Resposta da bananeira cv. Vitória à adubação nitrogenada e potássica na microrregião do Brejo Paraibano

Abstract

The cultivation of banana genotypes that are susceptible to Panama Disease as well as yellow and black Sigatoka, which are diseases of major economic importance in the world, predominates in northeastern Brazil and the state of Paraíba, such as the Pacovan cultivar. The Vitoria cultivar is resistant to these diseases and has the potential to replace the Pacovan cultivar. However, little is known regarding its nutritional needs and there is no fertilization management defined for this cultivar. The main management technique for banana cultivation is nitrogen and potassium fertilization, which has a direct effect on yield and fruit quality. The aim of the present study was to evaluate the effect of N and K fertilization on the growth, nutritional aspects, physiology, productivity and fruit quality of the Vitoria banana cultivar in two production cycles. The experiment was conducted from January 2016 to February 2018 in the municipality of Bananeiras (state of Paraíba, northeastern Brazil). The experimental design was a split-time plot in randomized blocks with four replications. The plot treatments consisted of two cultivation cycles (first and second production). The subplot treatments consisted of different combinations of five doses of N (15, 90, 150, 210 and 285 g plant-1) and five doses of K (24, 144, 240, 336 and 456 g plant-1) distributed using the Pan Puebla III matrix forming 10 treatments plus one control (without nitrogen and potassium fertilization). The following combinations of N and K (g plant-1) respectively defined the treatments: T1 (90; 144), T2 (90; 336), T3 (210; 144), T4 (210; 336), T5 (150; 240), T6 (15; 144), T7 (285; 336), T8 (90; 24), T9 (210; 456), T10 (15; 24). This work is structured in five chapters. The first chapter presents the General Introduction and Theoretical Reference. The second chapter presents the growth behavior of the Vitoria cultivar in response to nitrogen and potassium fertilization. The third chapter discusses the nutritional and physiological aspects of the Vitoria cultivar in response to nitrogen and potassium fertilization. The productivity and production components of the Vitoria cultivar in response to nitrogen and potassium fertilization are evaluated in the fourth chapter. Finally, the fruit quality of the Vitoria cultivar in response to nitrogen and potassium fertilization is analyzed in the fifth chapter. There was strong correlation among plant height, pseudostem diameter, days from planting to flowering, days from flowering to harvest, days from planting to harvest and specific leaf area, with greater plant height and pseudostem diameter prolonging the Vitoria banana cycle. The combination of 210 g of N plant-1 and 456 g of K2O plant-1 (N210-K456 treatment) promoted greater growth of the Vitoria banana. The leaf K content in the Vitoria banana in the first two production cycles with doses of up to 285 g plant-1 of N and 456 g plant-1 of K2O were below the sufficiency range found in the literature. With the conditions under which the experiment was carried out, the Vitoria banana plant has an efficient physiological process. Most of the production components evaluated reached their highest values with a nitrogen dose ranging from 125 to 177 g plant-1 in the first cycle and from 135 to 170 g plant-1 in the second production cycle combined with a dose of 456 g plant-1 of K2O. With combined fertilization of 134.54 g plant-1 of N and 456 g plant-1 of K2O, productivity of the Vitoria banana reached 26.27 t ha-1 (stand of 1,111 plants). The greatest firmness (32.24 N) in the fruit was achieved with 102.67 g plant-1 of N and 456 g plant-1 of K2O in the second production cycle. A combined dose of 150 g plant-1 of N and 240 g plant-1 of K2O (N150-K240 treatment) in the second production cycle led to better fruit quality of the Vitoria banana plant regarding soluble solids, soluble solids/titratable acidity ratio and firmness of fruit. In terms of quality, the Vitoria banana performed better in the second production cycle.