Photosynthetic Characteristics Of Super High-yield Soybean And Its Response To Nitrogen Fertilizer

The photosynthetic rate is one of the main indicators for studying the photosynthetic physiology of plants,and improving photosynthetic rate of crops has a good effect on increasing yield.By using the three-dimensional model and constructing a three-dimensional soybean canopy model,simulation of the canopy light distribution is performed to provide theoretical guidance for the selection and breeding of highyield soybeans.Compared with the single leaf photosynthetic rate,the population photosynthetic rate can accurately show the relationship between photosynthesis and yield,which is of great significance for increasing soybean yield.Reasonable application of nitrogen fertilizer can effectively increase the net photosynthetic rate of soybean leaves.The systematic study of the photosynthetic characteristics of superhigh-yield soybeans and the response to nitrogen fertilizer has guiding significance for the selection and cultivation of super-high-yield soybeans.This experiment uses a combination of potted and field methods,using super-high-yield soybean varieties(Jiyu86)and ordinary soybean varieties(Jiyu 593)as the test materials.The field experiment draws a three-dimensional model of soybean canopy structure by measuring plant parameters in different growth periods,and simulates the canopy light distribution of soybean leaves in different growth periods.Population photosynthesis was measured at different times using CAPTS-100 to explore the ideal plant type for ultra-highyielding varieties and the population photosynthetic characteristics of ultra-highyielding varieties.The pot experiment was conducted with the ultra-high-yielding variety Jiyu 86 and set to five nitrogen application levels: N0,N1,N2,N3,and N4,respectively,to investigate the effects of nitrogen levels on the photosynthetic rate of soybean leaves and soybean yield.The results of the study showed that:(1)The three-dimensional canopy structure model and canopy light distribution simulation of soybean at different fertility stages showed that Jiyu 86 had small petiole angle,good canopy structure,compact plant shape,and met the criteria of ideal plant shape.(2)The daily variation of net photosynthetic rate of single leaves of Jiyu 86 and Jiyu 593 was bimodal,with peaks at 11:00 a.m.and 15:00 p.m.;the population canopy photosynthetic rate of the two varieties behaved differently in different weather,with no fixed pattern.Jiyu 86 was in sunny weather.The daily variation of canopy photosynthetic rate showed a bimodal curve,with the first peak at 10 a.m.Under cloudy and rainy weather conditions,the canopy photosynthetic rate of Jiyu86 showed a singlepeaked pattern.The population canopy photosynthetic rate of Jiyu 86 was higher than that of Jiyu 593 in any weather,indicating that Jiyu 86 has higher photosynthetic potential than Jiyu 593 and can adapt to different light environment changes.(3)The net photosynthetic rates of Jiyu 86 and Jiyu 593 in the upper and middle canopies increased continuously with increasing photosynthetic effective radiation,and the maximum photosynthetic rate in the lower canopy occurred when the PAR of photosynthetic effective radiation was 1500μmol m?2s?1,and the net photosynthetic rate started to decrease when the PAR of photosynthetic effective radiation was >1500 μmol m?2s?1.The net photosynthetic rate of Jiyu 86 was higher than that of Jiyu 593 in different canopy layers.(4)The leaf area index of Jiyu 86 was 32% higher than that of Jiyu 593 at pod stage and reached a significant difference level,indicating that maintaining a higher leaf area index at pod stage plays a good role in improving crop yield.(5)With increasing N application,the net photosynthetic rate and leaf color value of Jiyu86 reached the maximum value at N3 treatment;the leaf color value and net photosynthetic rate of Jiyu86 were the largest at the peak pod stage,and the net photosynthetic rate and yield of leaves at the peak pod stage formed a significant positive correlation;the net photosynthetic rate of Jiyu86 showed a gradual decrease from the prime leaves under different N application levels;the yield of Jiyu86 was the highest under N3 treatment.The highest yield was obtained under N3 treatment.