Morphological and Anatomic Characteristics on Terminal Raceme Development of Soybean Varieties with Different Stem Termination Types

Stem termination is one of the most important plant type-related traits in soybean(Glycine max [L.] Merr.). In this study, two determinate soybean varieties, Zhonghuang 13(short terminal raceme) and Fengjiao 66-12(long terminal raceme), and an indeterminate variety Zhonghuang 24 were used to investigate the terminal raceme development processes through morphological and anatomic observations. Three soybean varieties were subjected to Beijing natural day(ND), 12 hours short day(SD) and 16 hours long day(LD) treatments, respectively. The results showed that the determinate varieties initiated the terminal racemes at 20–24 days after emergence, and the durations of the terminal raceme development were 12–16 days, which were earlier and longer than those of the indeterminate ones, respectively. Among the determinate varieties, Fengjiao 66-12 with longer terminal raceme initiated apical raceme earlier, and the differentiation was faster compared with Zhonghuang 13 with shorter terminal raceme. Beginning stage of the terminal raceme development in indeterminate variety Zhonghuang 24 was later, and the differentiation duration was shorter compared with determinate varieties. The beginning stage of the terminal raceme development was earlier, and the terminal raceme differentiation was accelerated under SD condition. Taken together, it indicated that photoperiod could affect the terminal raceme development of soybean.