A method for improving the panicle type index of the number of grains per panicle of rice by applying fertilizer at the panicle stage and application thereof

Abstract

This invention relates to the field of scientific fertilization and production technology for rice, specifically to a method and application of panicle-stage fertilization to stabilize the number of grains per panicle and improve the panicle type index. The fertilization period is the third leaf from the bottom, which is the stage from the third leaf from the bottom until it is fully expanded. The fertilization amount is 110 kg / ha. ‑1 The fertilizer is urea, and the total nitrogen content of the urea is ≥46%. The nitrogen management method during the heading stage of this invention stabilizes the number of grains per panicle while improving the panicle shape index, thus resolving the synergistic contradiction between the number of grains per panicle and the grain fillability. Compared with the conventional method of applying nitrogen fertilizer during the heading stage at the three-leaf stage, this invention can cultivate a grain-setting characteristic dominated by grains in the middle and upper parts of the panicle, increasing the rice panicle shape index by 8.8%–10.0% and achieving a yield increase of 8.8%–9.1%.

Description

Technical Field

[0001] This invention relates to the field of scientific fertilization and production technology for rice, specifically to a method for fertilizing during the panicle stage to stabilize the number of grains per panicle and improve the panicle type index, and its application. Background Technology

[0002] Rice is a crucial food crop in my country, with over 60% of the population relying on it as their staple food. Under high-yield cultivation, rice yield is significantly influenced by panicle capacity, which is closely related to the grain placement position of the grains on the panicle. Compared to the upper and middle parts of the panicle, grains on the lower secondary branches flower later, fill slowly, have lower seed setting rate and grain weight, resulting in lower and less stable yields. In short, with the same number of grains per panicle, increasing the proportion of spikelets on the upper and middle secondary branches is beneficial for improving rice panicle capacity and yield. Currently, the panicle type index (the ratio of the node of the primary branch with the most grains on the secondary branch to the number of primary branches) is widely used to quantitatively describe the grain placement characteristics of rice panicles, and maintaining a high panicle type index is considered an optimized panicle structure. The above indicates that, under the premise of stabilizing the number of grains per panicle, shaping a panicle structure dominated by grain placement on the upper and middle secondary branches and improving the panicle type index is a powerful approach for current high-yield rice cultivation.

[0003] The timing of nitrogen application significantly affects panicle differentiation and grain number per panicle in rice. Applying nitrogen fertilizer at the four-leaf stage (early panicle differentiation) is currently the main agronomical measure to increase the number of grains per panicle in rice production. Chinese invention patent CN202010654280.3 discloses a rice fertilization method that mainly improves rice yield by more than 5% through nitrogen fertilizer management at the four-leaf stage. Chinese invention patent CN202211289051.1 discloses a fertilization method that promotes the synergistic effect of quantity and quality in rice production. By creating different nitrogen fertilizer application gradients at the four-leaf stage, it maintains a high number of grains per panicle and yield in the rice population, achieving a synergistic effect of high yield and high quality. However, traditional fertilization methods at the four-leaf stage mainly increase the number of grains per panicle by increasing the number of grains on the secondary branches of the lower panicle. This method mainly focuses on increasing the number of grains in the middle and lower panicles, making it difficult to stabilize the number of grains per panicle while improving the panicle type index. This is not conducive to improving the stock capacity and limits the yield potential of rice, especially large-panicle rice.

[0004] In view of the above-mentioned defects, the inventors of this invention have finally obtained this invention after a long period of research and practice. Summary of the Invention

[0005] The purpose of this invention is to address the problem that traditional fertilization methods for the four-leaf stage mainly increase the number of grains per panicle by increasing the number of grains on the secondary branches of the lower panicle. This method focuses on increasing the number of grains in the middle and lower panicles, making it difficult to stabilize the number of grains per panicle while simultaneously improving the panicle type index. This is not conducive to improving the stock capacity and limits the yield potential of rice, especially large-panicle rice. The invention provides a panicle-stage fertilization method that stabilizes the number of grains per panicle and improves the panicle type index, as well as its application.

[0006] To achieve the above objectives, this invention discloses a method for fertilizing during the panicle stage to stabilize the number of grains per panicle and improve the panicle type index. Basal tiller fertilizer is applied one day before transplanting, and nitrogen panicle fertilizer is applied at the three-leaf stage.

[0007] The term "penultimate leaf" refers to the stage from the third leaf from the end of its life to its full expansion, and the period of the penultimate leaf is 48 days to 52 days.

[0008] The nitrogen fertilizer application rate is 110 kg ha. -1 .

[0009] The nitrogen fertilizer used for ear of grain is urea.

[0010] The total nitrogen content of the urea must be ≥46%.

[0011] The nitrogen fertilizer was applied manually and evenly to the paddy field during the three-leaf stage from the top.

[0012] The mass ratio of the basal tiller fertilizer to the nitrogen-containing spike fertilizer is 1:1.

[0013] The basal fertilizer is urea.

[0014] The total nitrogen content of the urea must be ≥46%.

[0015] This invention also discloses the application of the above-mentioned method of fertilizing during the panicle stage to stabilize the number of grains per panicle and improve the panicle type index in indica hybrid rice.

[0016] Applying topdressing fertilizer at the four-leaf stage mainly affects the number of grains per ear by increasing the content of CTK and the number of floret differentiation. Applying topdressing fertilizer at the three-leaf stage mainly affects the number of grains per ear by reducing the content of auxin and ethylene, inhibiting apical dominance and ethylene synthesis, and reducing the number of degenerated florets.

[0017] Compared with existing technologies, the beneficial effects of this invention are as follows: Compared with fertilization at the four-leaf stage, this invention reduces the content of endogenous auxin and ethylene in rice by applying nitrogen fertilizer at the three-leaf stage, inhibiting apical dominance and ethylene synthesis. This primarily reduces the number of secondary spikelets degenerating in the middle of the panicle, achieving a stable number of grains per panicle while increasing the number of grains in the upper and middle parts, creating a better panicle structure, improving the panicle type index, optimizing grain fillability, and solving the key problem limiting yield increase. Compared with conventional nitrogen fertilizer application at the four-leaf stage, nitrogen fertilizer application at the three-leaf stage can increase the panicle type index of II Youming 86 and Jingliangyou 8612 by 10.0% and 8.8% respectively, achieving yield increases of 9.1% and 8.8%. It also provides technical support and research directions for breeders in selecting rice varieties. Attached Figure Description

[0018] Figure 1 The distribution of grain number per ear at different ear positions of II Youming 86 and Jingliangyou 8612 under the treatments of Examples 1, 2, 3 and Comparative Example 1 of this invention is shown below. T: upper part of ear, M: upper part of ear, B: lower part of ear.

[0019] Figure 2 The following figures illustrate the number and distribution of spikelet differentiation at different positions in II Youming 86 and Jingliangyou 8612 under the treatments of Examples 1, 2, 3 and Comparative Example 1 of this invention: TP: primary spikelet at the top of the spike, TS: secondary spikelet at the top of the spike, MP: primary spikelet in the middle of the spike, MS: secondary spikelet in the middle of the spike, BP: primary spikelet at the bottom of the spike, and BS: secondary spikelet at the bottom of the spike.

[0020] Figure 3 The following figures illustrate the number and distribution of degenerated spikelets at different positions on the spikes of II Youming 86 and Jingliangyou 8612 under the treatments of Examples 1, 2, 3 and Comparative Example 1 of this invention: TP: primary spikelet on the upper part of the spike, TS: secondary spikelet on the upper part of the spike, MP: primary spikelet on the middle part of the spike, MS: secondary spikelet on the middle part of the spike, BP: primary spikelet on the lower part of the spike, and BS: secondary spikelet on the lower part of the spike.

[0021] Figure 4 The ear type index of II Youming 86 and Jingliangyou 8612 under the treatments of Examples 1, 2, 3 and Comparative Example 1 of this invention;

[0022] Figure 5 The content of growth-promoting hormones and the number of degenerated spikelets per spike in Jingliangyou 8612 under the treatment of Example 1 and Comparative Example 1 of this invention;

[0023] Figure 6 The content of growth-inhibiting hormones and the number of degenerated spikelets per spike were determined by the treatments in Example 1 and Comparative Example 1 of this invention.

[0024] Figure 7The spikelet type index of II Youming 86 and Jingliangyou 8612 under the treatment of Examples 1, 4 and 5 of the present invention. Detailed Implementation

[0025] The above-mentioned and other technical features and advantages of the present invention will be described in more detail below with reference to the accompanying drawings.

[0026] The experiment was conducted in 2022 at the Lujiang Experimental Base of Anhui Agricultural University (31°48′N, 117°23′E).

[0027] The example uses the amount of fertilizer applied at the three-leaf stage from the top, while the comparison uses the conventional application of fertilizer at the four-leaf stage from the top.

[0028] The experimental varieties, II Youming 86 and Jingliangyou 8612, are hybrid indica rice varieties that are widely planted in Anhui, Hubei and other places.

[0029] Example 1

[0030] A method for fertilizing during the panicle stage to stabilize the number of grains per panicle and improve the panicle type index in rice specifically includes:

[0031] (1) Apply basal fertilizer one day before transplanting;

[0032] The application rate of base fertilizer is: 110 kg / ha of nitrogen fertilizer. -1 ;

[0033] The nitrogen fertilizer in the above-mentioned basal tiller fertilizer is urea;

[0034] The total nitrogen content of the above-mentioned urea is ≥46%.

[0035] (2) Applying fertilizer during the heading stage

[0036] The timing for applying top dressing is the third leaf from the bottom; the third leaf from the bottom refers to the stage from when the third leaf from the end has fully expanded.

[0037] The application rate of topdressing fertilizer is 110 kg ha -1 ;

[0038] The total nitrogen content of the above-mentioned urea is ≥46%.

[0039] The mass ratio of basal fertilizer to panicle fertilizer is 1:1.

[0040] Example 2

[0041] A method for fertilizing during the panicle stage to stabilize the number of grains per panicle and improve the panicle type index in rice is basically the same as that in Example 1, except that:

[0042] The timing for applying top dressing fertilizer is when the fifth leaf from the bottom has fully expanded.

[0043] Example 3

[0044] A method for fertilizing during the panicle stage to stabilize the number of grains per panicle and improve the panicle type index in rice is basically the same as that in Example 1, except that:

[0045] The timing for applying top dressing fertilizer is the second leaf from the bottom; the second leaf from the bottom refers to the stage from when the second to last leaf has fully expanded.

[0046] Example 4

[0047] A method for fertilizing during the panicle stage to stabilize the number of grains per panicle and improve the panicle type index in rice is basically the same as that in Example 1, except that:

[0048] The application rate of topdressing fertilizer is 80 kg ha -1 ;

[0049] The total nitrogen content of urea is ≥46%.

[0050] The mass ratio of basal fertilizer to panicle fertilizer is 11:8.

[0051] Example 5

[0052] A method for fertilizing during the panicle stage to stabilize the number of grains per panicle and improve the panicle type index in rice is basically the same as that in Example 1, except that:

[0053] The application rate of topdressing fertilizer is 140 kg ha -1 ;

[0054] The total nitrogen content of the above-mentioned urea is ≥46%.

[0055] The mass ratio of basal fertilizer to panicle fertilizer is 11:14.

[0056] Comparative Example 1

[0057] Comparative Example 1 is basically the same as Example 1, except that:

[0058] The timing for applying top dressing fertilizer is when the fourth leaf from the bottom has fully expanded.

[0059] The effects of nitrogen topdressing timing on the number of grains per panicle and panicle type index in Examples 1-3 and Comparative Example 1 were compared, and the results are as follows:

[0060] 1. Determination of actual rice yield and grain number distribution at different panicle positions

[0061] At the rice maturity stage, 100 hills were harvested from the unsampled areas in the center of each plot, dried, and the grain quality and moisture content were measured. The actual yield was calculated based on the moisture content of 13.5%. The results of the rice yield and composition measurements are shown in Table 1.

[0062] As shown in Table 1, compared with Examples 2 and 3, the actual yield of Example 1 increased by 1.3% to 23.5%, mainly by significantly increasing the number of grains per ear. Compared with Comparative Example 1, there was no significant difference in the number of grains per ear in Example 1, but the seed setting rate increased by 9.0% to 10% and the thousand-grain weight increased by 1.3% to 1.5%, thus achieving increased yield. The two varieties showed consistent performance.

[0063] At the rice maturity stage, representative plants from each plot were seeded in 8 holes, and the distribution of grains per panicle at different panicle positions was measured. The results are shown in […]. Figure 1 .

[0064] Depend on Figure 1 It can be seen that the number of grains per ear at different positions in II Youming 86 and Jingliangyou 8612 showed significant differences in response to different treatments. For II Youming 86, the number of grains per ear in the lower part of the ear in the treatment of Example 1 was significantly higher than that in Example 2, Example 3 and Comparative Example 1. For Jingliangyou 8612, the number of grains per ear in the middle part of the ear in the treatment of Example 1 was significantly higher than that in Example 2, Example 3 and Comparative Example 1. This indicates that the fertilization treatment at the three-leaf stage can change the ear structure of the two varieties.

[0065] Table 1. Rice yield and number of grains per panicle in Comparative Examples 1 and Examples 1-3

[0066]

[0067] Where: a, b, and c represent differences at the 0.05 level for the same variety.

[0068] 2. Determination of differentiation and degeneration of spikelets at different panicle positions in rice

[0069] Ten main stems of uniform growth were selected during the rice heading stage (when the panicle has emerged 1 / 3 to 1 / 2 of its length) for measuring spikelet differentiation and degeneration. The number of differentiated and degenerated spikelets at different panicle positions was observed and recorded. Degenerated spikelets were characterized by small, white, membranous traces; some were visible to the naked eye and counted, while others with smaller degeneration traces were observed and counted under a stereomicroscope. The results of the measurement of spikelet differentiation and degeneration numbers at different panicle positions are shown below. Figure 2 , Figure 3 The number of existing, differentiated, and degenerated spikelets per panicle of rice is shown in Table 2.

[0070] Depend on Figure 2It can be seen that the number of primary spikelets at different ear positions in II Youming 86 and Jingliangyou 8612 showed no significant difference in response to different treatments, but the number of secondary spikelets at different ear positions showed highly different responses to different treatments. In Example 1 (fertilization at the third leaf from the bottom), the number of secondary spikelets at different ear positions was significantly higher than in Examples 2 and 3, consistent with the performance of the two varieties. Compared with Comparative Example 1, the number of secondary spikelets in the middle of the ear increased by 10% in II Youming 86 under the treatment of Example 1, while the number of secondary spikelets in the lower middle of the ear increased by 8.8% in Jingliangyou 8612 under the treatment of Example 1. Figure 3 It can be seen that the number of primary and secondary florets degenerated at different ear positions in II Youming 86 and Jingliangyou 8612 responded differently to different treatments. In Example 1 (fertilization at the third leaf from the top), the number of primary and secondary florets degenerated at different ear positions was significantly lower than in Examples 2 and 3, and the two varieties showed consistent performance. Compared with Comparative Example 1, II Youming 86 reduced the number of primary and secondary florets degenerated in the middle and lower parts of the ear by 21.8%–42.9% and 1.3%–12.6% respectively under the treatment in Example 1; Jingliangyou 8612 reduced the number of primary and secondary florets degenerated in the middle part of the ear by 5.9%–48.8% under the treatment in Example 1.

[0071] Table 2 shows that the number of existing, differentiated, and degenerated spikelets per spike of II Youming 86 and Jingliangyou 8612 responded differently to different treatments. The number of existing and differentiated spikelets per spike in Example 1 was significantly higher than that in Examples 2 and 3, while the number of degenerated spikelets per spike was significantly lower than that in other examples, showing consistent performance between the two varieties. Compared with Comparative Example 1, the number of differentiated spikelets per spike of II Youming 86 and Jingliangyou 8612 in Example 1 was slightly lower than that in Comparative Example 1, but the number of degenerated spikelets per spike was significantly lower than that in Comparative Example 1, with no difference in the number of existing spikelets per spike.

[0072] Table 2. Number of extant, differentiated, and degenerated spikelets per spike in Comparative Examples 1 and Examples 1-3

[0073]

[0074] 3. Determination of Rice Panicle Type Index

[0075] According to the definition of panicle type index: the ratio of the node of the primary branch with the most grains to the number of primary branches, the panicle type index was determined by taking 8 representative plants at maturity and measuring the panicle type index. The results are shown in […]. Figure 4 .

[0076] Depend on Figure 4It can be seen that different treatments significantly affected the ear type index of II Youming 86 and Jingliangyou 8612. In the examples, compared with Examples 2 and 3, the treatment in Example 1 increased the ear type index of II Youming 86 and Jingliangyou 8612 by 17.7%–22.8% and 11.4%–12.12%, respectively. Compared with Comparative Example 1, Example 1 increased the ear type index of II Youming 86 and Jingliangyou 8612 by 11.0% and 8.8%, respectively.

[0077] 4. Determination of endogenous hormones in rice

[0078] Twelve days after panicle differentiation, young panicle samples of Jingliangyou 8612 rice under fertilization treatments at the four-leaf and three-leaf stages were selected for hormone extraction and determination. The results are shown in […]. Figure 5 , Figure 6 .

[0079] Depend on Figure 5 It was found that different treatments significantly affected the concentration of growth-promoting plant hormones and the CTK / IAA ratio in Jingliangyou 8612. Compared with fertilization at the four-leaf stage, fertilization at the three-leaf stage had no effect on CTK concentration, but significantly reduced IAA concentration by 24.1% and increased the CTK / IAA ratio by 26.2%.

[0080] Depend on Figure 6 It was found that different treatments significantly affected the concentration of growth-inhibiting hormones and the ABA / ACC ratio of Jingliangyou 8612. Compared with fertilization at the four-leaf stage, fertilization at the three-leaf stage significantly increased the ABA concentration by 110.4% and the ABA / ACC ratio by 182.7%, while decreasing the ACC concentration by 25.5%.

[0081] The effects of nitrogen fertilizer application rate on the number of grains per panicle and panicle type index in Examples 1, 4, and 5 are compared and the results are as follows:

[0082] 1. Determination of actual rice yield and yield composition

[0083] At the rice maturity stage, 100 hills were harvested from the unsampled areas in the center of each plot, dried, and the grain quality and moisture content were measured. The actual yield was calculated based on the moisture content of 13.5%. The results of the rice yield and composition measurements are shown in Table 3.

[0084] As shown in Table 3, the yield in Example 1 was significantly higher than that in Examples 4 and 5. This was mainly due to the higher number of grains per ear and the higher seed setting rate in Example 1, indicating that the application of 110 kg ha at the three-leaf stage was effective. -1 The appropriate amount of urea is the most suitable nitrogen application rate.

[0085] Table 3. Rice yield and yield composition in Examples 1, 4 and 5

[0086]

[0087] Note: a, b, and c represent differences at the 0.05 level for the same variety.

[0088] 2. Determination of Rice Panicle Type Index

[0089] According to the definition of panicle type index: the ratio of the node of the primary branch with the most grains to the number of primary branches, the panicle type index was determined by taking 8 representative plants at maturity and measuring the panicle type index. The results are shown in […]. Figure 7 .

[0090] Depend on Figure 7 It can be seen that the ear shape index of II Youming 86 and Jingliangyou 8612 under Example 1 is 9.4% to 14.3% and 6.8% to 10.8% higher than that of the other examples, respectively. This indicates that compared with other examples, the grains of the two varieties under the treatment of Example 1 are mainly concentrated in the middle and upper part of the ear.

[0091] The results in summary indicate that the nitrogen management method during the heading stage provided by this invention helps stabilize the number of grains per panicle in rice, improves the panicle type index, resolves the contradiction between the number of grains per panicle and the fullness of the panicle, and ultimately increases the relative yield. Compared with Comparative Example 1 (conventional four-leaf panicle), Example 1 (three-leaf panicle) mainly inhibits apical dominance and reduces ethylene synthesis by reducing the content of endogenous auxin and ethylene in rice, thereby reducing the number of secondary spikelets degenerated in the middle of the panicle and increasing the number of grains in the upper and middle parts of the panicle. This increases the panicle type index of II Youming 86 and Jingliangyou 8612 by 10.0% and 8.8%, respectively, resulting in yield increases of 9.1% and 8.8%. This demonstrates that the nitrogen management method during the heading stage of this invention can effectively increase yield by stabilizing the number of grains per panicle while improving the panicle type index.

[0092] The above description is merely a preferred embodiment of the present invention and is illustrative rather than restrictive. Those skilled in the art will understand that many changes, modifications, and even equivalents can be made within the spirit and scope defined by the claims of the present invention, all of which will fall within the protection scope of the present invention.

Claims

1. The use of a panicle type index of panicle grain number increasing method by panicle stage fertilization in medium indica hybrid rice, characterized in that, The base tiller fertilizer is applied one day before transplanting, and the nitrogen ear fertilizer is applied at the three-leaf stage; the three-leaf stage is the stage that the third leaf from the bottom is stretched out to fully unfolded, the three-leaf stage is 48d-52d; the nitrogen ear fertilizer application amount is 110kg / ha -1 ; the application mass ratio of the base tiller fertilizer and the nitrogen ear fertilizer is 1:

1.

2. The use of the method for stabilizing the panicle type index of the number of grains per panicle of rice by panicle stage fertilization according to claim 1 in medium indica hybrid rice, characterized in that, The nitrogen panicle fertilizer is urea.

3. The use of the method for stabilizing the panicle type index of the number of grains per panicle of rice by panicle stage fertilization according to claim 2 in medium indica hybrid rice, characterized in that, The total nitrogen of the urea is ≥ 46%.

4. The use of the method for stabilizing the panicle type index of the number of grains per panicle of rice by panicle stage fertilization according to claim 1 in medium indica hybrid rice, characterized in that, The nitrogen panicle fertilizer is manually and uniformly applied to the paddy field at the three-leaf stage.

5. The use of the method for stabilizing the panicle type index of the number of grains per panicle of rice by panicle stage fertilization according to claim 1 in medium indica hybrid rice, characterized in that, The basal fertilizer is urea.

6. The use of the method for stabilizing the panicle type index of the number of grains per panicle of rice by panicle stage fertilization according to claim 5 in medium indica hybrid rice, characterized in that, The total nitrogen of the urea is ≥ 46%.

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