Effect of Carboxymethyl Chitosan on Chilling Tolerance in Cucumber Seedlings

Carboxymethyl chitosan at 0 (CK), 1/1500, 1/1000, 1/500 and 1/100 (w/v) was sprayed on cucumber seedlings on two leaves stage respectively, and then the cucumber seedlings were stressed under low temperature at 6±1℃ for 5 days, in order to study influence of carboxymethyl chitosan on chilling tolerance of the cucumber seedlings. The main results were as follows: Under low temperature stress, the cucumber seedlings sprayed with carboxymethy chitosan of favorable concentration obtained lower chilling injury index and MDA content, higher activities of protein enzyme (SOD, CAT and POD), root activity and content of Vc, soluble sugar, proline and chlorophyll compared with control. After low temperature stress, the cucumber seedlings were transferred to greenhouse for 5 days. Increase of dry matter , photosynthetic intensity and carboxlyation efficiency of the cucumber seedlings treated with favorable concentration of carboxymethyl chitosan were much higher than that of control. This fully explained that carboxymethyl chitosan in favorable concentration evidently improved chilling tolerance in cucumber seedlings.