Cotton responses to potassium fertilization in Northeastern Brazil

Carrying out research evaluating the responses of cotton plants to potassium fertilization in different regions is of great importance, as it allows the development of recommendations for fertilization of this nutrient for the crop based on results from localized studies. Therefore, the aim of this work was to evaluate the responses of cotton plants to potassium fertilization in the climate and soil conditions of the Cariri region, located in the northeastern State of Ceará, Brazil. The experiment was conducted in an experimental area at the School of Technology (FATEC - Cariri campus), located in the city of Juazeiro do Norte, Ceará State. A completely randomized design (CRD) was adopted for statistics. The treatments were composed of a combination of five doses of potassium (0, 25, 50, 75, and 100 kg ha-1 of K2O, equivalent to 0, 50, 100, 150, and 200% of the K recommended for cotton cultivation) with four replications. At 70 days after sowing, the plants were collected. Measurements were taken of stem diameter, number of leaves, root dry matter, shoot dry matter, total dry matter, number of floral buds, number of cotton balls, and cotton ball weight. Except for the shoot dry matter and the cotton ball weight, the remaining analysed variables were significantly influenced by potassium doses. Potassium doses between 65 and 100 kg ha-1 of K2O maximized the growth, dry matter, and production components of the cotton plant in the soil and climate conditions of the Cariri region, northeastern Brazil.