The appropriate evaluation of the nutritional state of a pineapple plant and the fulfillment of its nutritional needs are important factors to improve fruit quality and production levels. This study aimed to evaluate the effect of the application of boron on its contents, distribution in the plant and fruit characteristics, in addition to discussing the range of B considered appropriate for pineapple. Boron concentration in different parts of the 'D' leaf was determined along the growth cycle of pineapple plants. The experiment was carried out in São Francisco de Itabapuana-Rio de Janeiro. The experimental design was completely randomized blocks, with 4 replicates and 5 treatments: no B application; monthly foliar sprays of borax, for 6 months before floral induction; monthly foliar sprays of borax, for 6 months after floral induction; monthly foliar sprays of borax, from 6 months before until 6 months after floral induction, and B application, in the axils of the basal leaves of the plant, at 30 days before the floral induction. Each sample consisted of five 'D' leaves, collected at 230, 300, 370, 450 and 520 days after planting. A foliar application of B determined the trend of increasing the total soluble solids content of the pineapple fruit. The weight and size of the fruit were not significantly affected by the treatments. B distribution along the 'D' leaf was not uniform. In general, the largest B concentration was observed in the apical portion of the leaf and the smallest in the non-chlorophyllated portion of the leaf. Borax foliar application increased B concentration in median and apical portions of the leaf but had no effect on basal and non-chlorophyllated portions of the leaf. The lack of symptoms of boron deficiency associated with a B concentration below the minimum limit suggests that the minimum limit is higher than the real limit of pineapple plants.
Ananas comosus var. comosus; foliar nutrition; micronutrient; adequate range of boron
