Effects of saline water and N levels on eggplant (Solanum melongena L.) fruit yield, water productivity, and nitrogen use efficiency by drip and surface flood irrigation

Abstract

Due to a scarcity of freshwater resources, agriculture is dependent on the use of poor quality water for irrigation in arid and semi-arid regions. Hence, the effective use of poor quality water requires pioneering water management and nitrogen fertilizer practices for increasing yield and resource efficiency. This study aimed to investigate the effect of saline water levels, nitrogen fertilizer, and irrigation methods on eggplant yield, water productivity, NPK uptake, and nitrogen use efficiency. The experiment was conducted in 2019 and 2020 under drip (IM1) and surface flood irrigation (IM2). The treatments included three saline water levels i.e. canal water (SW1), ECiw=2.5 dS/m (SW2), and ECiw=5.0 dS/m (SW3) along with the three nitrogen levels of 75% (N1), 100% (N2), and 125% (N3) of the recommended dose of nitrogen. Application of saline water using IM1 reduced the ECe by 41.8% (SW2) and 34% (SW3) over IM2. The fruit yield, water productivity (WP), NPK uptake, and nitrogen use efficiency (NUE) was increased by 22%, 127.6%, 39.8%, 16.6%, 11.8%, and 23.8% under IM1 over IM2, respectively. A high saline water level under IM2 can cause more reduction in fruit yield, NPK uptake, and water use. Applying saline water through IM1 improves fruit yield, WP, and NUE by 13-32.8%, 104.1-147.3%, and 10.5-35.2% as compared to IM2. We found that saline water and N applied by drip improved eggplant yield, water productivity, and NPK uptake. It is concluded that irrigation water and nitrogen fertilizer consumption are optimized when saline water is applied through drip irrigation.