Response of Fifteen Irrigated Wheat Cultivars and Advanced Lines to Thrips (Haplothrips tritici K.)

Wheat thrips, Haplothrips tritici K. (Thy.: Thripidae) is an important pest of cereals. Host plant resistance is a useful method recommended for controlling the pest. An experiment was conducted in a randomized complete block design with fifteen wheat cultivars and advanced line and four replications in two separate parts in Golpaygan area, Isfahan province during 2000-2002. One part of the experiment was sprayed four times with Fenitrothion (mlha-1) and the other part with water simultaneously. Sampling of the pest population in each plot was done through counting the number of adult thripses collected in ten sweep nets at flowering stage, and nymphs on ten ears at milky and ripening stages. At harvesting time, grain yield and TKW were also assessed. Combined analysis show no significant differences among cultivars for adult population and significant differences (p≤0.01) for nymph population. Shotor dandan and Roshan cultivars had the lowest and M-78-20 and Barekat had the highest density of nymphs (8.69, 8.73, 20.9 and 19.71 nymph/ spike, respectively) and showed significant differences with other cultivars. Barekat cultivar, in spite of its high density of nymph/spike, had the lowest SSI for TKW, percentage of TKW loss and grain yield loss. Pishtaz cultivar having the highest quantity of mentioned factors was the most susceptible cultivar. Differences between sprayed and non-sprayed parts for yield were not significant but for TKW was significant (p≤0.01)