Cotton Response to Foliar Potassium Application in South Texas Dryland

Potassium (K) deficiency is common in cotton (Gossypium hirsutum L.)-growing areas. This study aims to investigate the effects of different rates of foliar K fertilizer application on three cotton varieties: NG 5711 B3XF (V1), PHY 480 W3FE (V2), and FM 1953GLTP (V3). Potassium fertilizer was dissolved in water and was foliar-applied at 34, 50, and 67 kg ha−1. Cotton plant height (CH) and canopy width (CW) were monitored throughout the growing season. The results showed that foliar K fertilizer application significantly impacted the CH and CW in dry years. Although insignificant, the cotton lint yield increased by 15% and 20% with 34 and 50 kg ha−1 in 2020 and by 9% and 7% with 50 and 67 kg ha−1 in 2021, indicating the potential for improved lint yield with foliar K application in rainfed production systems. Similarly, variety V3 had significantly greater lint and seed yields than V1 in 2020. The average lint yield among the varieties was 32%, and the seed yield was 27% greater in 2020 than in 2021. The cotton fiber color grade was significantly greater at 50 kg ha−1 in 2020 and 67 kg ha−1 in 2021. Cotton variety significantly affected color grade, uniformity, staple length, Col, RD, and Col-b contents in 2020 and 2021. The results suggest that foliar K application can enhance cotton production in rainfed production systems. However, more research is required to quantify varietal and foliar K application rates for improved lint yield and quality.