Effects of potassium application on growth, yield, and quality of dryland cotton

Potassium (K) deficiency reduces cotton (Gossypium hirsutum L.) growth, development, lint yield, and fiber quality. The study's objective was to compare the effects of K fertilizer rate on cotton plant height (CPH), yield, and fiber quality in three cotton cultivars. Three cotton cultivars studied were NG 5711 B3XF (C1), PHY 480 W3FE (C2), and FM 1953GLTP (C3). Granular K fertilizer was surface broadcast and incorporated 1 week before planting at 34, 50, and 67 kg ha-1. The CPH and canopy width were measured from 30 to 105 days after planting. The cotton CPH increased by 13%, 17%, and 12% in 2020 and by 6%, 4%, and 8% in 2021 with 34, 50, and 67 kg ha-1 K fertilizer rates compared to control. The K application increased cotton canopy width by 39% in 2021 compared to 2020. The K application at 50 kg ha-1 yielded significantly more cotton yield than the control in 2020. The cotton lint yield increased by 25%, 34%, and 9% in 2020 and by 4%, 17%, and 11% in 2021 with 34, 50, and 67 kg ha-1 K fertilizer application rates than control. The cotton fiber staple length and color grade increased significantly with the 50 kg ha-1 K application rate than the control in 2020. Cultivars significantly impacted Col-Rd and Col-b in 2020 and 2021. This study shows that fertilizer-K application improves not only yield, but also staple length and color grade in rainfed cotton crops. Cotton cultivars positively responded to potassium (K) fertilization in the soil above the critical level. Potassium application resulted in greater cotton yield and quality during dry years. Cultivar FM 953GLTP responded better with K treatment. Inconsistent responses to K among cultivars warrant more studies across soils and climates.