effect of irrigation schedule on yield and its components in two cotton cultivars

due to limited water resources, applying efficient water use in agriculture is very important. this experiment was carried out in kabootarabad agricultural research station for two years using split plots in a randomized complete block design with four replications. six irrigation treatments based on evaporation from class a pan were applied as the main factor at three cotton growing stages, namely, four-leaf stage to early flowering, early flowering to early boll opening, early boll opening to the end of growing season. besides, two cotton cultivars, namely, b557 and tabladyla, were studied as the secondary factor. results showed that irrigation regimes had a significant impact on the performance in the first harvest, total yield, and ten-boll weights, but no effect was observed on the boll number per plant and the number of green plants. irrigation based on cumulative pan evaporation of 150 mm at the four-leaf stage to early flowering, irrigation after 70 mm cumulative evaporation during early flowering and early boll opening, and irrigation after 110 mm cumulative evaporation in early boll opening to the end of the growing season produced the highest cotton yield with 5113.3 kg/ha. results showed that the effects of cultivar on yield and its components were not significantly different and b557 and tabladyla both can be recommended.