WATER PRODUCTIVITY AND FIBER QUALITY PARAMETERS OF DEFICIT IRRIGATED COTTON CULTIVARS IN A SEMI-ARID ENVIRONMENT

Water stress is among the abiotic stress factors that adversely affect the yield and quality of crops. In order to observe the effects of deficit irrigation on water use efficiency and fiber quality parameters of Carmen (late-maturing) and Ozbek (early-maturing) cotton cultivars, a field trial was conducted in years 2010 and 2011 at the Research and Application Farm of the Agriculture Faculty of Adnan Menderes University, Turkey. The trial was designated in randomized complete block design with three replications. Irrigation treatments were designated as full irrigation level (IL-100, which received 100 % of the soil water depletion) and those that received 75 %, 50 % and 25 % of the amount received by treatment IL-100 on the same day. The average seasonal water use varied between 331 and 774 mm according to cultivars. The highest average seed cotton yield was obtained from IL-100 treatment as averaging 6284.6 kg ha-1, followed by IL-75 treatment as averaging 5640 kg ha-1. The lowest yield was obtained from IL-25 treatment as averaging 4460.5 kg ha-1. It was determined Carmen cultivar performed higher yields than Ozbek. Average water use efficiency (WUE) values varied between 0.83 and 1.26 kg m-3. According to two-year average values, the yield response factor (ky) was found to be 0.47 for Carmen and 0.57 for Ozbek. It may be concluded that the treatment which gave the best performance whether for water saving or for high WUE was treatment IL-100 when the water was abundant. In the case of water scarcity, IL-50 treatment resulted in reasonable yield, water use efficiency and fiber quality.