上海青遭受小菜蛾取食为害后 ,0 .5小时内叶片的超氧化物歧化酶 (SOD)、过氧化氢酶 (CAT)、过氧化物酶 (POD)、多酚氧化酶 (PPO)和总酚含量发生变化。就一天内的变化趋势而言 ,受害叶片的SOD、CAT、POD、PPO活力和总酚含量总体上比正常叶片低。但在 1 5:0 0时 ,正常叶片的SOD、CAT和POD活力最低时 ,受害叶片这三种酶的活力却明显上升 ;在 1 1 :0 0时 ,正常叶片的PPO活力为最低值时 ,受害叶片的PPO活力却上升至最高。这可能是由于小菜蛾取食对叶片的过度胁迫造成的结果。正常叶片的PPO活力与总酚量为负相关 ,但受害叶片没有这种关系 ,可见小菜蛾取食还引起了青菜生理的紊乱。受害植株的未受害叶的酶活力也不同程度地发生变化 ,可见上海青对小菜蛾的取食胁迫的应激生理反应是系统性的。总而言之 ,当上海青的直接防御体系被小菜蛾破坏时 ,上海青可能有其它防御小菜蛾的机制 After suffering from the infestation of P. xylostella in Shanghai Green, SOD, CAT, POD and PPO in 0.5 h were Total phenol content changes. In terms of the trend within a day, the SOD, CAT, POD, PPO activities and total phenolic content of the affected leaves were generally lower than those of the normal leaves. However, when SOD, CAT and POD activities of normal leaves were lowest at 15:00, the activity of these three enzymes in the injured leaves increased obviously. At the 1: 0 0:00, the activity of PPO in normal leaves was the lowest , PPO vitality of injured leaves increased to the highest. This may be the result of over-stress on the leaf by Plutella xylostella feeding. The PPO activity of normal leaves was negatively correlated with the total phenolics, but the diseased leaves had no such relationship. Therefore, the feeding on Plutella xylostella also caused the physiological disturbance of vegetables. The virulence of unharmed leaves of the affected plants also varied to varying degrees. It can be seen that the stress physiological responses of P. xylostella to feeding on Plutella xylostella were systematic. All in all, when Shanghai Blue’s direct defense system is destroyed by diamondback moth, Shanghai Green may have other mechanisms to prevent diamondback moth