Variability of Resistance to Alfalfa Weevil (Hypera postica Gyll.) Attack in Different Alfalfa Genotypes in Hamedan Condition

The forage yield of alfalfa (Medicago sativa L.) is reduced by the attack of alfalfa weevil (Hypera postica Gyll.) in most regions of the world, especially in Hamedan. In order to evaluate the resistance to this insect pest, 30 genotypes of alfalfa were studied in Hamedan using the completely randomized design (CRD). The results of the analysis of variance of all the studied traits showed a highly significant variability of all traits in genotypes. There was a significant difference in leaf greenness, pest damage percent, Plant height at the time of damage and percent of dry material at the level of 1% probability. This difference was significant for dry forage yield at the level of 5% probability. The results of the analysis of correlation showed a significant and positive correlation (P=0.695**) between the pest damage percent and larvae number at the level of 1% probability. In the stepwise regression for fresh forage yield, dry forage yield and dry material percent entered the model, respectively. These traits justified most of the changes in fresh forage yield with the cumulative contrast coefficient of 99.58%. Other studied traits did not have any significant influence on the model. With regard to the results of the present study, Karaj 2122 and Bami103, can be recommended as the optimum population, which are resistant to pests and suitable for cultivation in Hamedan.