Soluble Sugar Contents, Germination, and Vigor of Soybean Seeds in Response to Drought Stress

Abstract

A greenhouse experiment was conducted to study the effect of drought stress on seed germination and vigor of soybean in relation with soluble sugars. Three drought stress treatments, well-watered treatment (WW), gradual stress (GS) imposed prior to severe stress treatment, and sudden severe stress (SS), were imposed on soybean plants at beginning seed fill stage (R5) for 20–23 d. Drought stress, whether sudden or gradual, increased the percentage (by number) of small and medium seeds compared with the well-watered treatment. In general, the small and medium seeds had lower germination than the large seeds. Drought stress reduced the germination of medium seeds compared with those from well-watered plants, but did not change the standard germination of the large seeds. The vigor of the large seeds, as indicated by germination after accelerated aging (AA) (100% RH at 42°C for 72 h), was reduced by the SS treatment compared to GS and WW treatments. Although, the GS treatment gave an advantage in AA germinati...