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

摘要： 为探究施K后苜蓿对N，P，K吸收利用以及苜蓿(Medicago L.)抗蓟马的影响，本试验以'甘农9号'紫花苜蓿为试验材料，于牛角花齿蓟马持续为害14 d和21 d时，评价K0，K1，K2，K3，K4水平下苜蓿的受害指数，测量苜蓿植株叶茎根生物量及N，P，K含量。结果表明：施K后，苜蓿的受害指数显著下降(P<0.05)，在K2水平最低；叶茎根生物量显著增加。施K后，叶中的P，K含量呈升高趋势，N含量呈下降趋势。蓟马为害14 d时，根中的N，P，K含量呈升高趋势；为害21 d时，根中N含量显著降低(P<0.05)，P，K含量(除K3和K4水平)显著低于K0(P<0.05)。施K后，苜蓿叶茎根中N，P，K吸收量均呈升高趋势。随着为害时间持续增加，生物量及N，P，K吸收量向根系分配量增加。K促进了苜蓿对N，P，K的吸收利用及其在各器官中的合理分配，有效提高了苜蓿的补偿生长，增强了苜蓿对蓟马的耐受性。

关键词: 紫花苜蓿, 牛角花齿蓟马, 抗虫性, K, 吸收利用