Effects of Exogenous Polyamines on Growth and Drought Resistance of Apple Seedlings

Effects of exogenous polyamines(Spm,Spd and Put) on growth and drought resistance of the apple seedlings under water stress were studied using pot-culture experiments simulating soil drought status.The results showed that exogenous polyamines could raise photosynthetic rate and water use efficiency(WUE),and increase the contents of organic osmotica(amino acid,proline and sugars) under middle level drought condition.The activity of SOD and CAT decreased and relative permeability of plasma membrane and content of MDA increased under middle level drought condition.However,treated with exogenous polyamines gave rise to increasing of SOD and CAT activity and decreasing of MDA content and plasma membrane relative permeability,lipid peroxidation under the drought condition,indicating that under middle level drought condition,exogenous polyamines could improve photosynthetic function,decrease lipid peroxidation and maintain normal metabolism and promote growth and enhance drought resistance of the apple seedlings.Effects of Spm was better than other 2 exogenous polyamines(Spd and Put),but no significant differences were found in 3 exogenous polyamines.