Abstract The indiscriminate and excessive application of nitrogen fertilizer, coupled with over-irrigation, represents a well-documented driver of reduced crop productivity and severe environmental degradation in agroecosystems. Although deficit drip fertigation is recognized for enhancing water and nutrient use efficiency, quantitative evidence regarding its optimal irrigation and nitrogen fertigation levels for sesame remains critically lacking. Therefore, this study was conducted to quantitatively assess the effectiveness of deficit drip irrigation regimes (I 50 : 50, I 80 : 80, and I 100 : 100% of ET c ) and nitrogen fertigation rates (N 25 : 25, N 75 : 75, and N 100 : 100% of the recommended nitrogen dose) on the morpho-physiological, agronomic, and quality attributes of sesame over two growing seasons of 2024 and 2025. ANOVA revealed that irrigation level, nitrogen fertigation rate, and their interaction had highly significant effects ( p < 0.001) on leaf number, dry weight of capsules, chlorophyll b, capsule number, and seed yield. Full irrigation (100% ET c ) substantially improved plant height, leaf number, and SPAD value of sesame. The maximum capsule dry weight and capsule number were observed under the 75% nitrogen treatment, suggesting that excessive nitrogen may promote vegetative growth at the expense of reproductive development. The application of N 100 under well-watered conditions (I 100 ) significantly enhanced chlorophyll a, chlorophyll b, and relative water content (1.98 mg·g⁻¹ FW, 0.827 mg·g⁻¹ FW, and 89.03%, respectively) compared to other treatments. Notably, the highest capsule number per plant (93.33) and 1000-seed weight (3.80 g) were documented under the interactive effects of full irrigation and a 75% nitrogen fertigation, which consequently maximized seed yield (1570.51 kg·ha⁻¹). Conversely, water stress (I 50 ) considerably reduced nitrogen and oil content, especially at 25% nitrogen fertigation, indicating a decrease in the nutritional quality of sesame seeds. Furthermore, multivariate analyses substantiated that the application of N 75 under full irrigation achieved an optimal balance among crop productivity and quality. These outcomes provide practical guidance for farmers seeking to maximize both sesame productivity and its potential profitability.
Hamoda et al. (Mon,) studied this question.