Effect of Boron treatment on 'Bianca' and 'Gloria' pistachio cultivars

Boron is an essential element of plant growth, involved in various physiological phases, from bud break to the fruit ripens. It influences flowering (lack can cause the drop of entire flower clusters), pollen viability and production. The aim of this research was to evaluate the effects of Boron, foliar applied, in different phenological phases on the productivity of the tree and, consequently, on fruit set and nut quality. The study was carried out in Sicily, by applying the element on 'Bianca' cv and 'Gloria' selection. During flowering time (25-50% flowers bloomed), the trees of 'Bianca' were sprayed with Boron solved in water only or in sucrose solution (to favorite the pollen's receptivity on the stigma). On the selection 'Gloria', the effect of Boron applied once in May, June or July was evaluated. On Bianca's trees, the application of Boron caused an increase of fruit set and a qualitative improvement of the in shell nut and of the kernel (both fresh and dry weight). The effect was particularly evident in the trees treated with Boron which was solved in sucrose solution. Also the carpological parameters were influenced: the fruits showed statistically significant size values (width and thickness) when compared to the control, and without affecting the yield rate of kernel. Average production was increased of 37% in 'Bianca' trees treated with Boron solved in water solution. Dry leaf weight increased as well and nut splits percentage had significant reduction. On 'Gloria' selection, the treatments with Boron increased the fruit splits. Treatment applied in July caused a notable increase of production and significant increase in dry leaf weight.