Effects Of Photosynthate And Mineral Elements Distribution In Alfalfa Damaged By Odontothrips Loti

Changes in N, P, K and Ca contents and photosynthate in alfalfa organs of resistant (R-1)and susceptible (I-1) varieties to thrips were measured after damaged by Odontothrips loti. Theresults are listed as follows.1. Evaluation of the resistance of alfalfa varieties and agricultural traits damdged by O. lotiDamage index of R-1and I-1increased as the increase of O. loti density; internode numbersand leaf-stem ratio for both R-1and I-1increased, while plant height, internode length, and leafarea decreased; both the damage index and dry weight loss of I-1were higher than R-1damagedby the same density. So R-1resistance and compensational growth capabilities in response to O.loti were stronger than I-1.2. Changes of the contents of mineral elements in alfalfa organs damaged by O. lotiThe N contents in R-1and I-1stem increased significantly while those in R-1and I-1leafdecreased significantly(P<0.05), the N contents in I-1root decreased firstly and then increasedwhile it decreased in R-1. The P contents in R-1stem increased firstly, and then decreased, andthe changes in P content in I-1stem were insignificant. The P contents in R-1leaf increasedconstantly under the lower density stress, and then decreased when damaged by7adults/branch,while that in I-1decreased significantly. The P contents in R-1and I-1root significantly higherthan that of the control significantly(P<0.05). The K contents in R-1and I-1increased firstly andthen decreased both in leaf and stem, whereas that of in root decreased(P<0.05). The Ca contentsin R-1stem and leaf increased significantly after infestation(P<0.05), the changes in root wereinsignificantly compared with control. The Ca contents in I-1stem decreased firstly and thenincreased, that in leaf were significantly lower than that of the control when leaf were damagedby7adults/branch, and that in root was significantly lower than that of the control.3. Changes of the contents of photosynthate in alfalfa organs damaged by O. lotiThe soluble sugar contents in R-1stem and leaf increased significantly at the lower densitystress while decreased significantly at the higher density stress; The soluble sugar contents inroot changes were insignificant when damaged by1adults/branch, then decreased significantwhen damaged by3,5,7adults/branch. The soluble sugar contents in I-1stem changes wereinsignificant at the lower density stress while decreased significantly at the higher density stress; In leaf, soluble sugar contents decreased significantly at every density; The changes in the rootwere the same as R-1, however, decrement rate were significantly lower than R-1. Changes ofsucrose and fructose were the same as the soluble sugar. The order of sugar contents in eachorgan of alfalfa was as follows: root>stem>leaf, but the sugar contents in leaf were more thanstem as alfalfa grew.