Responses of seedlings of six cotton cultivars to cotton aphid Aphis gossypii (Hem:Aphididae) under greenhouse condition

Cotton aphid is one of the most important cotton pests and causes curly and clup leaves by feeding ofhost plants sap. At first collected cotton aphids from Moghan cotton fields were confirmed, and then,reared on Varamin cultivar seedlings at 27 ± 1ocTemp., 65 ± 5% RH and LD 18:6. After three weekscotton cultivars which had been placed in a single experimental block and were at four leaf vegetativegrowth stages, were 'contaminated by two individual first-instal' nymphs of this pest. The experimentaldesign was factorial in RCBD with 6 replications.In this experiment, population density of cotton aphid delays at 4-6 and 6-8 leaf vegetation growth stages,and length of vegetative stem evaluated as quantitative response indices.In the view , point of the length of the 4-6 leaf vegetative growth stage period, the most and the leastdelay between uninfected and infected cultivars was observed respectively in Rafsanjan [followed byZeta-2] and in Sahel cultivar. T14 and Zeta-2 showed the most differences in the length of the 6-8 leafvegetative growth stage period, but Mehr and Sahel cultivars showed the least of the same. In the viewpoint of the stem length decreasing, the most effect was observed in Rafsanjan cultivar, and the least ofthis was observed in Zeta-2, Sahel and Mehr cultivars, respectively. Total evaluation of this indices inaddition to quantitative indices showed that the least responses related to susceptibility occurred in Saheland Mehr cultivars, and that the most of the same occurred in Zeta-2 cultivar.key words : Cotton aphid , Cotton cultivars seedlings , Response , Population density

کلیدواژه ها:

Cotton aphid ، Cotton cultivars seedlings ، Response ، Population density