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. El boro (B) esta asociado al metabolismo reproductivo y antioxidante en plantas. En el sur de Chile, su deficiencia es resuelta con aplicaciones foliares de este micronutriente como parte del manejo agronomico, asegurando asi la productividad en cultivos como arandano alto ( Vaccinium corymbosum L.). Sin embargo, la informacion sobre dosis adecuadas para esta especie es escasa. Se evaluo la aplicacion foliar de B sobre parametros de calidad en fruta de arandano alto del sur de Chile. En la temporada 2014-2015, plantas de cultivares Brigitta y Legacy, fueron asperjadas con B en dosis de 0 (control), 200, 400 y 800 mg L-1 en tres momentos durante la temporada (10% floracion, plena flor y fruto cuajado), determinandose: frutos cuajados (%), firmeza (g mm-2), solidos solubles (oBrix), peso (g) y calibre (mm), ademas de la actividad antioxidante mediante ORAC (oxygen radical absorbance capacity) y DPPH (2,2-diphenyl-1-picrylhydrazyl). Una baja dosis de B (200 mg L-1) incremento la cuaja y solidos solubles en Brigitta, mientras que Legacy requirio mayores concentraciones de B (400 y 800 mg L-1). En ambos cultivares aumento la firmeza, peso fresco y seco de la fruta, asi como la actividad antioxidante al ser tratada con 200 y 400 mg B L-1, mientras en alta concentracion disminuyo este ultimo parametro. Una baja dosis de B resulto ser efectiva mejorando la calidad de la fruta en el cultivar Brigitta, mientras que Legacy requirio dosis de B mas alta. Futuras investigaciones deberian ser realizadas en diferentes temporadas y cultivares para confirmar esta tendencia.