Abstract:Effect of heat shock(HS)on heat tolerance in maize seedlings and its relation to proline(Pro)were studied in this paper. The results showed that HS pretreatment at 42 ℃ for 4 h followed by a 4 h recovery at 26.5 ℃significantly increased survival percentage of maize seedlings under high temperature at 48 ℃,and the procedure of HS and recovery displayed Pro accumulation in maize seedlings. In addition,pretreatment of different concentration exogenous Pro markedly enhanced the level of endogenous Pro and the activities of antioxidant enzyme ascorbic acid peroxidase(APX),catalase(CAT),superoxide dismutase(SOD),glutathione reductase(GR)and peroxidase(POD)in maize seedlings,and improved survival percentage of maize seedlings under high temperature. These results suggested that the increase of antioxidant enzyme activities by HS induced Pro accumulation inducement could be one of the physiological basis in the formation of HS induced heat tolerance in maize seedlings.