THE EFFECT OF DEFICIT IRRIGATION ON YIELD, WATER STATUS, AND WATER PRODUCTIVITY OF SOYBEAN CROP UNDER DRIP IRRIGATION SYSTEM

Soybeans are very sensitive crops to environmental conditions during their growth stages. This study was conducted to determine the effect of ETc levels on canopy water content (CWC), soil water content (SWC), chlorophyll concentration, water productivity (WP), shelling, plant height, leaf area index (LAI) and soybean yield .Three water regimes (100% , 75% and 50% of estimated crop evapotranspiration, ETc) were used to subject soybean to various levels of watering regime. The average amount of irrigation water applied to treatments (100%, 75%and 50%ETc) was 1109.2, 831.9 and 554.6 mm, respectively. The obtained results showed that water stress levels had significant effects on growth characteristics and yield of soybean. The obtained results also indicated that reducing ETc from 100% to 75% and 50% caused significant decreases in all growth and yield characteristics. This study demonstrated that 100% ETc produced higher yield of soybean. The results further showed that the maximum value of grain yield was obtained when plants were irrigated with 100%ETc while the minimum values of grain yield were recorded with 50%ETc. The highest and lowest water productivity values of 1.3 and 0.59 kg/m^3 were obtained with 100% ETc and 50%ETc, respectively. Chlorophyll concentration values were higher in water stressed treatments and lower in the 100% ETc treatment.