Study On Resistance Of Alfalfa To Acyrthosiphon Pisum And Its Mechanism

The experiment explores the resistance of twelve different alfalfa varieties in Ningxia Hui Autonomous Region, namely, Huangguan, Sangdeli, Bolatu, Xianxingzhe, Jingxi, WL343HQ, Gannong4, Zhongmu3,SR4030, Huanghou, MF4020, through an analysis of ratio of aphid numbers indoors and outdoors and by the method of fuzzy identification. Besides, it examines the density of leaf pubescence and the wax content of these 12 alfalfa varieties and discusses the content of soluble sugar and protein, the activities of PAL, PPO, POD, SOD, CAT, as well as the changes of tannin of alfalfa seedlings in the circumstance of 3 days,7 days and 10 days from the same density of 15 Acyrthosiphon pisum each seedling. The experiment aims to propose the criteria and assessments of the alfalfa resistance to Acyrthosiphon pisum and analyze the consequent features of different alfalfa sucked by these insects.It is initially categorized that Sangdeli, Huanghou, Huangguan, SR4030, and MF4020 have the highest resistance, then follows Xianxingzhe, Bolatu, Gannong4, Zhongmu3, and Jingxi, WL343HQ and Debao have the lowest resistance.Also, it is proved that without any external factors, the more density the leaf pubescence has, the stronger the alfalfa resistance owns, just the higher the wax content is, the stronger the alfalfa resistance possesses.In addition, it is observed that after 3 days the content of soluble sugar of alfalfa varieties descends, compared with those without exposure to Acyrthosiphon pisum; that after 7 days the content of soluble sugar ascends; and that after 10 days the content of soluble sugar Jingxi, WL343HQ and Debao, as well as Zhongmu3 ascends while the rest descends. Meanwhile, it is discovered that the content of soluble protein during different duration descends, but it has subtle difference:WL343HQ descends higher than Sandeli after 3 days, their descents show no sharp after 7 days, and the former one descends lower than Sandeli after 10 days. Therefore, the lower the content of soluble sugar is, the better the resistance of alfalfa has.Furthermore, it is detected that the activities of PAL, PPO, POD, SOD, CAT ascend during different time duration, and that the higher the activities they have, the better the resistance of alfalfa varieties owns.Last but not least, the content of tannin increases in comparison to those without any exposure to Acyrthosiphon pisum during these 10 days. And the higher the content of tannin possesses, the better the resistance of alfalfa varieties has.