RESPOSTAS DO FEIJÃO CAUPI EM FUNÇÃO DO USO DE DOSES DE POTÁSSIO

Abstract

The expansion of cowpea cultivation to the Cerrado region, especially Western Bahia, has led to the need to carry out research related to maximizing the crop's productivity. Among them, the evaluation of potassium fertilization doses is essential, since the soils in this region have low exchangeable levels of the nutrient, and have up to 85% of sand, facilitating leaching, requiring constant replacement. Thus, the objective of this study was to evaluate the response of cowpea to the use of potassium doses. The experiment was carried out in pots in a greenhouse, in a completely randomized design, with five treatments and four replications. The K doses were: T0 – (N-P-K): T0- control (20-40-00), T1- (20-40-20) (50% of the standard dose of K2O), T2- (20-40-40 ) (K2O standard dose), T3- (20-40-60) (150% of K2O standard dose), T4- (20-40-100). The analyzed variables were dry mass (DM), number of pods (NV), number of grains (NG), stem diameter (DC), weight of 100 grains (P100G), chlorophyll, total chlorophyll and SPAD index. Potassium doses did not significantly influence the DM, NV, NG, P100G and DC variables. However, the number of grains obtained a better response at the dose of 60 kg.ha-1 of K2O. The relative content of Chlorophyll A, Total Chlorophyll and SPAD Index had a sinuous behavior with the potassium doses, reaching a peak at the dose of 40 kg ha-1. With this work it is possible to highlight the importance of adequate dosage of the nutrient to supply the metabolic processes, and mainly to overcome the limitations of cultivation in the cerrado regarding potassium fertilization.