Effects of drought stress at different stages on soluble sugar content of soybeans

Drought is an important agricultural problem worldwide, which seriously affects the growth and yield of crops. To explore the effects of different degrees of drought on the soluble sugar content of soybeans, this study measured the soluble sugar content of two soybean cultivars at three growth stages under four levels of drought stress. The results showed that drought stress significantly affected the soluble sugar content, and there were differences among different growth stages and cultivars. At the seedling and flowering stages, the sucrose content of both Heinong44 and Heinong65 showed an unimodal trend and reached the maximum value at moderate drought. The increase rate was the highest in the leaves at the flowering stage, which increased by 36.18% and 25.79% compared with CK, respectively. The fructose and glucose contents were the highest during severe drought, and the fructose content increased the most in the leaves at the seedling stage, which increased by 18.05% and 17.67% compared with CK, respectively. The glucose content increased the most in the petioles at the flowering stage, reaching 40.66% and 35.24%. At the pod- filling stage, the three sugar contents of both Heinong44 and Heinong65 were the lowest at severe drought, and the sucrose and fructose contents decreased the most in the petioles, which decreased by 21.66% and 23.94%, 12.58% and 13.49% compared with CK, respectively. The glucose content decreased the most in the stems, which decreased by 11.72% and 9.66%. In addition, at each growth stage and drought treatment, the ratio of the soluble sugar content of Heinong44 was higher than that of Heinong65.