低温胁迫对嫁接西瓜耐冷性和活性氧清除系统的影响

研究了西瓜实生苗和以黑籽南瓜、超丰F1为砧木的嫁接苗的耐冷性及活性氧清除系统的差异．结果表明，低温胁迫下，嫁接苗的耐冷性明显高于实生苗，表现为以黑籽南瓜为砧木的嫁接苗的耐冷性>以超丰F1为砧木的嫁接苗>实生苗，此外嫁接苗和实生苗均表现为叶片中叶绿素含量下降，丙二醛(MDA)含量上升，非酶促抗氧化剂抗坏血酸(AsA)、谷胱甘肽(GSH)含量和抗氧化酶超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(AsA-POD)、脱氢抗坏血酸还原酶(DR)活性下降，说明低温逆境降低了植物体防御活性氧有关的酶促和非酶促保护系统能力，提高了体内自由基浓度，加剧了膜脂过氧化．嫁接苗的活性氧清除能力均高于自根苗，且嫁接苗中耐冷性越强的活性氧清除能力越高，说明西瓜嫁接后耐冷性的提高是与植物体内活性氧清除系统中抗氧化剂含量和抗氧化酶活性提高有关。

Effect of low temperature stress on chilling tolerance and protective system against active oxygen of grafted watermelon

This paper studied the chilling tolerance and the activity of protective system against active oxygen of own-rooted and grafted watermelon seedlings.The results showed that under low temperature stress,the chilling tolerance of the watermelon seedlings grafted on figleaf was higher than that of the seedlings grafted on Chaofeng F1,and that of the own-rooted seedlings was the lowest.The decrease of chlorophyll,ascorbate and GSH contents and superoxide dismutase,ascorbate peroxidase and dehydroascorbate reductase activities as well as the increase of MDA content in the leaves of both own-rooted and grafted watermelon seedlings indicated an injury on the protective system against active oxygen,and induced lipid peroxidation under low temperature stress.However,the activity of protective system against active oxygen was higher in grafted watermelon seedlings than in own-rooted watermelon seedlings.The activity of protective system against active oxygen in figleaf gourd-grafted watermelon seedlings with stronger chilling tolerance was higher than that of Chaofeng F1-grafted watermelon seedlings with weaker chilling tolerance.It could be concluded that the enhancement of chilling tolerance in grafted watermelon seedlings was related to the increase of antioxidants and antioxidative enzyme activities.