Effect of Boron Fertilization on Vigor, Yielding and Fruit Quality of ‘jersey’ Highbush Blueberry

The aim of the study was to examine response of ‘Jersey’ highbush blueberry to boron (B) fertilization. The experiment was carried out in 2002-2003 at a private plantation in Central Poland on mature blueberries planted on a sandy loam soil with pH 4.1, low organic matter status, and medium available B content. Blueberries were supplied with B by foliar applications or broadcasting. Foliar B sprays were done in the spring or the fall. Spring B sprays were performed at the beginning of blooming, at petal fall, and 3 and 6 weeks after the ending of flowering. In each spring spray treatment, B was used at a rate of 0.2 kg ha. Fall B spray was done 5 weeks after fruit harvest using 0.8 kg B ha. Soil B was applied at the stage of bud break at a rate of 2 kg ha. Blueberries unfertilized with B served as control. The results showed that soil B application and spring B sprays increased B status in flowers and leaves. However, B fertilization, regardless of application mode, had no effect on plant vigor, the number of flowers per cane, fruit set, mean fruit weight, berry firmness, and yielding. Berries of blueberries sprayed with B in the spring had increased soluble solids concentrations. It is concluded that: (i) B fertilizer requirements of ‘Jersey’ highbush blueberry are low, and (ii) at hot water extractable B concentration in a soil below 0.37 mg kg and/or at B status in leaves of current season shoots below 37 mg kg, spring B sprays should be applied in blueberry culture to increase soluble solids concentration in fruit.