Effect of Exogenous Calcium on Drought Resistance and Interrelated Physiological Indexes in Cotton Seedling under Drought Stress Conditions

The effect of calcium on physiological role of cotton seedling were studied under normal water and drought stress conditions by controlling the osmotic potential(adding and without 0.2 kg/L PEG-6000) and adding different Ca(NO3)2 in the solution in order to study the mechanism of exogenous calcium on drought resistance in contton seedling.The results indicated that with same Ca2+ level,under drought stress content condition,the plasma membrane permeability,O-2 production rate and malondialdehyde(MDA) and peroxidase(POD)activity were much higher than the normal water providing,while the relaive water content of leaves and the root activity were much lower than the normal water.the plasma membrane permeability,O-2 production rate,MDA and POD activity showed decreasing trend,while the relaive water content of leaves and the root activity showed an increasing trend with the Ca2+ amount increased in both normal water and drought stress conditions,but physiological role under normal water supplying was changed smaller than that under drought stress.