Caffeic acid and calcium application affects electrolyte leakage, hydrolases and cytosolute contents of heat stressed cotton seedlings

摘要

Cotton (Gossypium arboreum L.) genotypes viz., LD 694 and LD 327 were sown in pots. The foliar application of caffeic acid (CA) and CaCl_2 (Ca~(2+)) (@ 10 and 20 mg/1) was given on fifth day followed by heat stress (42±2°C) treatment to six day oldseedlings for five hours. Heat stress significantly increased per cent electrolyte leakage in cotyledonary leaves of both genotypes. CA application significantly decreased electrolyte leakage under stress whereas Ca~(2+) application had non significant effect. Foliar application of Ca~(2+) and CA did not alter contents of amino acids in LD 694 and LD 327 seedlings under control. In heat stressed sets contents of free amino acids were significantly decreased by Ca~(2+) and CA application. Starch contentwas comparable under control and heat stressed genotypes and Ca~(2+) and CA treatments had negligible effect. Total soluble sugar accumulation was not affected by Ca~(2+) and CA application in control. The content of soluble sugar was recorded more understress and Ca~(2+) application further increased their accumulation. The enzyme activities of both a- and b-amylase were increased after heat stress. Both Ca~(2+) and CA treatments had promotory effect on activities of these enzymes under heat stress that lead to more accumulation of cytosolutes that helped them to withstand stress.