Effects of Boron Application on Yield, Foliar Boron Concentration, and Efficiency of Soil Boron Extracting Solutions in a Xanthic Ferralsol Cultivated with Banana in Central Amazon

Boron (B) is known to play important roles in the structures of cell walls and membranes and in the integrity and functions of membranes in plants. Under the conditions in the central Amazon region, there are few studies about this nutrient. In Brazilian soils, the hot-water B extraction method has been extensively used for evaluation of soil B status. However, difficulties with this method result in poor accuracy and precision of extraction of available B in soil. The objective of this study was to evaluate the yield, foliar concentration, and efficiency of B extracting solutions and the effect of B fertilization on B uptake in banana (Musa spp.) leaves and fruits, subgroup Cavendish (AAA), cultivated in a Xanthic Ferralsol (dystrophic Yellow Latosol) located in Amazonas State, Brazil. The experimental design was a completely randomized split plot, with four B rates (0, 4, 8, and 12 kg ha(-1)), two harvest cycles (subtreatments), and four replicates. Available B was determined with seven extractant solutions: Mehlich 1, Mehlich 3, hot water, hydrochloric acid (HCl) 0.05 mol L-1, HCl 0.1 mol L-1, HCl 5.0 mol L-1, and potassium chloride (KCl 1.0 mol L-1). The application of B fertilizer increased the yield and B concentration in leaves and fruits. Hot water and KCl 1.0 mol L-1 were the most efficient extracting solutions for the determination of available B in soil. The application of 3.4 kg B ha(-1) in the first cycle and 1.3 kg B ha(-1) in the second cycle guarantees an adequate nutritional status in banana plants.