Effects of Exogenous Abscisic Acid on Physiological Characteristics in Soybean Flowering under Drought Stress

Soybean cv.Suinong 14 were pot planted in greenhouse,and different drought stress were set at flowering,then 1.0-8.0 mg·L-1 Abscisic acid(ABA)were leaf sprayed and content of superoxide dismutase(SOD),peroxidase(POD),proline,malondialdehyde(MDA),soluble sugar and chlorophyll in soybean blades under drought stress were determined 1-13 days later.The results showed that compared with normal water irrigation,POD activity,content of soluble sugar and free proline in leaves under drought conditions increased.SOD activity and chlorophyll content decreased.Exogenous ABA relieved the change of these physiological indexes under drought stress.In the test,4.0 and 3.0 mg·L-1 ABA obviously improved POD activity and proline content,respectively;1.0 mg·L-1 ABA increased the soluble sugar content and SOD activity and alleviated the decrease of leaf chlorophyll content,2.0 mg·L-1 ABA alleviated the accumulation of MDA apparently.Above results indicated that a certain concentration of ABA could effectively enhance the antioxidant capacity and slow down the senescence of soybean leaves.