Evaluation of the effects of different water quantities and irrigation frequency on cotton yield and yield components in direct and transplanting methods

Considering the importance of cotton in crop rotation and the high reduction of cotton cultivation in recent years, it is necessary to use new approaches to increase the cultivation area, production amount and to reduce the production cost of this strategic crop. One of these strategies is the delayed cotton cultivation in the form of transplanting method by using earliness cultivars. This method can be used to plant cotton after wheat in a crop rotation and due to shortening of the growth period and without dealing with cold, an acceptable amount of crop can be obtained. Managing the time and amount of irrigation plays an important role in delayed plantings. In this regard, it is necessary to determine the optimal amount of water used by cotton in transplanting and conventional methods. This experiment was carried out in a split split plot design with three repetitions with transplanting and direct treatments as main plots, irrigation frequency including irrigation after 70, 105 and 140 mm cumulative evaporation from evaporation pan as subplot, and various water quantities including 50, 75, 100 and 125% of evaporation from the pan were considered as sub-sub plots. The results showed 38% increase of yield for transplanting method in comparison to direct cultivation, but this increase was not significant. Water use efficiency, earliness percentage and lint percentage in transplanting were 14%, 45% and 3.3% higher than direct planting, respectively. The highest yield, water use efficiency, earliness and lint percentage were related to irrigation frequency after 105 mm evaporation of the pan. The treatment of 50% of used water had higher yield, water use efficiency, and lint percentage than other treatments. Therefore, the best treatment was the transplanting method with 105 mm pan evaporation and 50% used water.