A method for predicting the NSC content at the heading stage of large-headed rice based on the photosynthetic capacity at the booting stage of rice

Abstract

The present application relates to rice planting technical field, and particularly relates to a method for predicting NSC content of large-eared rice at heading stage based on photosynthetic potential of rice at booting stage, wherein the leaf area index of 5 days before heading and at heading stage is determined, the photosynthetic potential of 5 days before heading to heading stage is calculated, the stem sheath non-structural carbohydrate concentration of 5 days before heading and at heading stage is determined, the stem sheath non-structural carbohydrate stage accumulation of 5 days before heading to heading stage is calculated, the data of the photosynthetic potential of 5 days before heading to heading stage and the stem sheath non-structural carbohydrate stage accumulation are fitted, and the relationship between the stem sheath non-structural carbohydrate stage accumulation and the photosynthetic potential is obtained. Thus, the stem sheath NSC stage accumulation can be inferred by determining the leaf area index of 5 days before heading and at heading stage to convert the photosynthetic potential, the suitable earing time can be provided with a theoretical basis, and the high-NSC-content variety at heading stage can be screened.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rice planting, and particularly relates to a method for predicting the NSC content of large-eared rice at the heading stage based on the photosynthetic capacity of rice at the booting stage. BACKGROUND

[0002] The storage of stem sheath non-structural carbohydrates (NSC) at the heading stage can enhance the sink strength by promoting the number of endosperm cells, sucrose synthase (SUS) and adenosine diphosphate-glucose pyrophosphorylase (AGP) activity, thereby promoting the initiation of weak grain filling and improving the grain filling and setting. The stem sheath NSC at the heading stage is usually accumulated two weeks before the heading, and is significantly affected by the nitrogen (N) nutrition status of the rice plant. The conventional ear fertilizer is usually applied at the fourth leaf. However, this is not conducive to the accumulation of stem sheath NSC, which is manifested as the stem sheath NSC content of different varieties gradually decreases with the increase of nitrogen application amount at the ear stage. At the same time, with the increase of nitrogen application amount at the fourth leaf, the grain setting rate and grain weight usually show a significant downward trend. The highest stem sheath NSC accumulation and grain filling and setting are usually shown under the condition that no nitrogen fertilizer is applied at the fourth leaf. In addition to the nitrogen application amount of the ear fertilizer, the application time also has a significant effect on the accumulation of stem sheath NSC of rice. It is reported that, under the same N application amount, compared with the fourth leaf fertilization, delaying the nitrogen ear fertilizer to the second leaf can significantly increase the stem sheath NSC content of rice at the heading stage. However, the exact time of nitrogen fertilizer application at the ear stage and the potential process and pathway of increasing the stem sheath NSC content of rice at the heading stage are still unclear.

[0003] At present, the methods for determining the stem sheath NSC content of rice mainly include titration method, anthrone colorimetric method and chromatography method, etc. The titration method is simple to operate, but has low sensitivity and accuracy, and is generally used for the determination of total reducing sugar. The anthrone colorimetric method is the most commonly used rapid and effective method for determining the NSC content, and the determination result represents the total content of all soluble carbohydrates in the solution. The chromatography method is an important method for systematically analyzing the different components and contents of NSC in plant tissues in recent years, but the equipment required by different methods is different, and the application range and determination accuracy are also different. In addition, the above-mentioned methods for determining the stem sheath NSC content of rice all need to be investigated, sampled, dried, ground and sieved before determination, and the determination process is complex and time-consuming, which is not conducive to predicting the grain filling and setting capacity and screening the stem sheath NSC content population at the heading stage before the beginning of rice grain filling.

[0004] In view of the above defects, the present inventors have finally obtained the present application after long-term research and practice. SUMMARY

[0005] The present application aims to solve the problems that the determination of the existing NSC content usually needs to be determined after investigation sampling, drying, grinding and sieving, the determination process is complex, a long time is needed, and real-time monitoring cannot be achieved, and provides a method for predicting the NSC content of large-eared rice at the heading stage based on the photosynthetic potential of rice at the booting stage.

[0006] In order to achieve the above-mentioned purpose, the present application discloses a method for predicting the NSC of large-eared rice at the heading stage based on the photosynthetic potential of rice at the booting stage, comprising the following steps:

[0007] S1, 5 days before heading, at the heading stage, according to the average tiller number in each plot, 2 holes of representative plants are taken, the leaf area index is determined by using a Li-Cor3000 leaf area instrument, and the photosynthetic potential from 5 days before heading to the heading stage is calculated;

[0008] S2, 5 days before heading, at the heading stage, based on the average tiller number in each plot, 2 holes of representative plants are taken, the stem sheath of the plant sample is dried, and the obtained stem sheath dry matter is weighed,

[0009] S3, the stem sheath dry matter dried in step S2 is ground into fine powder and passed through a 1mm sieve, the concentration of stem sheath non-structural carbohydrates is determined by using an anthrone colorimetric method, and the stem sheath non-structural carbohydrate content is calculated;

[0010] S4, according to the stem sheath non-structural carbohydrate content obtained in step S3 from 5 days before heading to the heading stage, the stem sheath non-structural carbohydrate stage accumulation amount from 5 days before heading to the heading stage is calculated, the photosynthetic potential from 5 days before heading to the heading stage obtained in step S1 is fitted with the data of the obtained stem sheath non-structural carbohydrate stage accumulation amount, and the relationship between the stem sheath non-structural carbohydrate stage accumulation amount and the photosynthetic potential is obtained.

[0011] In the step S1, the photosynthetic potential calculation formula is as follows:

[0012] LAD=(L1+L2)×(t2-t1)

[0013] Wherein, LAD is the photosynthetic potential, L1 is the first determined leaf area index, L2 is the second determined leaf area index, t1 and t2 represent the time of the first and second determination of the leaf area index.

[0014] In the step S2, the drying temperature is 80℃, and the drying time is 72h.

[0015] In the step S4, the stem sheath non-structural carbohydrate content is the weight of the stem sheath dry matter multiplied by the concentration of the stem sheath non-structural carbohydrates.

[0016] The rice variety is Huiliangyou 280, and the relationship between the stage accumulation of non-structural carbohydrates of stem sheath obtained in step S4 and the photosynthetic potential is y=-2.50+0.09x, wherein y is the stage accumulation of non-structural carbohydrates of stem sheath from 5 days before heading to the heading stage, and x is the photosynthetic potential from 5 days before heading to the heading stage.

[0017] The rice variety is Yangliangyou 228, and the relationship between the non-structural carbohydrates of stem sheath obtained in step S4 and the photosynthetic potential is y=-3.70+0.12x, wherein y is the stage accumulation of non-structural carbohydrates of stem sheath from 5 days before heading to the heading stage, and x is the photosynthetic potential from 5 days before heading to the heading stage.

[0018] Compared with the prior art, the beneficial effects of the present application are that: by fitting the data of the photosynthetic potential from 5 days before heading to the heading stage and the stage accumulation of stem sheath NSC, the relationship between the photosynthetic potential from 5 days before heading to the heading stage and the stage accumulation of stem sheath NSC is obtained, the determination process is simple, the time required is short, the accumulation of stem sheath NSC can be monitored in real time, the stage accumulation of stem sheath NSC is inferred by converting the leaf area index from 5 days before heading to the heading stage to the photosynthetic potential, and a theoretical basis for inferring the appropriate ear fertilizer time is provided, and the method can also be used for screening high-NSC-content varieties at the heading stage. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 Leaf area index at the heading stage, 15 days after the heading stage, and photosynthetic potential from the heading stage to 15 days after the heading stage under different nitrogen fertilizer treatments;

[0020] Figure 2 Stem sheath dry matter output from the heading stage to 15 days after the heading stage;

[0021] Figure 3 Stem sheath NSC accumulation dynamics;

[0022] Figure 4 Stage dry matter accumulation and photosynthetic potential from 5 days before the heading stage to the heading stage;

[0023] Figure 5 Relationship between the photosynthetic potential and the stage accumulation of stem sheath NSC from 5 days before the heading stage to the heading stage. DETAILED DESCRIPTION

[0024] The above and other technical features and advantages of the present application will be more apparent from the following detailed description taken in conjunction with the accompanying drawings.

[0025] The experiment used two large panicle type hybrid indica rice varieties Hui Liangyou 280 (HLY280) and Yang Liangyou 228 (YLY228) as test materials, four panicle stage nitrogen fertilizer treatments were designed, and panicle fertilizers were applied when the fourth leaf (TL4), third leaf (TL3), second leaf (TL2), and first leaf (TL1) new leaves appeared, respectively. The nitrogen fertilizer treatments are shown in Table 1. In all treatments, 112.5 kg ha -1 Phosphorus fertilizer (P2O5) and 180 kg ha -1 Potassium fertilizer (KCl) was mixed into the soil before transplanting. Water was separated by agricultural film, and independent irrigation was used.

[0026] Rice was grown in hard disks on May 18, 2021 and May 19, 2022, with 80 g of dry valley per disk. Artificial transplanting was performed on June 15, 2021 and June 16, 2022, with a row spacing of 33 cm x 16 cm and 2 seedlings per hole. During the entire rice growing season, until physiological maturity was reached, irrigation was performed to a depth of 5 ± 2 cm above the soil surface. Disease and pest management was the same as local high-yield cultivation.

[0027] Table 1 Description of nitrogen fertilizer treatments

[0028]

[0029] Determination of rice growth stages: 50% of the rice panicles in the plot were exposed to the leaf sheath as the heading stage, and 90% of the grains in each panicle were yellow and the base of the rice panicle was hard as the mature stage.

[0030] 1. Yield determination: After the rice matured, 10 holes of rice were taken in each plot to determine the yield components (effective panicle number, grain number per panicle, seed setting rate, and grain weight), and the theoretical yield was calculated. The yield and its components under different panicle stage nitrogen fertilizer treatments are shown in Table 2.

[0031] Table 2 Yield and its components under different nitrogen fertilizer treatments

[0032]

[0033] 2. Dry matter accumulation determination

[0034] At 20, 15, 10, 5 days before heading, at the heading stage, 15 days after heading, and at the mature stage, based on the average tiller number in each plot, 2 representative plants were taken. All plant samples were divided into leaves, stems, and panicles (when present). The dry matter of each component was dried at 80°C for 72 hours and weighed. The aboveground dry matter accumulation and harvest index under different nitrogen fertilizer treatments are shown in Table 3.

[0035] Table 3 Aboveground dry matter weight and harvest index under different nitrogen fertilizer treatments

[0036]

[0037]

[0038] 3. Calculation of leaf area index

[0039] Leaf area index: 2 representative plants were selected according to the average tiller number in each plot at 5 days before heading, at heading and 15 days after heading. Leaf area was measured by Li-Cor 3000 area meter and leaf area index was calculated. The formula for calculating leaf area index is as follows:

[0040] LAD (m 2 m -2 2) = (L1+L2) x (t2-t1)

[0041] Where L1 and L2 represent the first and second measured leaf area index (m 2 m -2 2), t1 and t2 represent the time of the first and second measurement of leaf area index.

[0042] Figure 1 For leaf area index at heading and 15 days after heading, and photosynthetic capacity from heading to 15 days after heading, it was found that TL3 treatment did not have obvious advantages in leaf area index at heading and 15 days after heading, and the photosynthetic capacity corresponding to the period from heading to 15 days after heading also did not have obvious advantages. Therefore, the significant high stage of dry matter accumulation of TL3 from heading to 15 days after heading was not due to the leaf area index during this period.

[0043] Figure 2 For stem sheath dry matter output from heading to 15 days after heading, it was found that the high dry matter accumulation during this period was due to the high stem sheath dry matter output.

[0044] 4. Determination of NSC and data fitting

[0045] The stem sheath dry matter was ground into fine powder and filtered through a 1 mm sieve. The anthrone colorimetric method was used to determine the concentration of stem sheath NSC, and the stem sheath NSC content (tha -1 ) was calculated as the weight of stem sheath dry matter multiplied by the NSC concentration. The accumulation and transport of stem sheath NSC under different nitrogen fertilizer treatments are shown in Table 4.

[0046] Table 4 Accumulation and transport of stem sheath NSC under different nitrogen fertilizer treatments

[0047]

[0048] Figure 3For the accumulation dynamics of stem sheath NSC, by comparing the accumulation dynamics of stem sheath NSC, it is found that the high stem sheath NSC content at the heading stage is mainly due to the high stem sheath NSC stage accumulation amount from 5 days before heading to the heading stage.

[0049] Figure 4 For the stage dry matter accumulation and photosynthetic potential from 5 days before heading to the heading stage, by comparison, it is found that TL3 has significantly high stage dry matter accumulation and photosynthetic potential. Therefore, the high stem sheath NSC at the heading stage may be related to the significantly high photosynthetic potential from 5 days before heading to the heading stage, which promotes the stem sheath NSC stage accumulation amount from 5 days before heading to the heading stage.

[0050] By comparing the relationship between the photosynthetic potential from 5 days before heading to the heading stage and the stem sheath NSC stage accumulation amount, it is found that they have a significant positive correlation relationship, and the relationship between the photosynthetic potential from 5 days before heading to the heading stage and the stem sheath NSC stage accumulation amount is as shown in Figure 5

[0051] The above only describes the preferred embodiments of the present application, which are only illustrative but not limiting. It is understood by those skilled in the art that many changes, modifications and even equivalents can be made to the present application within the spirit and scope defined by the claims of the present application, but all will fall within the protection scope of the present application.​

Claims

1. A method for predicting NSC content at the heading stage of large-panicle rice based on photosynthetic potential during the booting stage, characterized in that, Includes the following steps: S1. Five days before heading and during the heading period, two representative plants were selected from each plot based on the average number of tillers. The leaf area index was measured using a Li-Cor3000 leaf area meter, and the photosynthetic potential from five days before heading to the heading period was calculated. S2, 5 days before heading, during the heading stage, based on the average number of tillers in each plot, two representative plants were selected. The stem sheaths of the plant samples were dried, and the dry matter obtained from the stem sheaths was weighed. S3, grind the dried stem and sheath dry matter from step S2 into fine powder and pass it through a 1mm sieve. Use the anthrone colorimetric method to determine the concentration of non-structural carbohydrates in the stem and sheath, and calculate the content of non-structural carbohydrates in the stem and sheath. S4. Based on the non-structural carbohydrate content of stems and sheaths obtained in step S3, calculate the accumulation of non-structural carbohydrates in stems and sheaths from 5 days before heading to the heading stage. Fit the photosynthetic potential obtained in step S1 from 5 days before heading to the heading stage with the data of the accumulation of non-structural carbohydrates in stems and sheaths to obtain the relationship between the accumulation of non-structural carbohydrates in stems and sheaths and the photosynthetic potential. In step S1, the formula for calculating photosynthetic potential is as follows: LAD = ( L 1+ L 2) × ( t 2 – t 1) LAD stands for photosynthetic potential. L 1 represents the leaf area index measured for the first time. L 2 represents the leaf area index measured for the second time. t 1 and t 2 indicates the time of the first and second leaf area index measurements; In step S4, the content of non-structural carbohydrates in the stem and sheath is the dry weight of the stem and sheath multiplied by the concentration of non-structural carbohydrates in the stem and sheath.

2. The method for predicting NSC content at the heading stage of large-panicle rice based on photosynthetic potential during the booting stage, as described in claim 1, is characterized in that... In step S2, the drying temperature is 80°C and the drying time is 72 hours.

3. The method for predicting NSC content at the heading stage of large-panicle rice based on photosynthetic potential during the booting stage, as described in claim 1, is characterized in that... The rice variety is Huiliangyou 280. The relationship between the accumulation of non-structural carbohydrates in the stem and sheath and photosynthetic potential obtained in step S4 is as follows: y =-2.50+0.09 x ,in, y This refers to the accumulation of non-structural carbohydrates in the stem and sheath during the five days before heading and the heading stage. x The photosynthetic potential is measured from 5 days before heading to the heading stage.

4. The method for predicting NSC content at the heading stage of large-panicle rice based on photosynthetic potential during the booting stage, as described in claim 1, is characterized in that... The rice variety is Yangliangyou 228. The relationship between the non-structural carbohydrates in the stem sheath and photosynthetic potential obtained in step S4 is as follows: y =-3.70+0.12 x ,in, y This refers to the accumulation of non-structural carbohydrates in the stem and sheath during the five days before heading and the heading stage. x The photosynthetic potential is measured from 5 days before heading to the heading stage.

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