The Effect of Foliar Boron Spraying on the Fruit Features of Brigitta and Legacy Highbush Blueberry (Vaccinium corymbosum) Cultivars
Boron (B) is associated with reproductive and antioxidant metabolism in plants, and in southern Chile, the deficiency of this micronutrient is ameliorated through foliar applications that are a part of agricultural management, thus ensuring the productivity of crops including highbush blueberry (Vaccinium corymbosum L.). However, the appropriate B dosage for this species is unknown, so the aim of this study was to evaluate foliar B application on fruit quality in highbush blueberry in southern Chile. During the 2014-2015 season, Brigitta and Legacy cultivars were sprayed with B at rates of 0 (control), 200, 400 and 800 mg L-1 three times (10% bloom, full bloom, and fruit set), and fruit set (%), firmness (g mm-2), soluble solids (°Brix), weight (g) and size (mm) of the fruits were determined. In addition, antioxidant activity was measured by ORAC (oxygen radical absorbance capacity) and DPPH (2,2-diphenyl-1-picrylhydrazyl). The results showed that a low rate of B (200 mg L-1) increased the fruit set and soluble solids in Brigitta, whereas Legacy required higher B concentrations (400 and 800 mg L-1). In both cultivars, firmness, fresh fruit weight, dry matter (%) and antioxidant activity increased under the 200 and 400 mg B L-1 treatments, whereas this last parameter was reduced under a high B concentration. A low B rate showed to be more effective at improving fruit quality in Brigitta, while Legacy required higher B application rates. Future research should be performed over several seasons and different cultivars to confirm these results.