Ecofisiologia e lucratividade da bananeira sob fertirrigação nitrogenada e potássica.

Abstract

Aiming to evaluate the effects of N and K applied through irrigation water in soil attributes and physiological, yield and economical aspects of banana, a 4x4 factorial experiment in randomized blocks, was carried out in the coastal tablelands, at Sergipe Federal University Experimental Station. Doses of N and K2O were (0; 350; 700 e 1050, kg ha-1 year -1, as urea) and (0; 400; 800 e 1200, kg ha-1 year -1, as potassium chloride) respectively. Soil pH, organic matter, K, Ca and Mg content, plant height, pseudostem diameter, leaf area, ratio and specific leaf area, energy partition and conversion and yield components, such number of hands and fruits per bunch number of fruits per hands and bunch weight, chlorophyll and gas exchange were obtained and calculated. An economical analysis also was accomplished. Nitrogen and K had a significant influence on soil attributes, banana growth and yield. Leaf nitrogen and potassium critical levels were 33.11g kg-1 and 22.13g kg-1 which were associated with the application of 632.39 kg of N ha-1 and 700kg ha-1 de K2O respectively. Leaf P and Ca contents increased and Mg decreased as N doses increased. Calcium and Mg leaf content decreased as K2O doses increased. Maximum chlorophyll concentration was 6.69mg dm-2 at 478kg ha-1 of N. Reduction of stomata conductance was observed mainly at 700kg of N ha-1 in the absence of K and it affected the photosynthesis process. Banana yield of 32.65t ha-1 was associated with 1050kg of N ha-1 and 1112kg ha-1 of K2O with an economical return of 27.75% at a benefit/cost relationship of R$1.38.