Dynamic Analysis of Biomass Accumulation and Partition in Different Yield Level Soybeans

Abstract

The objective of this study was to provide references for the dynamic control of biomass accumulation in high-yield breeding and management in soybean [ Glycine max (L.) Merr.]. The population composed of 184 recombinant inbred lines (RILs), NJRIKY, derived from a cross between Kefeng 1 (low yield and biomass) and Nannong 1138-2 (high yield and biomass) was tested in a two-year field experiment. The biomasses of below-ground and above-ground parts of plant were measured at various growing stages from 25.5 to 93.0 d after emergence, and the dynamic correlations between yield and biomasses were analyzed. The seed yield was positively correlated with the biomass accumulations of the below- and above-ground parts of soybean plants, and the peak correlation occurred at seed-filling stage (R5-R6) with correlation coefficient of 0.76 ( P < 0.01) for below-ground biomass and 0.79 ( P < 0.01) for above-ground biomass. The RILs with seed yield of 2500–2800 kg ha −1, 1760–1900 kg ha −1 and 940–950 kg ha −1 were selected to represent the high-, medium- and low-yield groups, respectively, and each group was composed of 5 RILs. The below- and above-ground biomass accumulations in the high-yield group were significantly higher than those in the medium- and low-yield groups, while the peak accumulations of below- and above-ground biomass observed at the seed-filling stage (R5) with the maximum values of 660–700 and 7200–7800 kg ha −1, respectively. The member RILs in each group was not necessary consistent in the 2 years. Those in high-yield group with yield decreased had also biomass decreased, which indicated that inadequate biomass accumulation caused by environmental changes should be the reason of phenotypic yield reduction. The dynamic partition of biomass to stem and petiole during growing stages in high-yield group (30.8% and 10.6% at R5, respectively) was significantly higher than those in medium- and low-yield groups while that to leaf and root in high-yield group (34.1% and 9.7% at R5, respectively) was significantly lower than that in medium- and low-yield groups. The results suggest that the variety development for high yield possibly depends on the comprehensive genetic improvement of both biomass and harvest index and the proper regulation of growth in soybean.