Irrigation rate, timing, and cultivar effects on cotton yield and fiber quality

Understanding how crop yield and quality respond to irrigation timing, rates, and varietal differences is essential for optimizing water management and identifying drought-resistant cultivars. This study evaluated the effects of irrigation management on cotton yield, seasonal water use efficiency (SIWUE), and fiber quality across different cultivars. The experiment was conducted in a drip-irrigated research field in the Southern High Plains of Texas from 2020 to 2023. Three irrigation levels, including 0 mm d⁻¹ (low, L), 2.54 mm d⁻¹ (medium, M), and 5.08 mm d⁻¹ (high, H), were applied during three growth periods defined by accumulated growing degree days (GDD₁₅.₆): period 1 (P1 = emergence to 525 GDD₁₅.₆), period 2 (P2 = 525–750 GDD₁₅.₆), and period 3 (P3 = >750 GDD₁₅.₆). These combinations of irrigation rates and periods resulted in five irrigation treatments, tested across six cotton cultivars representing different maturity groups. Results indicated that reducing irrigation during early growth stages by 38 % conserved water with minimal yield reductions (2–15 %) and a 3 % increase in SIWUE, without significantly affecting fiber quality. In contrast, reducing late-season irrigation by 64 % caused substantial yield losses (16–44 %), a 16 % decline in SIWUE, and reductions in fiber quality. Cultivar differences were evident, with early to mid-maturity cultivars (e.g., DP 1822 XF, NG 3406 B2XF, and ST4595 B3XF) exhibiting higher yield, SIWUE, and fiber quality compared to cultivars from other maturity groups. These findings underscore the importance of optimizing irrigation scheduling and selecting water-stress-tolerant cultivars as practical strategies to enhance cotton productivity and water use efficiency under semi-arid conditions. • Evaluated effects of irrigation rate, timing, and cultivar on cotton yield and fiber quality over four years in semi-arid West Texas. • Early-season deficit irrigation had minimal impact on yield or fiber quality, conserving water effectively. • Full irrigation during reproductive stages was essential for maximizing cotton productivity. • Early- to mid-maturity cultivars maintained high yield and fiber quality under limited irrigation. • Results support water-saving strategies through optimized irrigation scheduling and drought-tolerant cultivar selection.