苜蓿斑蚜刺吸胁迫对苜蓿幼苗的生理影响

Physiological effects of piecing and sucking by Therioaphis trifolii on alfalfa seedlings

研究了苜蓿斑蚜为害苜蓿幼苗初期0～9d内，15、30头／株两个虫口密度下苜蓿幼苗植株叶绿素含量、SOD、POD、PPO等酶活性的动态变化。结果表明，在短期内苜蓿斑蚜刺吸为害使叶绿素含量明显降低，与同期对照相比差异达极显著水平（p〈0．01）；叶绿体内清除超氧阴离子自由基的SOD活性及POD活性、PPO活性均随为害时间的延长而升高，与同虫口密度对照相比差异均达极显著水平（p〈0．01）；同时，15头／株、30头／株处理植株同期内其3种酶活性明显升高，与对照相比差异分别达显著水平（p〈0．05）和极显著水平（p〈0．01），虫口密度之间差异显著（p〈0．05）。这反映出苜蓿斑蚜刺吸胁迫后使苜蓿幼苗对苜蓿斑蚜的防御能力增强。

The dynamics of chlorophyll contents and the activity of SOD, POD and PPO in alfalfa seedling leaves damaged by Therioaphis trifolii at different pest densities and in different days were studied. In 0-9 days, the chlorophyll content of alfalfa seedling leaves decreased remarkably by piecing and sucking of T. trifolii （p〈0. 01）. And the activity of SOD, POD and PPO increased remarkably with the days compared with the control （p〈0. 01）. Meanwhile, the activity of SOD, POD and PPO increased significantly （p〈0. 05） and remarkably （p〈0.01）, respectively, and significantly （p〈0. 05） between different pest densities. It suggested that the piecing and sucking of T. trifolii could strengthen the defense of alfalfa.