Study On Some Agronomic Traits Of Soybean Cultivars With Year Of Release In Jilin Province

From 1920s,soybean production has increased with genetic improvement and progress of cultivating,extensively.Agronomic,physiological and quality traits changed with increase of yield significantly.The relationships among yield,biomass and canopy structures were hardly reported recently.Our objective was to investigate the changes of yield,biomass,oil and protein content in order to understand the physiological basis in the selection of historical cultivars using 30 soybean cultivars cultivated and genetically improved from 1923 to 2005.Via relative analysis of yield,some agronomic traits and different stages,harvest index and biomass were discussed in this study.They seemed as selection criteria for making breeding strategy and target.The experiments were performed with randomized complete block design with at least three replicates in Changchun(43.53°N,125.10°E),Jilin Province in 2006-2007.Upper,middle and low layer biomass of soybean plant were measured at V₄,R₂,R₄,R₆,R₇ and R₈,respectively. After trimming 0.5m from either end,six rows were combine-harvested,and the seed was cleaned.After wind-dry,oil and protein content were measured in comfortable condition.The results were as followed:1 Changes of yield and harvest index of soybean with year of releasedSoybean yield(r=0.78^**) and harvest index(r=0.72^**) were increased liner with year of released,significantly.Yield increased 113.42%(1.38%per year) and harvest index did 19.48%(0.24%per year)from 1923 to 2005.2 The changes of biomass of soybean cultivars with year of releasedThe biomass of soybean plant increased liner with year of released at different stages, furthermore,there was significant at R₆(r=0.67^**),R₇(0.65^**) and R₈(r=0.63^**).In whole growth stage,after biomass of plant increased from emergence to R₆,furthermore,there was max at R₆, biomass begin to descend.Leaf senescence of soybean cultivars after 90s was lower cultivars before 90s.This reason was possible duce to difference of biomass of cultivars with year of released.Via relative analysis between yield and biomass,the results indicated that generative growth was the key stage of soybean yield.R₆,R₇and R₈ seemed as choosing criteria for breeding of high yield. 3 Changes of canopy yield and biomass of soybean cultivars with year of releasedYield of upper,middle and low layers increased with year of released and yield of upper layer increased significantly.The result showed that soybean yield came from upper and low layers mainly.Biomass of middle layer was more than upper and low at R₄,R₆,R₇ and R₈.Yield of middle layer was more than upper and low,the same time.Though biomass of upper layer was hardly equal to low layer,yield of upper layer was higher than low significantly.There was close relationship between yield and biomass at R₆ and R₇ specially.4 Changes of content of oil and protein of soybean seed with year of releasedIn our experiment,a l unit increase in oil content was usually accompanied by a 1.2 unit decrease in protein content.There was negatively between oil content and protein content significantly.The results showed that harvest index and biomass increased with increase of yield.There was positively between yield and some agronomic traits including biomass and harvest index. So,yield of soybean was improved via improving biomass and harvest index possibly.In this study,we included that biomass and harvest index seemed as high yield index in breeding of future.As the time,constructing reasonable canopy also was necessarily.