关键词: 紫花苜蓿, 牛角花齿蓟马, 抗虫性, K, 吸收利用

Abstract: In order to explore the relationship between the alfalfa resistance to thrips and the absorption and utilization of nitrogen (N),phosphorus (P),and potassium (K) in leaves,stems and roots of alfalfa after potassium application,'Gannong No.9' alfalfa was used as the experimental materials in this experiment. The damage index of alfalfa were evaluated. The biomass of the leaves,stems and roots,and the contents of nitrogen,phosphorus and potassium in leaves,stems and roots of alfalfa were determined after the alfalfa was damaged by Odontothrips loti for 14 and 21 days under different potassium application levels (K0,K1,K2,K3,and K4).The results showed that the damage index of 'Gannong No.9' decreased significantly after potassium application (P<0.05) with the lowest at K2 level,and the biomass of the leaves,stems and roots increased significantly. The contents of phosphorus and potassium in the leaves of alfalfa increased after potassium application,while the nitrogen content decreased. The nitrogen content in the roots decreased significantly when 'Gannong No.9' was infested by O. loti for 21 days (P<0.05). The phosphorus and potassium contents of roots decreased significantly at all potassium levels except K3 and K4 levels (P<0.05),while the contents of nitrogen,phosphorus and potassium in roots increased after O. loti infected for 14 days. The nitrogen,phosphorus,and potassium absorption in leaves,stems and roots increased after alfalfa potassium application. The more biomass and more nitrogen,phosphorus and potassium absorption were distributed to the roots with the damage time going on. Potassium application increased the nitrogen,phosphorus and potassium absorption of alfalfa and regulated their reasonable distribution in alfalfa organs,which promoted the compensatory growth of alfalfa,and therefore enhanced the tolerance of alfalfa to thrips.

Key words: Alfalfa, Odontothrips loti, Insect resistance, Potassium, Absorption and utilization