تأثير مستويات التسميد النتروجيني ومواعيد الإضافة على إنتاجية محصول البطيخ (Citrullus lanatus, L.) تحت نظام الري بالتنقيط Effect of Nitrogen Fertilization Levels and Application Timing on the productivity of Watermelon (Citrullus lanatus, L.) under a drip irrigation system.)

Two field experiments were conducted during the agricultural seasons (2022-2023 and 2023-2024) in the agricultural research farm in Abyan Governorate, located at a latitude of 13° 08' North and a longitude of 45° 20' East, to determine the effect of different levels of mineral nitrogen fertilizer and its application timing on the growth and yield of watermelon (Citrullus lanatus L.). The study aimed to investigate the optimum nitrogen fertilizer levels and application times to achieve the best growth and highest yield of watermelon.

A Randomized Complete Block Design (RCBD) with three replicates was used for the two experiments, which included 12 treatments resulting from the combination of four possible mineral nitrogen fertilizer levels (Urea): (0 – 100 – 200 – 300  kg N/ ha)  and three application times: The first application time (half the quantity 10 days after planting + half the quantity 25 days after planting), the second application time (half the quantity 10 days after planting + half the quantity 40 days after planting), and the third three application timings (a quarter of the quantity 10 days after planting + half the quantity 25 days after planting + a quarter of the quantity 40 days after planting).

The best results for fruit number per plant, average fruit weight, average fruit diameter, and total yield were obtained at fertilizer levels of 100 and 200 kg N/ha (compared to the control). The application schedule at 10, 25, and 40 days after planting gave the best growth and yield performance, compared with the other two application timings (10–25 days) and (10–40 days).