Effect of Foliar Boron Application on Fruit Set in 'Tombul' Hazelnut

Abstract

Fruit production in hazelnuts mainly depends on the number of female flowers that set fruit. Thus, maximizing fruit set is important. The aim of this study was to determine if fruit set could be increased by foliar boron applications in 'Tombul' hazelnut. The experiment was conducted in a grower's orchard in Ordu, in the Eastern Black Sea region of Turkey. 300 ppm and 600 ppm boron per ocak with 0.25% of non-ionic wetting agent (Tween-20) were applied with a hand gun sprayer to point of drip in the third week of May. Control ocaks received water plus wetting agent. Boron applications increased leaf boron content from 16.5% to 69.5% (300 ppm) and to 111.4% (600 ppm). In both years of study, 300 ppm was more effective than 600 ppm on fruit set. In the first year, boron applications increased fruit set by 28.6% on average. However, only 300 ppm boron treatment resulted in increased fruit set (11.5%) in the second year. The results showed that the effect of boron on fruit set varies from year to year. Boron applications did not have an effect on the number of blanks and defects, nut number per cluster or percent kernel.