Abstract:

【Objective】 The present study was aimed to reveal the correlation between yield and biomass, leaf area and yield components, and to detect and map the QTLs of the yield-related traits. 【Method】 The 184 recombinant inbred lines derived from a cross between geographically and genetically distant parents, Kefeng 1 from northern China and Nannong 1138-2 from southern China, were tested in two years and then analyzed for detecting and mapping QTLs of the traits related to yield. 【Result】 A very significant positive correlation was observed between yield and above ground biomass, leaf area index, root weight, canopy width and canopy height with r values of 0.5-0.7. Seven QTLs of above ground biomass were mapped with contribution rate of 6.2%-21.1% and one QTL (qSBO-1) repeatedly detected in both years while eight QTLs of root weight mapped with contribution rate of 5.2%-20.1% and one QTL (qRTB1-1) repeatedly detected. Five QTLs of R1 leaf area index were mapped with contribution rate of 6.4%-17.2% while five QTLs of R3 leaf area index mapped with contribution rate of 7.3%-26.2% and one QTL (qLAIR3A2) repeatedly detected. Four QTLs of canopy width were mapped with contribution rate of 6.3%-13.1% and one QTL (qCWD1b-2) repeatedly detected while 11 QTLs of canopy height mapped with contribution rate of 5.2%-9.2% and four QTLs repeatedly detected. Six, two and one QTL of 100-seed weight, number of seeds per pod and number of pods per plant, respectively, were mapped with their contribution rate of 6.9%-15.7%. Five and three QTLs of number of pods on branches and number of pods on main stem, respectively, were mapped with their contribution rate of 6.3%-11.1%. Eight and three QTLs of number of nodes on main stem and effective number of branches, respectively, were mapped with their contribution rate of 4.7%-15.2%. There was one QTL shared by above ground biomass and root weight, two QTLs shared by R1 and R3 leaf area index, two QTLs by canopy width and height, one by yield and number of pods per plant, one by 100-seed weight and number of pods on branches, one by number of seeds per pod and number of nodes on main stem, and one by number of pods on branches and effective number of branches. 【Conclusion】 A total of 68 QTLs were mapped for 13 yield-related traits. Among them, only a small part was repeatedly detected in both years, implied their expression depended on years or environmental conditions. Although significant correlations existed among the traits extensively, only a small part of the QTLs was shared between the traits, which indicted different gene systems for various traits. There were few QTLs with large contribution found in the yield-related traits, thus breeding technology for pyramiding multiple genes should be considered for yield improvement.

Key words: soybean, yield, biomass, leaf trait, yield component, correlation, QTL mapping