Effects Of Odontothrips Loti Damage On Growth Of Alfalfa Varieties

The paper evluatied the resistance of 8 alfalfa varieties (M8,HA-3,HA-3,Ja,ZM1,WL232,ZD and LD)to Odontothrips loti at 6-leaf-stage in lab, and studied the plant growth characteristics, including height,branch and yield damege ratio fed by O. loti.1. Evaluating on resistance of alfalfa varieties to O. lotiThe damage index of Ha-3 and M8 alfalfa were the lowest , and that of Ja was the highest, other varieties damag index were medium by infected 3, 5 and 10 adult thrips/plant respectively. The results indicated:M8 and HA-3 alfalfa were the resistant varieties to O. loti, and Ja alfalfa was the susceptible variety, the resistance of other varieties to thrips were medium. In this study the author found that the damage index of all alfalfa varieties were increasing along with thrips quantities increaing, and the plants of some varieties were dead, so ascertained that 5 thrips/plant was the fitting quantity for the study of alfalfa resistance to thrips, and established the evluation standard of alfalfa resistance to thrips at the alfalfa seedling.2. Effects of adult of O.loti thrips damages on alfalfa height and branchHA-3 alfalfa had the highest tolerance infected by 3, 5 and 10 adult thrips/plant respectively, the performance of M8 and WL232 were the higher, and Ja alfalfa had not tolerance to thrips on plant height and branch. HA-3, M8, WL232 and ZM1 alfalfa had the tolerance to O.loti for the production of alfalfa.3. Effects of nymph of thrips damage on alfalfa height and branchHA-3 alfalfa had the highest tolerance ability either in the feeding period or after 30 day removed O.loti , the performance of M8 and WL232 were the higher, and Ja alfalfa had not tolerance to thrips on plant height and branch, and other varieties were medium.4. Effects of thrips damages on alfalfa hay yieldThe hay yield of all alfalfa varieties were decreasing significantly along with thrips quantities increaing, and the linear relationship between yield and thrips quanties showed the negative correlation, the yield loss of Ja alfalfa was increased dramatically. The yield loss ratio of HA-3 was the lowest , and that of M8 was lower, and the loss ratio of Ja alfalfa was the highest, other varieties were medium infected by adult thrips and nmphy. The result indicatied that the tolerance of Ja alfalfa was the poorest, but HA-3 and M8 were the best.5.Fitting quantity for the study of alfalfa resistance to thripsThe author ascertained that 5 adult O. loti /plant was the fitting quantity for the study of alfalfa resistance to thrips through analysing the performance of the varieties height, branch and yield loss ratio infected by adult O. loti.