Evaluation on heat tolerance of watermelon varieties with different peel colors under high temperature stress.

【Objective】The experiment was conducted to study the heat tolerance of watermelon with different peel colors under high temperature stress in order to provide theoretical foundation for heat-resistant watermelon breeding.【Method】Field experiment was used and two treatments(closing greenhouse and the control normal greenhouse) were designed.The physiological,biochemical of leaves and quality indexes of watermelon were determined.The heat tolerance of watermelon was comprehensively evaluated by the method of membership function.【Result】Compared with the control,the total chlorophyll,MDA and proline content,and SOD activity in leaves,as well as mean fruit weight,hardness,soluble solid content,Vc content and soluble protein content of all watermelon varieties in closing greenhouse decreased in degrees.However,POD activity of all watermelon varieties in closing greenhouse increased compared with the control.CAT activity showed increase or decease in different watermelon varieties.The average of membership function in different watermelon varieties was as follows:R2R3R1R11R6.【Conclusion】The watermelon variety with obvious stripe peel had best heat resistance,followed by the watermelon with dim stripe peel and black green peel,and the heat resistances of watermelon with yellow and green peel were worse.