Effects of salicylic acid on physiological characteristics of cucumber under high rhizosphere temperature stress

The cucumber cultivar ' Chunqiuwang 2' was used as a test material,and the effects of 0.05 —0.20 mmol/L salicylic acid(SA) on the cucumber seedling leaves' reactive oxygen metabolism and osmoregulatory substance content were investigated at 35 ℃ rhizosphere temperature.The results showed that different-concentration SA treatments could significandy decrease the superoxide anion(O_2 ?) producing rate,malonaldehyde(MDA) content and electrolyte leakage(EL),and also significantly improve the activities of superoxide dismutase(SOD),peroxidase(POD),catalase(CAT) and the contents of proline and soluble proteins except the0.20 mmol/L SA treatment making the proline content decrease.Exogenous SA had a dosage effect on alleviating the membrane lipid peroxidation caused by high rhizosphere temperature,and 0.1 mmol/L SA has the best effect.