COMPETITIVE ABILITY OF SIX COTTON CULTIVARS AND ITS IMPACT ON WEED CONTROL AND LINT YIELD

Abstract

To investigate the competitive ability of six cotton cultivars with the associated weeds, field experiment was conducted on field at Al-Ahrar / Wasit governorate, during summer season of 2004. Split plot design was used with three replications. Weed treatments as main plots included: weedy-check, weed-free, trifluralin application( 2.4 L.ha-1 ), and mechanical weed control after six weaks from sowing date, while the cultivars Cocker310, Ashor -1, Lashata, Dise, W888 and Pak-kut189 regarded as the sub-plots. Results showed different competitive ability of cotton cultivars to associated weeds. Reduction in cotton lint yield with Pak-kut189 and W888 cultivars were 21.40 and 23 % , as compared to 35.84 % with Coker310 cultivar. Similarly . Also, competitive ability of Pak-kut189 and W888 cultivar was related with height leaf area index compared with Coker310 cultivar. Cultivars with greater tolerance for weed competition showed similar responses to weed control treatments (herbicide or mechanical control) and this response reflected on their yield .Cultivars Pak-kut189 and W888 produce almost similar yield with these two treatments as compared with the weed –free treatments. On the other hand cultivars with less tolerance to weed competition showed variation in cotton yield produce in mechanical control treatment as compared with the weed – free treatment.