中文摘要：

采用1 g/L的壳聚糖分别在“银帝”甜瓜（Cucumis melo L.）开花前1周、幼果期、果实膨大期、网纹形成期对植株进行喷洒.结果表明,采前壳聚糖处理可有效提高甜瓜果实采后相关防御性酶的活性.随着处理次数的增加,多酚氧化酶（pPO）、几丁质酶（CHT）活性先上升后下降.病程相关蛋白β-1,3-葡聚糖酶（GLU）活性增加,过氧化物酶（POD）、苯丙氨酸解氨酶（PAL）活性提高,总的看来,以累积处理4次的甜瓜果实防御性酶活性增加较为明显.

英文摘要：

Plants of muskmelon （cv.Yindi） were sprayed with chitosan at 1 g/L separately at one week before flower,young fruit period,fruit enlarging period and netting period.Results showed that preharvest chitosan treatment improved the activity of defensive-related enzymes of muskmelons.With the increase of the spray times,the activity of polyphenoloxidase（PPO）,peroxidase （POD）,phenylalanine ammonialyase（PAL） were enhanced,pathogenesis-related protein β-1,3-glucanase （GLU） and chitinase （CHT） activities were improved as well.The four times cumulation of spraying had the most obvious effect on the increase of the muskmelons activity of defensive-related enzymes.