[Regulation effect of calcium and salicylic acid on defense enzyme activities in tomato leaves under sub-high temperature stress]

In order to investigate the regulation effect of Ca2+ and salicylic acid (SA) on the sub-high temperature resistance of tomato plants, the plants were treated with sub-high temperature (35 degrees C) at day time during their 1st inflorescence flowering, and CaCl2 (10 mmol x L(-1)) and SA (0.2 mmol x (L(-1 were foliar sprayed to study the variations of the activities of defense enzymes (SOD, POD, and CAT) and the content of soluble protein in tomato leaves, taking spraying clear water under 25 degrees C at day time as the control. The results showed that under the sub-high temperature stress, the SOD, CAT and POD activities in tomato leaves were decreased by 14.82%, 31.84%, and 26.34%, respectively, while spraying CaCl2 (10 mmol x L(-1)) and SA (0.2 mmol x L(-1)) decreased the leaf MDA content and increased the leaf SOD, POD and CAT activities and soluble protein content, compared with the control, indicating that Ca2+ and SA had positive regulation effect on the defense enzyme activities in tomato leaves, which could protect the photosynthetic system of tomato under the sub-high temperature stress to a certain degree.