Nitrogen regulation and control method for shortening growth period of rice

Abstract

The invention belongs to the technical field of agriculture, and particularly relates to a nitrogen regulation and control method for shortening the growth period of rice. According to the test, the regulation and control effect of short-term nitrogen concentration dynamic change (not the constant nitrogen level in the traditional research) on the flowering time of the rice is explored, and the special treatment mode of changing the nitrogen concentration from high to low (HTL) in the booting stage can more effectively promote the rice to bloom in advance (3 days shortened) compared with constant high nitrogen or constant low nitrogen) and keep the high yield. The nitrogen regulation and control method for shortening the growth period of the rice comprises the following steps that first-stage nitrogen treatment is provided at the front stage of the booting stage of the rice, second-stage nitrogen treatment is provided at the rear stage of the booting stage of the rice, in the booting stage of the rice, stem end growth cones are differentiated to flag leaf pillows to expose tips, and during the first-stage nitrogen treatment, the second-stage nitrogen treatment is carried out; the usage amount of the nitrogen fertilizer is 0.5-1 mM; during the second-stage nitrogen treatment, the usage amount of the nitrogen fertilizer is 6-8 mM.

Description

Technical Field

[0001] This invention belongs to the field of agricultural technology, and in particular relates to a method for nitrogen regulation that shortens the growth period of rice. Background Technology

[0002] Rice ( Oryza sativa L. Rice (Poaceae) is an annual aquatic herbaceous plant that thrives in hot and humid climates and is widely distributed in subtropical regions. Nitrogen fertilizer is a key factor determining rice yield, and the choice of application conditions has a decisive impact on rice growth and development, especially the regulation of reproductive growth. Sufficient nitrogen supply is fundamental to ensuring effective tillering, establishing a reasonable plant population structure, and promoting photosynthesis, directly affecting the final number of panicles, grains, and grain weight. However, improper timing of nitrogen fertilizer application not only leads to nutrient loss and environmental burden but also seriously disrupts the internal physiological balance of rice, particularly negatively impacting reproductive growth during critical growth stages.

[0003] Currently, improvements in nitrogen fertilizer management technology mainly focus on two directions. On the one hand, optimizing fertilizer form and release patterns. For example, patent CN106171222A employs the SPAD relative value diagnostic method, which, by combining slow-release fertilizers with leaf color digitization technology, improves the stability of nitrogen supply. On the other hand, developing precision fertilization technologies, such as drone-based variable-rate fertilization and real-time soil-plant nutrient monitoring. While these technologies have made some progress in spatial dimensions (positioned fertilization) and total quantity dimensions (on-demand adjustment), they generally lack sufficient attention to the refined control of nitrogen concentration changes in the temporal dimension.

[0004] Taking patent CN106171222A as an example, it only matches a fixed nitrogen application ratio (5%~25%) based on discrete thresholds (such as ≤1, 1~1.1, ≥1.1) of the relative value of SPAD during four preset growth stages. This "static threshold + step-by-step fertilization" model has many defects. At the beginning of panicle differentiation, a single fertilization node cannot distinguish between the two opposite needs: the branch differentiation period (which requires a rapid increase in nitrogen concentration within 48 hours) and the spikelet degeneration period (which requires reduced nitrogen regulation). At the beginning of heading, it only uses 1.05 as the boundary to determine whether to apply 5% granular fertilizer, completely ignoring the need to actively reduce nitrogen concentration in the early grain-filling stage to prevent assimilate transport obstruction. Furthermore, its decision-making relies on delayed leaf color feedback (for example, as recorded in CN106171222A, "the top 4 leaves of rice are older leaves in the canopy and are less sensitive to nitrogen. When nitrogen deficiency occurs in these leaves, fertilization is often delayed, affecting the fertilization effect"), making it impossible to adjust the nitrogen concentration in advance 24 hours before the critical point of panicle differentiation in order to seize the development window.

[0005] The above problems reflect the inherent defects of the prior art, i.e., excessive reliance on empirical reproductive period division, which breaks the dynamic correlation between nitrogen concentration regulation and reproductive development physiological signals. Although the patent CN106171222A eliminates the interference of variety differences through relative value diagnosis, the fertilization time and concentration still deviate from the internal development rhythm of rice. For example, when high temperature stress causes branch differentiation to advance to leaf age remainder 4.0, the prior art still mechanically waits until the leaf age remainder 3.5 to detect the SPAD value, thereby missing the optimal nitrogen increase window; similarly, under the environment of rain and shade, the meiosis is delayed, but the fertilization fertilizer is still applied at the preset leaf age remainder 1.5 with a fixed proportion, resulting in the misalignment of the nitrogen concentration peak and the fertility sensitive period.

[0006] This "concentration-time decoupling" regulation mode is the essential reason for the fluctuation of spike grain number, the decrease of seed setting rate and the difficulty of breaking through the yield potential. Therefore, it is urgent to develop a fertilization timing control technology that can integrate the physiological signals of key turning points of rice reproductive growth and dynamically adapt the nitrogen concentration change curve, in order to solve the dual deficiencies of the existing methods in time node sensitivity and concentration gradient continuity. SUMMARY

[0007] In order to overcome the deficiencies of the prior art, the present test explores the regulation effect of short-term nitrogen concentration dynamic change (rather than the traditional constant nitrogen level) on the flowering time of rice, and reveals that the special treatment method of changing the nitrogen concentration from high to low (HTL) at the booting stage can more effectively promote the early flowering of rice (shorten by 3 days) and maintain high yield than constant high nitrogen or constant low nitrogen, which provides a new idea for shortening the breeding cycle of rice in plant factory environment through dynamic regulation of nitrogen.

[0008] One of the purposes of the present application is to provide a nitrogen regulation method for shortening the growth period of rice, which comprises the following steps: providing a first stage nitrogen treatment when the number of tillers of rice is less than 14, and providing a second stage nitrogen treatment when the number of tillers of rice is not less than 14, wherein, In the first stage nitrogen treatment, the amount of nitrogen fertilizer used is 0.5-1 mM; In the second stage nitrogen treatment, the amount of nitrogen fertilizer used is 6-8 mM.

[0009] Preferably, in the first stage nitrogen treatment, the amount of nitrogen fertilizer used is 0.54 mM. In the second stage nitrogen treatment, the amount of nitrogen fertilizer used is 6.48 mM.

[0010] According to a preferred embodiment, 1.65 mM CaCl2 is supplemented in the first stage nitrogen treatment.

[0011] According to a preferred embodiment, the rice is cultivated using Kimura B nutrient solution.

[0012] According to a preferred embodiment, during the first stage of nitrogen treatment, the (NH4)2SO4 and Ca(NO3)2·4H2O in the Kimura B nutrient are adjusted to 0.12 mM (NH4)2SO4 and 0.06 mM Ca(NO3)2·4H2O, respectively; during the second stage of nitrogen treatment, the (NH4)2SO4 and Ca(NO3)2·4H2O in the Kimura B nutrient are adjusted to 1.44 mM (NH4)2SO4 and 1.71 mM Ca(NO3)2·4H2O.

[0013] According to a preferred embodiment, the molar concentration ratio of ammonium nitrogen to nitrate nitrogen is 4:5.

[0014] According to a preferred embodiment, a light source with an intensity of 300 µmol·m⁻²·s⁻¹ is supplemented during both the first and second stages of nitrogen treatment. Preferably, the light intensity ratio is blue light: green light: red light: infrared light = 3:3:3:1. The photoperiod is 11 h day / 13 h night. The relative humidity is 60%.

[0015] According to a preferred embodiment, the nutrient solution comprises: 0.36 mM (NH4)2SO4, 0.18 mM KH2PO4, 0.18 mM KNO3, 0.09 mM K2SO4, 0.36 mM Ca(NO3)2·4H2O, 0.54 mM MgSO4·7H2O, 0.8 mM Na2SiO3, 0.02 mM FeSO4-NaEDTA, 0.9 µM MnCl2·4H2O, 0.046 mM H3BO3, 0.5 µM H2MoO4, 0.8 µM ZnSO4·7H2O, and 0.3 µM CuSO4·5H2O.

[0016] According to a preferred embodiment, the light source is a light source that sends light to the plant canopy.

[0017] One of the objectives of this invention is to provide a method for shortening the growth period of rice, wherein the method is to shorten the growth period of rice by using the above-mentioned nitrogen regulation method.

[0018] One of the objectives of this invention is to provide the use of the nitrogen regulation method described above for accelerating the development speed of rice anthers, accelerating the flowering time of rice, and improving the carbon metabolism of rice.

[0019] The beneficial effects of this technical solution are: This invention establishes a method for dynamically regulating nitrogen application based on tiller number, focusing on the regulatory effect of short-term dynamic changes in nitrogen concentration (rather than the traditional constant nitrogen level) on rice flowering time. Experimental results demonstrate that a special treatment of transitioning from high to low nitrogen concentration (HTL) during the booting stage is more effective than constant high or constant low nitrogen treatment in advancing rice flowering by 3 days and maintaining high yield. This discovery provides a new approach for shortening the rice breeding cycle through dynamic nitrogen regulation in a plant factory environment.

[0020] Based on the synergistic study of carbon and nitrogen metabolism, this invention discovers that dynamically adjusting exogenous nitrogen can achieve a linked regulatory effect on nitrogen and carbon metabolism (especially carbon fixation capacity) in plants. Based on this regulatory mechanism, this invention identifies the optimal timing and conditions for nitrogen regulation, achieving high yield and improved plant structure while aiming to improve yield and plant type.

[0021] Furthermore, given the relatively limited current research on the regulation of flowering time by crop carbon and nitrogen metabolism, this study comprehensively measured the photosynthetic characteristics of rice leaves, the activities of key carbon and nitrogen metabolism enzymes (such as Rubisco, SPS, NR, and GS) and their assimilation products, and combined them with yield components to deeply analyze the physiological and biochemical mechanisms by which nitrogen affects rice carbon and nitrogen metabolism and thus regulates flowering. This provides important theoretical reference value for understanding the relationship between plant flowering and carbon and nitrogen metabolism. Attached Figure Description

[0022] Figure 1 Phenotypic diagrams of the four treatment groups during the booting stage; Figure 2 Flowering status of rice in different treatments at the same time point; Figure 3 The number of rice flowers over time was statistically analyzed under each nitrogen-changing treatment. Figure 4 The effects of different nitrogen treatments on total leaf area and tiller number in rice; Figure 5 The width and length of rice grains under different nitrogen application methods; Figure 6 The starch content, soluble sugar content, sucrose content, and SPS activity of rice leaves under different nitrogen treatments were measured. Figure 7 This figure shows the expression analysis of differentially expressed genes related to carbon and nitrogen metabolism in rice by qRT-PCR. In the figure, lowercase letters indicate significant differences (p<0.05) in the same treatment at different time points. The left Y-axis represents the relative expression level of qRT-PCR, and the right Y-axis represents the FPKM value of RNA-seq. Detailed Implementation

[0023] In the description of this invention, terminology is used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly defined.

[0024] All raw materials used in the following examples are commercially available or self-made; unless otherwise specified, their mass percentage content is indicated.

[0025] This invention systematically investigated the effects of short-term nitrogen concentration changes on rice flowering time, growth and development, photosynthesis, carbon and nitrogen metabolism, and yield formation. It also explored the physiological mechanisms by which short-term nitrogen concentration changes regulate rice flowering from the perspectives of photosynthesis and carbon and nitrogen metabolism. Experimental results showed that short-term nitrogen concentration changes during the booting stage (especially when rice enters the 14-tillering stage) effectively stimulated changes in the activity of nitrogen metabolism-related enzymes such as NR, GS, and GAGOT, affecting nitrogen absorption. This controlled the synthesis of Rubisco, a key enzyme required for plant photosynthesis, and chlorophyll, significantly influencing the synthesis, transport, and distribution of carbohydrates, especially sucrose, thus regulating flowering time, yield, and quality.

[0026] Statistical data from different treatments show that the HTL treatment group, while shortening the rice flowering cycle, also retained the characteristics of high yield and high quality. This makes it the optimal treatment scheme for rapid rice propagation in a plant factory environment, applicable to this experiment. These results provide important theoretical basis for the efficient cultivation and breeding of rice. Future research should further explore the interaction effects of nitrogen with other nutrients, as well as the molecular-level mechanisms for efficient nitrogen utilization, to provide technical support for green, high-yield, and high-quality rice cultivation.

[0027] The following experimental materials and cultivation environment The rice variety tested was the indica rice variety 'CP511'. Oryza sativa L. This variety, provided by Academician Qian Qian's team at the China National Rice Research Institute, is characterized by its short plant height and short growth period, typically around 60 days from transplanting to flowering under normal conditions. It was cultivated using hydroponics in an artificial climate chamber. Plump, clean rice seeds were selected, disinfected, and germinated before being sown in 10×20 cm seed boxes with 96 cells. Seedlings were nurtured for two weeks using a 1 / 2 concentration Kimura B nutrient solution. Healthy seedlings with uniform growth were then selected and transplanted onto hydroponic cultivation racks in the artificial climate chamber.

[0028] Example 1 This embodiment divides rice into four treatment groups by applying different nitrogen application rates at different growth stages: LN treatment group (low nitrogen treatment throughout the growth period), HN treatment group (high nitrogen treatment throughout the growth period), LTH treatment group (low nitrogen treatment before booting stage and high nitrogen treatment after booting stage), and HTL treatment group (high nitrogen treatment before booting stage and low nitrogen treatment after booting stage). Each treatment has 60 plants, and there are three replicates.

[0029] The point at which rice seedlings reached 14 tillers (45 days after transplanting [early booting stage] in this experiment) was used as the cutoff point for changing nitrogen concentration. Nitrogen content was controlled by supplementing with 1.65 mM CaCl2 and adjusting the concentrations of (NH4)2SO4 and Ca(NO3)2·4H2O in Kimura B nutrient solution (LN: 0.12 mM (NH4)2SO4, 0.06 mM Ca(NO3)2·4H2O; HN: 1.44 mM (NH4)2SO4, 1.71 mM Ca(NO3)2·4H2O) while maintaining a constant ammonium nitrogen to nitrate nitrogen ratio of 4:5. The concentrations of other trace elements, such as Ca, were also kept consistent. The low nitrogen concentration was 0.54 mM, and the high nitrogen concentration was 6.48 mM. The LN treatment group received a continuous low nitrogen treatment of 0.54 mM, and the HN treatment group received a continuous high nitrogen treatment of 6.48 mM. The LTH treatment group received a low nitrogen treatment of 0.54 mM before the rice seedlings reached 14 tillers; after reaching 14 tillers, they received a high nitrogen treatment of 6.48 mM. The HTL treatment group received a high nitrogen treatment of 6.48 mM before the rice seedlings reached 14 tillers; after reaching 14 tillers, they received a low nitrogen treatment of 0.54 mM.

[0030] During the experiment, the nutrient solution (Kimura B nutrient solution) was changed every 15 days. An LED light panel was used as the light source, and the light intensity received by the plant canopy was 300 µmol·m⁻²·s⁻¹. The spectrum is as follows: Figure 1 As shown, the light intensity ratio is blue light: green light: red light: infrared light = 3:3:3:1, the photoperiod is 11 h day / 13 h night, the relative humidity is 60%, and the day / night temperature is 28±1℃ / 22±1℃.

[0031] Forty-five days after transplanting, ten uniformly growing plants were selected from each treatment. The number of tillers and plant height were monitored every three days, with the absolute plant height from stem base to leaf tip measured using a ruler. Additionally, five plants were destructively sampled every three days for a total of five times to measure leaf area and dry weight of roots, stems, and leaves. The heading and flowering times of rice in each treatment were recorded daily until all plants had headed and flowered. Later, specific leaf weight (SLW) and other indicators were calculated.

[0032] After the rice in each treatment group reached grain filling and maturity, a 1m sample was taken from the same location in each planting area under different treatments. 2 The total number of panicles and the number of effective panicles in rice are measured. After removing impurities and drying, the weight of the grains is weighed, and finally the indicators such as the weight of 100 grains, the grain filling rate and the final yield are calculated.

[0033] In addition, a portable photosynthesis meter was used to measure the photosynthetic parameters of the first fully expanded functional leaf from the top down in rice at each sampling period of each treatment. Five constant replicate plants were selected for each measurement, for a total of five measurements. During the measurements, the environmental parameters of the leaf chamber were set as follows: temperature 28℃, CO2 concentration 400 µmol / mol (except during the measurement of the CO2 response curve), relative humidity 65%, and air velocity 500 µmol / s. The light source in the leaf chamber was provided by red and blue light (10% blue light, 90% red light).

[0034] (a) Results of growth phenotype detection like Figure 2 The image shown is a photograph of the flowering status taken on the 9th day after the nitrogen concentration was changed. The results show that LTH and HTL treatments resulted in earlier opening of the spikelets. The standard for entering the flowering stage was defined as 50% of the plants being in bloom. Figure 3 The statistical results of flowering plant counts under different treatments showed that the LTH and HTL treatment groups entered the flowering period 3 days earlier than the LN and HN treatment groups, and 50% of the plants were in bloom 3 days earlier.

[0035] like Figure 4 As shown in Table A and Table 1, after changing the nitrogen concentration 45 days after rice transplanting, the total leaf area of ​​all treatment groups showed an increasing trend over the following 12 days. The leaf area of ​​the HN group was significantly higher than that of the LN treatment throughout the period. The HN group showed a higher leaf area initially, gradually increasing over time, eventually reaching 1282.37 cm². In contrast, the LN group's leaf area remained at a lower level, peaking at only 610.84 cm². Furthermore, the LTH group's leaf area increased rapidly within 3 days after the increase in nitrogen supply, leveled off between days 3 and 9, and then increased rapidly after day 9, eventually reaching 783.80 cm², a 28.31% increase compared to the LN group. In contrast, the HTL group's leaf area began to decrease after day 6 after the reduction in nitrogen supply, showing a significant difference by day 9, and decreased by 13.65% after 12 days.

[0036] like Figure 4B and the tillering statistics shown in Table 1 indicate that after the nitrogen concentration changed 45 days after rice transplanting, the tillering number increased in all treatments. On day 0, the tillering numbers in the HN and HTL groups were significantly higher than those in the LN and LTH groups, but the difference was not significant. There was no significant difference in tillering numbers among the LN, HN, and HTL groups from day 3 to day 12, ultimately reaching 20.50, 20.25, and 19.50 tillers respectively, representing increases of 36.67%, 17.39%, and 11.43% over 12 days. Compared to the LN group, the LTH treatment group showed a significant increase in tillering numbers in the first 3 days after the nitrogen concentration increase, which leveled off from day 3 to day 6, but began to rise rapidly and significantly after day 6, ultimately reaching as high as 28.25 tillers, an increase of 106.78% over 12 days. In summary, a decrease in nitrogen concentration has no significant effect on the number of rice tillers, while an increase in nitrogen concentration can increase rice tillering in the short term and continue to increase rapidly after the 6th day.

[0037] Table 1 .

[0038] (ii) Carbon metabolism (1) Starch content Figure 6 The results show the dynamic statistics of starch content in rice leaves of each group over 12 days after nitrogen concentration changes. The results indicate that the starch content in the LN group was significantly higher than that in the HN group throughout the 12 days, and both groups maintained a relatively stable level. Compared to the LN group, the LTH treatment group showed a rapid and significant decrease in starch content to a level comparable to the HN group within 6 days after nitrogen supply was increased, and maintained no significant difference from the HN treatment for the next 6 days, ultimately showing a significant decrease of 42.18% compared to the LN group. In contrast, the HTL treatment group showed no significant change in starch content for the first 3 days after nitrogen supply was reduced, until it began to increase significantly on the 6th day, ultimately showing a significant increase of 68.47% compared to the HN group, but still significantly lower than the starch content level of the LN group.

[0039] (2) Soluble sugar content Figure 6The results show the statistical analysis of soluble sugar content in rice leaves of each group over 12 days after nitrogen concentration changes. The results indicate that the soluble sugar content in the LN group was significantly higher than that in the HN group, and remained relatively constant over time. Compared to the LN group, the soluble sugar content in the LTH treatment group decreased rapidly and significantly after nitrogen supply increased, reaching a level with no significant difference from the HN group after day 6, ultimately showing a significant decrease of 35.34% compared to the LN group. Conversely, the soluble sugar content in the HTL treatment group showed an increasing trend after nitrogen supply decreased, showing a significant difference from the HN group starting on day 6, and increasing to 131.14 mg / g by day 12, comparable to the soluble sugar content level of the LN group, ultimately showing an increase of 71.26% compared to the HN group. It is evident that the starch content and soluble sugar content in rice leaves exhibit similar responses to changes in nitrogen concentration. Both are more sensitive to increases in nitrogen concentration and can produce rapid changes, while their response to decreases in nitrogen concentration is relatively sluggish, often showing significant changes only after 6 days.

[0040] (3) Sucrose content Sucrose is the main form of carbohydrate transport in plants, and its content changes have an important impact on the distribution of nutrients. Figure 6 Data showed that the sucrose content in rice leaves exhibited significant dynamic changes within 12 days following changes in nitrogen concentration. The LN group maintained a low sucrose content throughout the experiment, while the HN treatment group showed significantly higher sucrose content than the LN group, consistently maintaining a higher level. Unlike the LN and HN groups, the LTH treatment group showed no significant difference in sucrose content compared to the LN group for the first 6 days after the increase in nitrogen supply, only showing a significant increase on the 9th day, and reaching a level comparable to the HN treatment after 12 days, representing a significant increase of 112.13%. In contrast, the HTL treatment group showed a significant decrease in sucrose content in plant leaves starting on the 6th day, and reaching a level comparable to the LN treatment group after 12 days, representing a significant decrease of 60.85%. The changes in sucrose content showed an opposite trend to those of starch, soluble sugar content, and SPS activity. This may be because while increased SPS activity under decreased nitrogen concentration promoted sucrose synthesis, the roots required more nutrients to promote root growth in order to cope with the nitrogen-deficient environment. As a result, the rate of sucrose output from the leaves was greater than the rate of synthesis, thus causing the difference in sucrose content in the leaves.

[0041] (4) Sucrose phosphate synthase (SPS) activity SPS is a key enzyme that regulates sucrose synthesis and is closely related to changes in sucrose content. Figure 6The results show the dynamic statistical effects of SPS activity in rice leaves over 12 days following changes in nitrogen concentration. In the LN group, SPS activity in plant leaves remained relatively stable at a high level throughout the experiment with minimal fluctuations. In contrast, SPS activity in the HN treatment group was significantly lower than that in the LN treatment group and remained at a low level throughout. Compared to the LN group, SPS activity in the LTH treatment group decreased significantly on day 3, and by day 12, it had decreased by 46.54% compared to the LN group. Conversely, SPS activity in the HTL treatment group showed no significant change in the first 6 days, a significant difference appeared on day 9, and by day 12, it had increased significantly by 77.22% compared to the HN group.

[0042] (III) Output As shown in Table 2, the aboveground dry weight of the LN treatment was significantly lower than that of the HN treatment, while the underground dry weight of the LN group was significantly higher than that of the HN treatment. Compared with the LN treatment, the aboveground dry weight of the LTH treatment group showed no significant change, while the underground dry weight decreased significantly by 26.23%; compared with the HN treatment, the aboveground dry weight of the HTL treatment showed no significant difference, while the underground dry weight decreased significantly by 19.57%.

[0043] Under different nitrogen application treatments, the LTH treatment resulted in an average of 30.5 tillers per rice plant, significantly higher than the other three treatments, while there was no significant difference in tiller number among the LN, HN, and HTL treatments. Furthermore, the leaf area under the LN treatment was only 610.84 cm², significantly lower than the 1282.37 cm² under the HN treatment. Compared to the LN treatment, the LTH treatment significantly increased the leaf area by 28.32%; compared to the HN treatment, the HTL treatment significantly decreased the leaf area by 13.65%. Similar results were observed in specific leaf weight among the treatment groups: the LTH treatment significantly increased the specific leaf weight compared to the LN treatment, while the HTL treatment significantly decreased the specific leaf weight compared to the HN treatment.

[0044] Table 3 shows the rice yield under different treatments. It can be seen that, compared to the continuous high nitrogen treatment (394.77 g / m³), the yield of rice significantly decreased. 2 Low nitrogen treatment (179.64 g / m³) 2 ) and low-nitrogen followed by high-nitrogen treatment (200.81 g / m³) 2 The cultivation method described in this invention can significantly increase rice yield (435.51 g / m³). 2 ).

[0045] Table 2

[0046] Table 3

[0047] Based on the above research results, it can be seen that the dynamic adjustment of nitrogen has a significant positive feedback effect on plant carbon metabolism and the resulting yield and phenotype.

[0048] (iv) Genetic influence In this study, samples collected on days 0, 3, 6, 9, and 12 after nitrogen concentration changes for four treatments (LN, HN, HTL, and LTH) were subjected to high-throughput sequencing. LN1, LN2, LN3, LN4, and LN5 represent the five sampling time points for the LN treatment, and the other three treatments were similar. A total of 20 samples were collected, with each sample containing three biological replicates.

[0049] like Figure 7 As shown, OsTPI1.1 , OsCYN , OsBGLU5 These three genes all showed a significant upward trend under LTH treatment, reaching their peaks on days 6, 6, and 9, respectively; while OsFd-GOGAT , OsSPS1 Both genes showed a significant decreasing trend after nitrogen concentration increased, and both reached their lowest values ​​on day 6.

Claims

1. A nitrogen regulation method, characterized in that, The method includes the following steps: providing a first-stage nitrogen treatment when the number of rice tillers is less than 14, and providing a second-stage nitrogen treatment when the number of rice tillers is not less than 14, wherein, During the first stage of nitrogen treatment, the amount of nitrogen fertilizer used is 0.5~1 mM; During the second stage of nitrogen treatment, the amount of nitrogen fertilizer used is 6-8 mM.

2. The nitrogen regulation method according to claim 1, characterized in that, During the first stage of nitrogen treatment, 1.65 mM CaCl2 was added.

3. The nitrogen regulation method according to claim 1, characterized in that, Kimura B nutrient solution was used to cultivate rice.

4. The nitrogen regulation method according to claim 3, characterized in that, During the first stage of nitrogen treatment, the concentrations of (NH4)2SO4 and Ca(NO3)2·4H2O in Kimura B nutrient were adjusted to 0.12 mM (NH4)2SO4 and 0.06 mM Ca(NO3)2·4H2O, respectively; during the second stage of nitrogen treatment, the concentrations of (NH4)2SO4 and Ca(NO3)2·4H2O in Kimura B nutrient were adjusted to 1.44 mM (NH4)2SO4 and 1.71 mM Ca(NO3)2·4H2O.

5. The nitrogen regulation method according to claim 1, characterized in that, The molar ratio of ammonium nitrogen to nitrate nitrogen is 4:

5.

6. The nitrogen regulation method for accelerating rice anther development, accelerating rice flowering time, and improving rice carbon metabolism is characterized by, The nitrogen regulation method is the nitrogen regulation method as described in any one of claims 1 to 5.

7. A method for shortening the growth period of rice, characterized in that, The method includes the following steps: providing a first-stage nitrogen treatment when the number of rice tillers is less than 14, and providing a second-stage nitrogen treatment when the number of rice tillers is not less than 14, wherein, During the first stage of nitrogen treatment, the amount of nitrogen fertilizer used is 0.5~1 mM; During the second stage of nitrogen treatment, the amount of nitrogen fertilizer used is 6-8 mM.

8. The method for shortening the rice growth period according to claim 7, characterized in that, During the first stage of nitrogen treatment, 1.65 mM CaCl2 was added.

9. The method for shortening the rice growth period according to claim 7, characterized in that, Kimura B nutrient solution was used to cultivate rice.

10. The method for shortening the rice growth period according to claim 7, characterized in that, The molar ratio of ammonium nitrogen to nitrate nitrogen is 4:5.

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