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本试验以“吉农十二”甜瓜幼苗为试验材料,于三叶一心时,叶面喷施不同浓度水杨酸(SA),对低温弱光下甜瓜幼苗抗氧化酶活性及光合特性进行测定.结果表明:胁迫前用1.0 mmol/L和1.5 mmol/L SA预处理幼苗,其叶片的超氧化物歧化酶(SOD)活性在处理后第4天极显著高于CK(清水处理),过氧化物酶(POD)活性在处理后第3天极显著高于CK,过氧化氢酶(CAT)活性在处理后第2天极显著高于CK,各处理的丙二醛(MDA)含量均低于CK.不同处理对光合特性指标的影响表现为:胁迫前用1.0 mmol/L和1.5mmol/L SA预处理幼苗的光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Gs)均高于CK,胞间CO2浓度低于CK.当SA预处理浓度为2 mmol/L时,除Ci和MDA高于CK外,其它指标均低于CK,表现出抑制作用.表明适宜浓度的SA可有效调控低温弱光胁迫下甜瓜幼苗叶片的保护酶活性及光合性能,有效缓解低温弱光胁迫对甜瓜幼苗的伤害,提高了幼苗低温弱光耐性,其适宜浓度为1.0 mmol/L和1.5 mmol/L.“,”The seedlings of melon “Jinong 12” under low temperature and poor light were foliar-sprayed with different concentration of SA, then the leaf physiological characteristics and antioxidant enzyme activities were measured. The results showed that foliar spraying of 1. 0 mmol/L and 1. 5 mmol/L of SA before the stress, the leaf activities of superoxide dismutase (SOD) activity after 4 days, peroxidase (POD) activity after 3 days and catalase (CAT) activity after 2 days significantly increased, the leaf photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr) increased compared with CK (water treatment), while the heintercellular CO2 concentration (Ci) and malondialdehyde (MDA) content decreased. However, in treatment of foliar spray of 2. 0 mmol/L of SA before the stress, Ci and MDA increased, while other indexes decreased compared with CK. All of these results suggested that SA could regulate the leaf photosynthetic functions of melon seedlings, and enhance the seedlings resistance against low temperature and poor light. The optimum concentration of SA for the foliar spraying was1. 0 mmol/L and 1. 5 mmol/L.