Nutritional diagnosis of banana (Musa AAA Simmonds subgroup Cavendish) with root sap analysis1

ABSTRACT The status of mineral nutrients in the banana crop is commonly determined by foliar and soil analyses, which often do not present a significant relation with its production performance. This study aimed to evaluate whether the root sap analysis determines the nutritional status of plants more accurately in response to fertilization. The experiment was carried out in a completely randomized design, with three treatments (complete fertilization, traditional fertilization and no fertilization), three replicates and four plants per replicate. The contents of macro (N, P, K, Ca and Mg) and micronutrients (B, Zn, Mn, Fe and Cu) were analyzed in the root sap, leaves and soil at the base of the plant. Potassium was the macronutrient found in the highest quantity in the root sap of the fertilized and unfertilized plants, while the predominant micronutrients were Mn in the fertilized plants and Fe in the unfertilized ones. The concentrations of N, P, K, Ca and Mg in the root sap were significantly lower for no fertilization than for complete and traditional fertilization, but did not show significant diferences between the foliar and soil analyses. The root sap analysis was more sensitive than leaf analysis to diagnose the nutritional status of the banana plants.