Effect of nitrogen on yield, quality, and irrigation water use efficiency of drip fertigated grafted watermelon (Citrullus lanatus) grown on a calcareous soil

Abstract

A two-year field experiment was conducted during the growing seasons 2016 and 2017 to investigate the response of drip fertigated watermelon to different rates of nitrogen (0, 10, 20, 30, and 40 g/m3 N) applied in the form of ammonium sulfate (AS). The combined effect of nitrogen (N) and sulfur (S) was investigated. Irrigation water use efficiency (IWUE) under the different N levels was, also, evaluated. N levels in the irrigation water induced a significant effect on yield parameters (total and commercial yields, dry matter yield, plant yield, and fruit number). Increasing the level of N also induced significant increases in fruit length and fruit fresh weight. IWUE was also significantly improved at high levels of N. Fertigation using modern techniques can be considered an efficient method in the delivery of N to the crop at N levels of 30–40 g/m3, as ammonium sulfate.