Predicting cotton growth, pod development, and lint yield responses to irrigation and cultivar differences in Southwest Texas

In semi-arid regions, water scarcity limit root-zone water availability, restricting cotton growth and yield. Although prior studies evaluated drought responses and cultivar variations, interactions between irrigation and cultivar-specific dynamics—validated through process-based models—remain underexplored in southwest Texas. This study addresses this gap by quantifying the effects of four irrigation treatments on two cultivars, NG 4190 B3XF and ST 4990 B3XF, using field observations and DSSAT (Decision Support System for Agro-technology Transfer) CROPGRO-Cotton model. Full (100%) and moderate (75%) irrigations were based on field data, whereas half (50%) and no (0%) treatments were simulated. Key variables include phenology, pod numbers (m -2 ), pod, stem and leaf weights (all kg ha -1 ), AGB (aboveground biomass, kg ha -1 ), height (m), LAI (leaf area index), and lint yield (kg ha -1 ). Results showed that phenology varied, with differences of 5 days in anthesis, 4 in boll formation, 2 in seed set, and 5 in maturity. Lint yield varied across treatments, with MAE (mean absolute error) values of 11% and 13% for full and moderate treatments, respectively. Full irrigation maximized growth, with NG 4190 showing higher pod number (MAE 5%), pod weight (MAE 10%), and AGB (MAE 13%) than ST 4990. Half irrigation reduced pod numbers, pod weight, and AGB in both cultivars. No irrigation caused large declines in both cultivars, with MAE of 16–19% across pod number, pod weight, and AGB. Sensitivity analysis showed strong irrigation effects on boll development and AGB. Moderate irrigation sustains ~ 90% yield by preserving boll development and optimizing cotton production.