Combinations of nitrogen and potassium fertilization in the cultivation of cotton genotypes

In semi-arid regions, characterized by low soil fertility, it is essential to ensure an adequate proportion of nutrients to maximize cotton production, with emphasis on nitrogen and potassium, which are the main nutrients required by this crop. Therefore, the objective of the present study was to evaluate the effect of different combinations of nitrogen and potassium doses on the biomass and production components of colored cotton genotypes. The experiment was carried out in pots under field conditions, in a randomized block design, with treatments arranged in a 3 x 5 factorial scheme, with three genotypes of colored fiber cotton ('BRS Rubi', 'BRS Jade', and 'BRS Safira') and five combinations of nitrogen and potassium fertilization - N:K (50:125; 75:100; 100:100; 100:75, and 125:50% of the recommendation), with the combination of 100:100% of the recommendation corresponding to 100 mg of N and 150 mg of K 2 O kg -1 of soil, with four replicates and one plant per plot. Photosynthetic pigments, growth, and production components of colored fiber cotton genotypes were measured. The interaction between the 'BRS Rubi' genotype and the combination of 100:75% N:K fertilization promoted the highest dry mass accumulation and fiber percentage. For the production of bolls with greater weight, the 'BRS Jade' genotype stood out in comparison with the others, regardless of the fertilizer combination, while 'BRS Safira' produced greater seed weight with the 125:50% N:K fertilizer combination.