目的 探究采前水杨酸处理延缓采后甜瓜果实后熟软化的机理。方法 以 “金甜蜜” 甜瓜为试验材料， 采用1.0 mmol/L的水杨酸溶液分别在甜瓜幼果期(花后2周)、 膨大期(花后3周)、 网纹形成期(花后4周)及采收前48 h等4个生长期进行喷施处理。甜瓜采摘后在低温下(温度为 （7±1）℃， 相对湿度为85%)贮藏， 定期测定果实硬度、 纤维素含量、 原果胶含量、 纤维素酶、 多聚半乳糖醛酸酶 （PG）、 β-葡萄糖苷酶的活性。结果 采前进行水杨酸 （1.0 mmol/L） 处理可以有效抑制甜瓜在贮藏过程中硬度和原果胶含量的下降， 减缓可溶性果胶含量的上升， 抑制PG、 纤维素酶和β-葡萄糖苷酶的活性， 有效延缓甜瓜果实的后熟软化。结论 水杨酸处理可通过抑纤维素酶、 β-葡萄糖苷酶和PG等酶的活性有效延缓果实硬度的下降， 延缓甜瓜果实的后熟软化。

The aim of this work was to study the mechanism for the delaying effect of pre-harvest salicylic acid treatment on the ripening and softening of muskmelon fruits. The "Jin tian mi" muskmelon fruit was sprayed with 1.0 mmol/ L of salicylic acid for four times at different stages: young fruit stage (2 weeks after flowering), fruit enlarging stage (3 weeks after flowering), netting stage (4 weeks after flowering) and 48 h before harvesting. The post-harvest muskmelon was stored at low temperature ((7±1) ℃, relative humidity 85 %). The fruit firmness, cellulose content, protopectin content, cellulase (Cx), polygalacturonase (PG), β-glucosidase activities related to the ripening and softening of muskmelon were determined at regular intervals during storage. The results showed that the pre-harvest salicylic acid treatment (1.0 mmol/L) could effectively inhibit the decrease of firmness and protopectin content, delay the increase of soluble pectin content, inhibit the PG, Cx, β-glucosidase activities of muskmelon during storage. The ripening and softening of muskmelon were delayed effectively. In conclusion, salicylic acid treatment significantly inhibited the PG, cellulase and β-glucosidase activities to effectively delay the decrease of the fruit firmness, and therefore delayed the ripening and softening of muskmelon fruits.