Effect Of Exogenous Hormones On Physiological Characteristic Of Soybean At Florescence Under Drought Stress

This research is pot experiment using Suinong14as material, conducted at experimental base of Northeast Agricultural University in2010-2011. Different concentrations of exogenous hormones (abscisic acid, brassinolide) are sprayed on foliars of soybean at flowering stage under drought stress. Through analysising on osmotic adjustment substances, protective enzyme activity, endogenous hormone content, growth and yield, the effect of the ability of drought tolerance of soybean at flowering stage by spraying with different concentrations of abscisic acid and brassinolide was studied. The interaction relation between endogenous and exogenous hormone could be known and the appropriate proportion of hormone could be resolved which may provide a theoretical basis for the clear of physiological mechanisms to study technical measures to soybean drought tolerance..The important results were as follows:1. Peroxidase activity, content of malondialdehyde, soluble sugar, soluble protein, free proline, ascorbic acid, superoxide anion radical generation rate, root to shoot ratio, ABA, GA were increased, superoxide dismutase activity, chlorophyll, shoot biomass, root activity, and yields were decreased under drought conditions.2.1mg/L ABA significantly enhanced the peroxidase activity,2mg/L significantly promoting the activities of superoxide dismutase and peroxidase, as well as mitigate chlorophyll content decreased significantly,4mg/L ABA significantly enhanced the content of proline, soluble sugar and ascorbic acid,2mg/L significantly increased the soluble protein content;0.8mg/L brassinolide significantly increased the activity of peroxidase, superoxide dismutasethe,0.2mg/L significantly increased the soluble sugar content, and0.4mg/L soluble protein content increased,0.4mg/L brassinolide significantly increased content of proline and ascorbic acid content.3.1mg/L and2mg/L ABA significantly increased root biomass of soybean flowering.1mg/L exogenous ABA increased ratio of root to shoot of soybean plants; the brassinosteroid increased soybean shoot and root biomass; a certain concentration of exogenous hormones can increase root vitality under drought stress. the effect of a certain concentration of exogenous ABA on root activity better than the exogenous brassinosteroid.4.1mg/L ABA enhanced plant height,2mg/L significantly lower the soybean plant height. 1.2mg/L BR increased soybean pod number, than other treatments.1mg/L ABA on soybean the grain number per plant was significantly lower than other treatments. grain weight per plant was significantly increased by0.8mg/L brassinolide than1mg/L ABA.5. The endogenous ABA content was increased by1mg/L exogenous ABA. Content of endoge-nous ABA synthesis was decreased by0.8mg/L and1.2mg/L BR. GA content was increased by2mg/L ABA,0.8mg/L and1.2mg/L brassinolide. Endogenous cytokinin content was decreased by spraying of2mg/L exogenous ABA. Spraying0.8mg/L and1.2mg/L BR treatment increased endogenous cytokinin content.