Response of Chlorophyll Fluorescence to Drought Stress at Flowering in Different Soybeans

Known as the rapid non-destructive probe for studying plant photosynthesis,chlorophyll fluorescence analysis has been gradually put into use in studying the effects of stressful environments on plant photosynthesis.To investigate the effect of drought stress at flowering on chlorophyll fluorescence characters of soybean,three soybean genotypes were adopted,and the change of the chlorophyll fluorescence parameters were determined by using OS52FL chlorophyll fluorometer.Under the condition of drought at flowering,the ratio of the variable to maximum fluorescence(Fv/Fm);the ratio to of variable to minimal fluorescencet (Fv/F0) and non-photochemical quenching coefficient (NPQ) decreased,while the electron transport rate(ETR) increased.The analysis indicated that photosystem II damaged,and primary light energy conversion of PSⅡ(Fv/Fm),potential activities of PSⅡ(Fv/F0) and heat disseminate which possess photoprotective effect were decreased and photosynthetic electron transport increased,and the chlorophyll fluorescence parameters were closely correlated with each other.The change of chlorophyll fluorescence parameters under drought stress at flowering varied with genotypes,and the damage of photosynthetic apparatus of Xindadou 1 was lighter,so more light energy absorbed by Xindadou 1 was converted into chemical energy and the ability of drought tolerance was stronger.Therefore,it is possible to determine the drought resistance in soybean using chlorophyll fluorescence characters.