Effects of chilling stress on chill-resistance physiological and biochemical indexes of muskmelon seedlings

In order to know the physiological reaction of chill-resistance in the leaves of different chilling-sensitive muskmelon cultivars,the normal temperature 20 ℃(controled) was taken as the comparison,under 4 ℃,6 ℃,8 ℃ low temperatures two muskmelon cultivars was forced 6 hours and under 6 ℃ being forced 2 h,4 h,6 h separately,and thus the physiological and biochemical indexes related to chill-resistance in the leaves of two different chilling-sensitive muskmelon cultivars Yujinxiang and Bailangua were investigated.The results showed that as the temperature dropped and low-temperature treatment time extended,the electric conductivity increased,the activity of superoxide dismutase(SOD),peroxidase(POD) and Catalase(CAT) raised in two cultivars,and the content of soluble protein increased.The high chilling resistant cultivar showed lower electric conductivity,higher activities of SOD,POD and CAT,and induction of more soluble protein content.When being forced 6 hours under 6 ℃,in contrast to the comparison,electric conductivity of the high chilling resistant cultivar,Yujinxiang is 69%,lower than the low chilling resistant cultivar Bailangua.When under 4 ℃ low temperature being forced 6 h,activities of CAT of Yujinxiang is 122% higher than that of the low chilling resistant cultivar Bailangua.Therefore,the chilling resistant muskmelon cultivar showed stronger stability of membrane,higher activities of protective enzyme and more content of soluble protein,thus reduced injury that the low temperature brings about to the cell.