Correlation Between Photosynthetic Characteristics And Yield Structure Of Soybean And Its Physiological Basic Research

Soybean(Glycine max L.Merrill)is an important oil crop and the most important plant protein source for human beings.High photosynthetic efficiency is an important factor for soybeans to obtain high yields.In this experiment,four soybean varieties,Lindou 9(LD9),Weidou 9(WD9),Hedou 12(HD12),and Qihuang34(QH34),were selected as the test materials,which were selected and bred in Shandong Province in recent years.They have the advantages of small growth period differences and outstanding variety characteristics.The purpose is to study the changes of photosynthetic characteristics of the three canopies of soybean at different growth stages,and to explore the correlation between photosynthetic characteristics and yield.The main test results are as follows:1.The correlation between main agronomic traits and yield was clarifiedThe dry matter accumulation of soybean showed an “S”-shaped curve,and the peak value appeared in the R4-R6 stages.The high-yield variety QH34 still maintained a high dry matter accumulation level in the later stages of growth.There was a positive correlation between dry matter accumulation and yield,and the biomass accumulated during the R6-R8 stages had the greatest effect on the final soybean grain yield formation.Maintaining a large leaf area during the R2 and R4 stages and delaying leaf senescence is the physiological basis for improving dry matter accumulation and achieving high yield in the later stages of growth.Hundred-grain weight,biological yield and harvest index are important indicators of high-yield soybean breeding.2.The changes of photosynthetic characteristics and senescence enzymes in different canopies of different varieties,and the correlation between photosynthetic characteristics and yield were clarifiedThe peak values of Pn,Gs and Tr of LD9 and WD9 appeared in R2 stage.The peaks values of Pn,Gs and Tr of HD12 and QH34 appeared in R4 stage and remained high in the R2 to R6 stages.Increasing the Pn and Gs in the podding stage and grain filling stage of the soybean,andsynergistically delaying the decline of the SPAD value in the senescence stage,are the photosynthetic physiological basis for increasing soybean yield.The Pn,Gs and Tr of the first and second canopies were higher than those of the third canopy.Therefore,the upper and middle canopy are the optimal leaf positions for measuring soybean yield status because of its outstanding photosynthetic characteristics.The activities of SOD,CAT and POD in soybean showed a single peak with the growth stages.The activities of SOD and CAT in the first and second canopies were higher than those in the third.The high activities of SOD,CAT and POD in QH34 are the physiological basis of its high yield.3.The chlorophy? fluorescence characteristics of different canopies between varieties and their correlation with yield were clarifiedThe peak values of ?PSII and qP appeared in the stages of R4 to R6,which were positively correlated with yield in different growth stages.They were important internal reference for soybean yield prediction and evaluation.The Fv/Fm,?PSII and qP of the first and second canopy leaves were higher than those of the third canopy,which had higher potential photosynthetic capacity.They are an ideal combination of leaf positions for evaluating the fluorescence characteristics of soybeans.The ?PSII and qP of the first and second canopy of QH34 and HD12 were higher than those of the third canopy,which were consistent with the change rule of Pn among the three canopy,and were the internal response to photosynthesis.4.The daily changes of photosynthesis of different types of summer soybean varieties and their correlation with yield were clarifiedThe diurnal variation of photosynthetic rate did not follow the inherent pattern,and the highest peak appeared at 10:00.The average daily photosynthetic rate of high-yield QH34 was significantly higher than that of other varieties during the R6-R7 stages.During the R4-R6 stages,the yield was significantly positively correlated with the daily mean value of Pn and the daily mean value of ?PS?,and it is significantly negatively correlated with the Ci daily mean.In R6-R7 stages,the daily mean value of Gs was positively correlated with the yield.The daily changes of Pn,Gs and ?PS? in the middle and late growth stages are important indicators foridentification and evaluation of high-yield and high-light-efficiency varieties.