Abstract: Selection for increasing yield potential is consistantlythe main goal of soybean breeding. Plant height influences yield with uncertainty in soybean. A population of 212recombinant inbred lines (RIL) was used to analyze the correlation of dynamic plant height and its relative growth rate with yield across two-year field experiments. The results were as followed. (1) The range of yield and plant height was 1 000–5 000 kg ha^–1, 38–128 cm respectively, which indicated the sample in the study had a good representativeness. Significant differences between plant height and its relative growth rate at the same developmental stages were observed among the RILs. (2) Yield was significantly and positively correlated with plant height at 20 days after emergence, and the correlation increased with the growing stages and the highest correlation occurred when plant height culminated. Yield was positively correlated with relative growth rate in plant height at earlier growth stages and negatively correlated at later stages, indicating that faster growth in plant height at later stage would not be beneficial to higher yield. (3) A negative exponential regression mode was observed in the relationship between yield and plant height. Yield increased steeply when plant height was less than 80 cm and this trend would slow down when plant height was over 80 cm. We found yields reached 4 000 kg ha^–1 when plant heights were 70–90 cm. The merits and demerits of phenotypic analysis using RIL and how to select plant height in soybean breeding were discussed.

Key words: Soybean, Dynamic plant height, Relative growth rate, Yield, Correlation