中文摘要：

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。

英文摘要：

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.