate, and enhance the stable yield capacity in high temperature years.

[0024] (2) After the double-peak flowering is formed, the present invention further compresses the maturity misalignment between the two groups by controlling the truncation of the middle group and the late group and managing the maturity convergence of the later stage. This improves the seed setting rate while taking into account the uniformity of the later stage maturity and the feasibility of unified harvesting, thus avoiding the problem of excessive dispersion of maturity and harvesting difficulties caused by relying solely on staggered flowering. Attached Figure Description

[0025] Figure 1 This is a flowchart of the rice high-temperature resistant cultivation method based on growth period regulation and integrated management according to the present invention. Detailed Implementation

[0026] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0027] This invention provides a rice cultivation method for avoiding high temperatures based on the coordinated management of bimodal staggered flowering and heading stage heat resistance. Under single-sowing conditions, through population density control, fertilizer and water timing regulation during tillering, group determination, control of non-target tiller pruning, high-temperature resistance management during heading and flowering, and maturity convergence management, the main stem and early primary tillers form the leading peak grain-filling group, while late primary tillers and early secondary tillers form the backup relay group. The time difference between the flowering peak of the leading peak grain-filling group and the backup relay group is controlled within 5-7 days, thereby reducing the concentrated impact of a single high-temperature window during heading and flowering on synchronous flowering and grain filling across the entire field, mitigating pollen viability decline, spikelet fertilization obstacles, and high-temperature-induced infertility, improving the grain filling rate, and controlling the maturity misalignment within the range of uniform or near-uniform harvesting.

[0028] In this invention, the first-peak grain-filling group refers to the ear group that has a relatively early heading and flowering time in the population and is the main group responsible for the first round of grain filling; the backup relay group refers to the ear group that has a later heading and flowering time than the first-peak grain-filling group and is used to cross the high temperature window and compensate for grain filling; the intermediate group refers to the ear group whose heading time is between the first-peak grain-filling group and the backup relay group, which is likely to weaken the bi-peak boundary; and the late group refers to the ear group whose heading time is significantly delayed, which will widen the maturity misalignment and reduce the feasibility of unified harvesting.

[0029] In this invention, a combined determination method based on occurrence time and growth status is preferred for classifying panicle groups. Occurrence time is preferably based on the germination time window of each batch of tillers after transplanting, while growth status is preferably verified by combining leaf age difference, plant height, stem diameter, leaf color, and panicle differentiation process, thereby distinguishing the early-maturing group, the backup group, the intermediate group, and the late-maturing group.

[0030] Example 1:

[0031] This embodiment uses the indica rice variety "Y Liangyou 900" as the subject and is implemented in the double-cropping rice planting area of ​​the middle and lower reaches of the Yangtze River. The field used is a flat paddy field with good drainage and irrigation conditions. The soil type is loamy paddy soil with medium fertility in the topsoil. After the previous crop is harvested, rotary tillage is carried out and base fertilizer is applied in conjunction with the tillage.

[0032] This embodiment adopts a seedling transplanting method, with seedling age controlled at 25-30 days. At transplanting, 12,000-14,000 hills are planted per mu (approximately 667 square meters), with 2 seedlings per hill, establishing a population density lower than the local conventional uniform high-yield cultivation, thus reserving space for subsequent successor populations. Total nitrogen application is based on the appropriate level for local medium-to-high-yield fields, and is divided into four parts: basal application, application during the early tillering stage, peak-shaving application during the mid-tillering stage, and application during the young panicle differentiation stage. Preferably, basal nitrogen accounts for 35%-45% of the total nitrogen application, early tillering nitrogen accounts for 10%-20%, mid-tillering peak-shaving nitrogen accounts for 20%-30%, and young panicle differentiation nitrogen accounts for 15%-25%. Total potassium application, calculated as pure K2O, is 10 kg per mu, with 60% applied as basal fertilizer and 40% reserved for application during the heading and double-peak panicle stages.

[0033] During the greening and early tillering stage, maintain a shallow water layer of 1-2 cm in the field to ensure stable growth of the main stem and lower-positioned primary tillers. It is preferable to complete a light fertilization to promote tillering 7-10 days after transplanting, so that the main stem and lower-positioned primary tillers can form the initial peak base group first.

[0034] Thirteen to eighteen days after transplanting, when the low-level primary tillers have been basically established but the population has not yet entered the stage of disordered tillering, the first differential tillering regulation is implemented.

[0035] This stage begins by draining the surface water from the field, transforming it from a shallow water state to a moist but not waterlogged state, and maintaining this state for 2-3 days. The moist but not waterlogged state refers to a state where there is no continuous surface water, the soil remains moist, and there is slight sinking when stepped on but no obvious cracks appear.

[0036] The purpose of this stage is not to heavily control tillering, but to suppress the concentrated emergence of intermediate batches of tillers, thereby creating a time difference between the initial peak base group and the subsequent candidate later peak groups.

[0037] After completing the above-mentioned moist but not waterlogged stage, restore a shallow water layer of 1-2 cm, and apply a peak-shaving fertilizer during the mid-tillering stage within 24 hours after restoring the shallow water. The purpose of this fertilization is not to increase the total number of tillers, but to directionally maintain the continued growth of high-position primary tillers and early secondary tillers, so that they can form candidate ear groups for the reserve relay group.

[0038] During the mid-to-late tillering stage, fixed sample holes are selected for timing marking. At least 30 sample holes per acre are preferred, and the germination time of each batch of tillers is recorded. Tillers that germinate 7–12 days after transplanting and are vigorous are prioritized for the first-peak fruiting group; tillers that germinate 17–22 days after transplanting and have normal stem thickness, leaf color, and leaf age difference within a reasonable range are prioritized for the reserve relay group; tillers that germinate 13–16 days after transplanting and are expected to fall between the two peaks are prioritized for the intermediate group; tillers that germinate after 23 days after transplanting and are significantly weak are prioritized for the late-maturing group.

[0039] To avoid mistakenly retaining weak tillers as later peak groups, it is preferable to verify the results by combining plant height, stem diameter, functional leaf extension status, and pre-jointing spikelet differentiation examination.

[0040] From the late tillering stage to before jointing, the pruning control described in this embodiment is implemented. For tillers classified as intermediate or late-developing candidates, no further tillering-promoting fertilizer and water support is provided. The field surface is drained again to create a moist but not waterlogged state for 2-3 days to inhibit further tillering and ear formation. For significantly weak individuals that develop too late, manual removal can also be used to reduce their numbers. This pruning control causes the population to converge from a naturally multi-peaked expansion state to a bimodal structure dominated by a leading grain-filling group and a reserve relay group.

[0041] After jointing and before heading, the heading expectation of the field population is reviewed. The optimal method is to observe the development process of spikelets, the emergence process of flag leaves, and the difference in spike differentiation between the main stem and each batch of tillers in sample holes to determine the difference in flowering time between the two peaks.

[0042] If the predicted difference in peak flowering time between the preceding and following peaks is less than 5 days, the duration of subsequent shallow water retention should be appropriately shortened and all retention operations for the intermediate group should be stopped. If the predicted difference in peak flowering time between the preceding and following peaks is greater than 7 days, the intensity of subsequent water control should be reduced and the root zone of the candidate group for the following peak should be kept moist to avoid further delay in the following peak. In this embodiment, it is preferable to control the difference in peak flowering time between the preceding and following peaks to be between 5 and 6 days.

[0043] When the predicted maximum temperature for the next 1-3 days reaches 35℃, or the actual measured maximum temperature in the field has already reached 35℃ and shows a continuous upward trend, and the corresponding time period overlaps with the heading and flowering window of the preceding or subsequent seed-bearing group, it is determined that the field has entered a high-temperature sensitive state for heading and flowering. In this state, the management focus of this embodiment is not buffering the supply of ears during the grain-filling period, but rather reducing the adverse effects of high temperatures on flowering, pollination, and seed formation. Preferably, a shallow water layer of 3-5cm is maintained in the field from one day before the start of the corresponding flowering peak to two days after the end of the flowering peak; when the predicted maximum temperature for the day reaches 35℃ or above, fresh water is added once before flowering in the morning to reduce the heat load around the ear layer.

[0044] Regarding potassium management during the heading stage, this embodiment preferably recommends applying reserved potassium fertilizer twice during the initial heading to full heading stage to maintain a continuous potassium supply during the heading and flowering period, and to enhance anther dehiscence, pollen viability, and floret fertilization stability under high temperature conditions. The first application is preferably made when the initial heading rate of the first heading reaches 15%–20%, and the second application is preferably made when the full heading rate of the first heading reaches 75%–85%.

[0045] For foliar potassium supplementation, this embodiment uses a low-volume spraying method using drones instead of the conventional large-volume spraying method. It is preferable to spray once 1-2 days after the first heading and once 1-2 days after the second heading to cover the flowering window of the double-peak heading.

[0046] The preferred time for spraying is before 9:00 AM or after 4:00 PM, avoiding direct spraying during the peak blooming period of the flowers. For foliar potassium supplementation, potassium dihydrogen phosphate working solution with a mass fraction of 0.8%–1.5% is preferred, with a spray volume of 2–5 L per acre, ideally 3 L.

[0047] If necessary, adjuvants suitable for drone spraying can be added to improve adhesion and spreadability. The preferred spraying areas are the flag leaf, the second leaf from the top, the area near the neck of the panicle, and the outer surface of the upper leaf sheath. If it rains within 6 hours of spraying, re-spray the following day or after the leaves have dried following the rain.

[0048] After the flowering period of the second peak ends, to prevent the first peak from dehydrating too early while the second peak has not yet reached the appropriate harvesting state, this embodiment begins to implement maturity and convergence management. It is preferable to first maintain a shallow water layer of 1-2 cm on the field surface for 2 days, and then switch to moist irrigation, without adopting the method of premature water cut-off; between the early milk stage of the first peak and the early milk stage of the second peak, the soil is kept in a moist but not waterlogged state, so that the dehydration rate of the first peak is not too fast and the grain filling rate of the second peak is not too slow, thereby reducing the maturity difference between the two peaks.

[0049] Before harvesting, the risk of grain loss in the preceding peak and the maturity of the following peak are preferably used as the harvest trigger criteria. Ideally, uniform or semi-uniform machine harvesting should be carried out when the preceding peak reaches the late waxy ripening stage, the following peak reaches the early yellow ripening stage, and the difference in grain moisture content between the preceding and following peaks does not exceed a preset threshold. In this embodiment, the maturity misalignment between the preceding and following peaks can typically be controlled within 4 days.

[0050] Using the method of this embodiment, without relying on the single-peak concentrated flowering of the whole field, the front-peak fruiting group and the backup relay group can take on the task of dispersed fruiting across the target high temperature window. Through heat resistance management during the heading stage, the pollen abortion and unfruiting of spikelets induced by high temperature can be reduced. At the same time, the maturity difference can be converged to an acceptable uniform harvest range in the later stage, thus taking into account both the stable fruiting capacity under high temperature years and the adaptability of the later harvest.

[0051] Example 2:

[0052] This embodiment uses the japonica rice variety "Nanjing 46" as the subject and is implemented in a single-season rice planting area along the Yangtze River that is prone to high temperature and drought. The experimental plots are irrigation and drainage separate fields, the soil is clay loam with good water retention, and the plots are relatively flat, which is suitable for more precise fertilizer and water regulation and group management.

[0053] This embodiment is the same as Embodiment 1, both focusing on controlled bimodal staggered flowering and high-temperature resistance to fruit setting during the heading and flowering stages. However, this embodiment is an enhanced scheme, and its main differences are: the peak flowering time difference between the first and second peaks is controlled more favorably by 6 to 7 days; the reduction of the middle group and the late group is more explicit; and the high-temperature management during the flowering stage and the management of maturity convergence are further strengthened.

[0054] This embodiment adopts machine transplanting cultivation method, with 11,000 to 13,000 holes planted per mu, and 2 to 3 seedlings per hole. The total nitrogen application is controlled within the appropriate range based on pure N, of which basal nitrogen accounts for 35% to 40%, nitrogen application during the early tillering stage accounts for 10% to 15%, peak nitrogen application during the mid-tillering stage accounts for 25% to 30%, and nitrogen application during the young panicle differentiation stage accounts for 20% to 25%.

[0055] The total potassium application rate is 12 kg per mu (approximately 0.067 hectares) based on pure K2O, of which 60% is applied as basal fertilizer and 40% is reserved for supplementary application during the heading stage.

[0056] From the time the seedlings turn green until 8 days after transplanting, maintain a shallow water layer of about 1 cm to promote the stable formation of the main stem and lower-position primary tillers. 12-15 days after transplanting, begin the first tiller control and shaping process by draining the surface water and maintaining a moist but not waterlogged state for 2 days. After restoring the shallow water level, apply a mid-tillering fertilizer to support the formation of the expected high-position primary tillers and the early development of secondary tillers.

[0057] In this embodiment, a more stringent sample hole tracking method is used for cluster determination. Preferably, at least 50 sample holes per acre are used to record tillering occurrence, and clustering is performed jointly based on germination time, leaf age difference, and stem and tiller vigor.

[0058] For the intermediate group that is expected to fall between the two peaks, its continuous growth will no longer be maintained; for the obviously late-developing and weak late-growing group, all supportive fertilizer and water supply will be removed or stopped before jointing.

[0059] In this embodiment, a second pruning control is performed from the late tillering stage to before jointing. Compared with Example 1, the duration of the moist but not waterlogged stage in this embodiment tends to be 3 days to further reduce the possibility of the formation of a third and fourth peak. After completing the second pruning control, only the first peak grain-filling group and the reserve relay group are retained as the main ear-forming groups.

[0060] If, during the pre-heading review, the predicted difference in flowering time between the first and second peaks is less than 6 days, then all support for the intermediate population should be stopped and the shallow water maintenance time should be shortened.

[0061] If the predicted difference in flowering time between the first and second peaks exceeds 7 days, the second peak will not be further delayed by keeping the root zone moist and avoiding excessive water control. In this embodiment, the preferred time difference between the two peaks is controlled within 6 to 7 days.

[0062] When the predicted maximum temperature in the next 1 to 3 days reaches 36℃, or the actual measured maximum temperature in the field reaches 36℃ for 2 consecutive days and is accompanied by a significant increase in the heat load of the panicle layer in the afternoon, and this high temperature process overlaps with the heading and flowering period of the first or second peak, it is determined that the field has entered a state of high temperature sensitivity for intensified heading and flowering.

[0063] Unlike existing uniform populations, this embodiment uses a double-peak staggered arrangement to prevent the front and rear peaks from concentrating on flowering within the same high-temperature window;

[0064] Meanwhile, a shallow water layer of 3-5 cm should be maintained from one day before the start of the corresponding flowering peak to two days after its end, and fresh water should be added on the morning of the day with high temperature to further reduce the heat load on the ear layer and the risk of heat to the flower organs.

[0065] Regarding potassium management during the heading stage, this embodiment preferably recommends the first potassium supplementation when the initial heading rate reaches 15% to 20%, and the second potassium supplementation when the full heading rate reaches 75% to 85%, in order to ensure the continuity of potassium supply during the high-temperature window of the heading stage.

[0066] For foliar potassium supplementation, this embodiment also adopts the low-volume spraying method using drones. The first spraying is preferably scheduled one day after the beginning of the first heading peak, and the second spraying is preferably scheduled one to two days after the beginning of the second heading peak.

[0067] Foliar potassium supplementation is best achieved using potassium dihydrogen phosphate working solution with a mass fraction of 1.0%–1.5%. The spray volume per acre should be controlled at 2–5 L, preferably 3 L. If necessary, add an adjuvant suitable for drones to improve the adhesion rate of droplets to functional leaves and the neck of the panicle. When spraying, cover the flag leaf, the second leaf from the top, the area near the neck of the panicle, and the outer surface of the upper leaf sheath to continuously improve the stability of grain formation during the double-peak flowering stage.

[0068] During the maturity and convergence stage, this embodiment does not immediately switch to drying management after the flowering of the first peak ends, but first maintains shallow water for 2 days, and then switches to moist irrigation.

[0069] In the early stage of the later grain-filling stage, an additional foliar potassium application via drone can be applied based on the plant population status to promote grain filling in the later stage and the convergence of maturity between the earlier and later stages. This additional spraying is preferably carried out 4 to 6 days after the beginning of flowering in the later stage, with the spray volume still controlled at 2 to 5 L per acre, preferably 3 L.

[0070] Regarding harvest triggering, this embodiment preferably harvests uniformly when the grains of the current peak are not yet significantly shattered in the late waxy ripening stage, the subsequent peak has reached the early yellow ripening stage, and the difference in grain moisture content between the two peaks further converges.

[0071] Through the above-mentioned maturity convergence management, this embodiment can usually control the maturity misalignment between the first peak and the second peak within 3 days.

[0072] Using the method of this embodiment, under strong or sustained high temperature conditions, the high temperature risk can be more stably distributed to the two flowering peaks. By managing heat resistance during the double-peak heading stage, the seed setting rate can be improved and the high temperature-induced seed failure rate can be reduced. At the same time, the maturity difference can be effectively compressed in the later stage, thus maintaining good feasibility for uniform harvesting even in years with more severe heat damage.

[0073] Comparative Example 1:

[0074] This comparative example uses fields in the same ecological zone and with similar fertility levels as Example 1, with the indica rice variety "Y Liangyou 900" as the subject. The seedling raising method, transplanting time and total nutrient supply level are basically the same as in Example 1, but the local conventional uniform high-yield cultivation method is used for management to ensure that the basic conditions for comparison are basically the same.

[0075] The plant density in this comparative study was set according to local conventional methods, with approximately 16,000 planting holes per acre and 2-3 seedlings per hole. Nitrogen fertilizer was mainly applied at the beginning of the tillering stage, with a higher proportion of nitrogen applied in the early tillering stage. No targeted peak-shaving fertilization was carried out during the mid-tillering stage, and no management was implemented for the retention of reserve successor groups. In the field, no sampling holes were marked according to the time of tillering, and no distinction was made between the first-peak fruiting group, the reserve successor group, the middle group, and the late-maturing group. No tail-cutting control was implemented at the end of the tillering stage.

[0076] Regarding water management, this comparative study maintained the local conventional shallow water tillering method from greening to jointing, without creating a differential growth pattern through a moist but not waterlogged stage, nor managing the maturity difference through subsequent moist irrigation. Its population goal was to form a concentrated heading and flowering population as uniform as possible.

[0077] During the heading and flowering stage, this comparison example encountered high temperatures and only carried out water replenishment and layer protection or general heat resistance management in the conventional way. It did not disperse the high temperature risk by staggered flowering in two peaks, nor did it carry out corresponding management for the heading and flowering stages. Therefore, the main panicle groups in the field are more likely to be heated in the same high temperature window, resulting in decreased pollen viability, fertilization obstacles of spikelets, and increased high temperature-induced unfertilization rate.

[0078] During the ripening period, this comparative sample was allowed to ripen naturally with water cut off, without any convergence management based on the ripening differences between different batches of panicles.

[0079] This comparative example reflects the common practice of uniform single-peak flowering management in existing production. This approach improves the uniformity of operations by unifying the population, heading, and maturity, rather than by controlling the utilization of the difference between the main stem and tillers to mitigate the high-temperature risk during the heading and flowering period and to ensure harvestability in the later stages.

[0080] Effect comparison explanation:

[0081] Field observations were conducted under similar variety types, similar basic fertility conditions, and similar sowing and planting periods. The seed setting rate of both Example 1 and Example 2 was better than that of Comparative Example 1 under high temperature conditions during the heading and flowering period. Furthermore, the improvement of Example 2 was generally greater than that of Example 1 under continuous high temperature or longer high temperature duration conditions.

[0082] In Example 1, compared to Comparative Example 1, the peak flowering time difference between the first and second peaks can usually be controlled within 5 to 6 days. The main panicle groups in the field are no longer concentrated in a single high-temperature flowering window, the seed setting rate can usually be increased by about 2 to 4 percentage points, the high-temperature unfilling rate is relatively low, the thousand-grain weight and subsequent maturity uniformity are well maintained, and the maturity difference between the first and second peaks can usually be controlled within 4 days, which has good feasibility for unified harvesting.

[0083] Compared to Comparative Example 1, Example 2 shows that the peak flowering time difference between the first and second peaks can usually be controlled within 6 to 7 days, the risk-sharing effect of the two peaks is more obvious, the fruit setting rate can usually be increased by about 3 to 5 percentage points, the high-temperature unfruiting rate is reduced more significantly, and by strengthening the management of pruning and maturity convergence, the maturity misalignment between the first and second peaks can usually be controlled within 3 days. In years with longer high-temperature duration or more severe heat damage, its advantages are more obvious.

[0084] In comparison, due to the adoption of a uniform single-peak flowering method, the main spikelet groups were more likely to be damaged simultaneously within the same high-temperature window.

[0085] At the same time, it did not truncate the middle group and the late group, nor did it converge the maturity difference in the later stage. Therefore, once the high temperature impacts the main flowering window, the loss of grain filling in the whole field is more likely to be concentrated and amplified, and the maturity end is either damaged as a whole or the uniformity is reduced at harvest.

[0086] The above comparative results show that in areas with high temperature risk during heading and flowering, a combination of measures, including population density control, timing regulation of fertilizer and water during tillering, group identification, pruning of non-target populations, heat resistance management during the bimodal heading stage, and maturity convergence management, can create a controlled bimodal flowering structure in the field. This reduces the risk of unfilled seeds due to high temperature during the flowering stages corresponding to the first and second peaks, while compressing the maturity misalignment to a harvestable range. Thus, under single-sowing conditions, it simultaneously achieves high temperature risk dispersion, increased seed setting rate, and adaptation to later harvest.

[0087] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention. The actual method is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar methods and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A method for cultivating rice to withstand high temperatures based on growth period regulation and integrated management, characterized in that, Includes the following steps: S1. During the greening to tillering period, by controlling the population density and coordinating with the timing of fertilization and irrigation in the early stage, establish a candidate group for the first peak fruiting of the main stem and low-position primary tillers, and a candidate group for the backup relay group for high-position primary tillers and early secondary tillers. S2. In the middle and late stages of tillering, the tillers in the field are divided into groups according to the timing of tillering and growth status to obtain the first peak fruiting group, the reserve relay group, the middle group and the late group. S3. At the end of tillering and before jointing, stop providing tillering-promoting fertilizer and water support to the intermediate group and the late-maturing group, and implement moist but not waterlogged control or removal treatment to make the field population converge into a double-peak flowering structure with the first peak fruiting group and the reserve relay group as the main components. S4. After jointing and before heading, the peak flowering time difference between the first peak fruiting group and the reserve relay group is reviewed, and the peak flowering time difference is controlled to 5-7 days through subsequent fertilizer and water regulation. S5. When the predicted or measured high temperature process overlaps with the heading and flowering window of the front peak grain-filling group or the backup relay group, maintain a shallow water layer in the field for 1 day before the start of the corresponding flowering peak to 2 days after the end, and supplement potassium during the heading period and foliar potassium supplementation for the corresponding flowering peak. S6. After the flowering of the reserve relay group, implement maturity convergence management to reduce the maturity difference between the front-peak fruiting group and the reserve relay group, and harvest or quasi-harvest when the front-peak fruiting group and the reserve relay group meet the harvest conditions.

2. The method for cultivating rice to withstand high temperatures according to claim 1, characterized in that, The grouping criteria include the tillering sequence and growth status, and the growth status includes at least one of leaf age difference, plant height, stem diameter, leaf color, and young spikelet differentiation process.

3. The method for cultivating rice to withstand high temperatures according to claim 2, characterized in that, Tillers that sprout and grow vigorously 7–12 days after transplanting are designated as candidates for the leading fruiting group; tillers that sprout and grow normally 17–22 days after transplanting are designated as candidates for the reserve relay group; tillers that sprout 13–16 days after transplanting are designated as candidates for the intermediate group; and tillers that sprout after 23 days after transplanting and are significantly weak are designated as candidates for the late-maturing group.

4. The method for cultivating rice to withstand high temperatures according to claim 1, characterized in that, The population density is controlled at 11,000 to 14,000 planting holes per acre, with 2 to 3 seedlings per hole.

5. The method for cultivating rice to withstand high temperatures according to claim 4, characterized in that, The control of moisture without water accumulation includes: draining the surface water of the field to keep the field surface moist but not waterlogged for 2 to 3 days. The state of being moist but not waterlogged means that there is no continuous surface water on the field surface, the soil is kept moist and there is slight sinking when stepped on but no obvious cracks appear.

6. The method for cultivating rice to withstand high temperatures according to claim 1, characterized in that, The high-temperature process meets any of the following conditions: the predicted maximum temperature in the next 1 to 3 days reaches 35°C or above, or the actual measured maximum temperature in the field reaches 35°C or above and shows a continuous upward trend.

7. The method for cultivating rice to withstand high temperatures according to claim 6, characterized in that, In step S5, the shallow water layer is 3-5 cm deep, and when the expected maximum temperature of the day reaches 35°C or above, fresh water is added once before flowering in the morning.

8. The method for cultivating rice to withstand high temperatures according to claim 1, characterized in that, The potassium supplementation during the heading stage is as follows: 60% to 70% of the total potassium application is applied as basal application, and the remaining 30% to 40% is applied during the heading stage. The first supplementation is carried out when the heading rate of the first grain-filling group reaches 15% to 20%, and the second supplementation is carried out when the heading rate of the first grain-filling group reaches 75% to 85%.

9. The method for cultivating rice to withstand high temperatures according to claim 8, characterized in that, Foliar potassium supplementation is carried out using a drone for low-volume spraying. The spray solution is potassium dihydrogen phosphate working solution with a mass fraction of 0.8% to 1.5%. The spray volume is 2 to 5 L per acre. Spraying is carried out 1 to 2 days after the beginning of heading in the first fruiting group and 1 to 2 days after the beginning of heading in the reserve relay group.

10. The method for cultivating rice to withstand high temperatures according to claim 1, characterized in that, The mature harvesting management includes: maintaining a shallow water layer of 1-2 cm in the field for 2 days after the flowering of the reserve relay group, and then switching to moist irrigation; and carrying out unified harvesting or quasi-unified harvesting when the first peak fruiting group enters the late waxy ripening stage and the reserve relay group reaches the early yellow ripening stage.

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