Impacts of different irrigation water levels on the yield, water use efficiency, and fiber quality properties of cotton (Gossypium hirsutum L.) irrigated by drip systems

This study was conducted to determine the effects of various water deficits on the yield, water use efficiency, and fiber quality of cotton in the semiarid region of Turkey during 2017 and 2018. In the study, cotton was subjected to a number of irrigation treatments based on soil water depletion replenishment. In the T-100 (control) treatment, irrigation was performed when similar to 50% of the available soil moisture was consumed in the root zone at 1.2 m depth during irrigation periods. Cotton undergoing the control treatment received full irrigation (100% soil water). Treatments T-75, T-50, T-25, and T-00 were irrigated with 75%, 50%, 25%, and 0% of the water used in the control treatment (T-100) on the same day, respectively. According to the results, the average seasonal water use and seed cotton yield ranged from 305 to 780 mm and from 2913 to 5953 kg/ha, respectively. The presence of a water deficit significantly affected the crop yield. The highest average cotton yield was obtained with the full irrigation treatment (T-100). The average water use efficiency (WUE) varied from 0.76 to 1.06 kg/m(3) in both years. Fiber quality was influenced by the drip irrigation level in both years. The results revealed that the full irrigation treatment (T-100) could be used in semiarid climatic conditions when there is no water shortage. On the other hand, the results also demonstrated that drip irrigation of cotton with the 75% irrigation regime (T-75) had significant benefits in terms of saving irrigation water and achieving a high WUE, indicating that there is a definite advantage of implementing deficit irrigation under limited water supply conditions.