Optimization of Yield and Fiber Yield of Cotton Cultivars Under Water Regimes in the Tropical Dry Season

This study pioneers the integration of the water sensitivity coefficient (Ky) with cotton yield performance under varying water regimes in the Brazilian Cerrado. The objective was to evaluate the productive performance and fiber yield of cotton cultivars under different water regimes during the tropical dry season. The experiment followed a randomized block design in a 5 × 4 factorial scheme with four replications, totaling 80 plots. Treatments consisted of five irrigation levels based on crop evapotranspiration (25%, 50%, 75%, 100% and 125% of ETc) and four cultivars (TMG44B2RF, FM944GL, IMA5801B2RF and IMA709B2RF). Increasing water supply enhanced cotton lint yield, reaching 3209.4 kg ha−1 at the highest regime. Water regimes between 25 and 125% of the ETc significantly improved yield components, leading to an increase of up to 221% in lint yield. Fiber quality remained stable across irrigation levels and was mainly genotype-dependent. Among the cultivars, FM944GL showed high productivity and fiber yield, while IMA5801B2RF demonstrated greater water resilience (Ky = 0.73), making it suitable for water-limited environments. The findings reflect the specific conditions of the evaluated growing season. Thus, long-term studies under diverse environmental conditions are recommended to confirm these trends and enhance understanding of cotton responses to water regimes in the Cerrado.