Boron (B) is normally applied at Brazilian apple orchards, but without any regional experimental support. The aim of this study was to evaluate the effect of forms of B addition on apple yield and quality. The experiment was set up in São Joaquim, Southern of Brazil, using two apple cultivars (Imperial Gala and Fuji Suprema). Treatments consisted of a factorial combination of rates of B applied to the soil, biannually, and time of B sprayed to the plants, annually, from 2002. It was used a randomized block with treatments arranged in a split-plot design. Boron sprays were allocated in the main plots (only water or acid boric solutions applied at 0.3% at the pink stage or at 0.6% just after harvest) and rates of soil B (0, 2.5 and 5.0 kg ha-1 of B as borax) were allocated in the split-plots. Determinations were performed in the seasons of 2009/2010 and 2010/2011. Application of B to the soil was more effective than foliar B sprays for increasing B concentration inthe fruits, leaves and in the soil, however it did not affect any of the fruit attributes related to the physiological quality, regardless of cultivar. Foliar B sprays decreased starch content and titratable acidity, and did not affect soluble solids content and flesh firmness. Sprays of B applied at bloom decreased pollen grain germination in 'Imperial Gala' and fruit set in 'Fuji Suprema'. Fruit yield was not affected by the application of B, regardless of time, form or rate in any cultivar. Thus, there is no need to apply B in orchards containing these cultivars when grown in high organic matter soils in order to increase yield or fruit quality.
Foliar fertilization; fruit composition; fruit maturity; apple cultivars
