Abstract:

According to the concentration scale of oxalic acid, citric acid and malic acid in forest litter leachates of northeast China, Larix olgensis seedlings were foliar-sprayed with organic acids of different concentrations, and then subjected to low temperature (4 ℃). Effects of organic acids on physiological and biochemical characteristics of the seedlings were studied to investigate the regulation mechanism of exogenous organic acids on cold resistance of L. olgensis. The results showed that the organic acids of appropriate concentrations decreased electrolytes leakage and MDA content of the seedlings under low temperature stress. Activities of SOD, POD, APX and CAT, and concentrations of praline and soluble protein were enhanced to some extent with treatment of the acids. The chlorophyl contents were also increased. It is concluded that, exogenous organic acids could enhance the protective enzyme activity, reduce membrane lipid peroxidation, and increase osmoregulation and scavenging active oxygen abilities of L. olgensis seedlings under low temperature stress, resulting in an increase in the cold resistance of L. olgensis seedlings. The order of effects of the three organic acids on physiological and biochemical characteristics was:citric acid>malic acid>oxalic acid, and the optimum concentration of the organic acid was 5.0 mmol·L^-1.

Key words: low temperature stress, organic acids, Larix olgensis, physiological and biochemical characteristics