Effects of foliar boron sprays on yield and nut quality of 'Segorbe' and 'Fertile de Coutard' hazelnuts

There are several reports in the scientific literature concerning the importance of foliar boron (B) sprays for the improvement of fruit set, quality and yield in some fruit species. The occurrence of blank nuts is common in hazelnut orchards, and some authors suggest that low B content is a possible cause. The aim of this work was to study the influence of B sprays on yield, nut quality and the production of blanks. A trial with two cultivars, 'Fertile de Coutard' and 'Segorbe', was carried out in the Beira Interior Region of northeastern Portugal over a 3-year period. The treatments consisted of 300, 600 and 900 mg B (.) l(-1) foliar sprays. Each B treatment was applied to separate trees on two dates: 80 and 100 days after flowering. The trees receiving the 900 mg B (.) l(-1) spray had the highest yields in both cultivars. The 600 mg B (.) l(-1) application did not significantly reduce the number of blanks, although there was a downward trend. The year of application appears to be the factor with more influence on yield and the number of blanks for both cultivars. The first application date seemed to be the more favorable, since the yield was higher for all treatment levels. 'Segorbe' had the higher yields during this study.