The evaluate of growth, yield and physiological responses of bitter apple (Citrullus colocynthis) under deficit irrigation stress condition

To evaluate the effect of deficit irrigation stress on growth, yield and physiological traits of bitter apple (Citrullus colocynthis), the experiment was conducted with three replications. Irrigation levels were 100% ETc and two deficit irrigation 70% and 50% ETc. The results showed that deficit irrigation stress significantly reduced growth and fruit yield. The lowest leaf area, plant length, fruit number per plant and fruit yield was obtained in deficit irrigation 50% ETc. Relative water content and chlorophyll content significantly decreased in response to increase in deficit irrigation stress. The increase in deficit irrigation stress resulted in higher peroxidase activity, electrolyte leakage and proline accumulation, although there was no significant difference between irrigation 100 and 70% ETc. Deficit irrigation 70% ETc saved 30% of irrigation water with a 15.5% reduction in fruit yield, so caused 16.8% increase in water use efficiency. Therefore, under limited irrigation water, it is recommended to irrigate bitter apple plants at 70% ETc irrigation to produce not only the same yields, approximately, but also to save more of water as compared to 100% ETc treatment.