The effect of post-sowing potassium fertilizer application on the yield and some fiber technological properties of cotton (Gossypium hirsutum L.)

This study was conducted to determine the effects of different post-sowing potassium fertilizer doses on cotton (Gossypium hirsutum L.) yield and fiber properties in Haliliye district of Şanlıurfa province in 2020-2021. The experiments were arranged in a randomized split-plot design with three replications. The Fiona cotton variety was used as plant material, and six-row plots were sown (row spacing: 75 cm, plant spacing: 5-6 cm). Main plots were defined by post-sowing days (30, 40, 50 days), while subplots consisted of potassium doses (control, 10, 20, 30 kg da-1). Results showed that seed cotton yield ranged between 396 and 520 kg da-1, with the highest yield achieved with 50 days post-sowing and 30 kg da-1 KCl application (520 kg da-1). Plant height varied from 77.95 to 85.41 cm in 2020 and from 81.13 to 87.63 cm in 2021. The highest boll weight (6.97 g) was recorded in 2021 with 50 days post-sowing and 30 kg da-1 KCl application. The number of fruiting branches and bolls per plant varied across years, with the highest boll count observed with 40 days post -sowing and 20 kg da-1 KCl application. Fiber uniformity index ranged between 82.23% and 85.40%, while short fiber content varied from 6.70% to 11.70%. As a result, potassium fertilizer doses were found to be effective in increasing cotton yield and fiber quality; in particular, the application of 30 kg da⁻¹ KCl on the 50th day gave the best results.