Boron affects the yield and quality of nonirrigated pistachio (Pistacia vera L.) trees

Abstract

In Turkey, more than 95% of the pistachio (Pistacia vera L.) orchards are not irrigated. Therefore, a 4-year field trial was conducted to determine the effect of Tarimbor fertiliser (containing 18.5% boron [B]) on the yield, quality, and B content of two pistachio cultivars ('Uzun' and 'Siirt') planted under nonirrigated conditions. Tarimbor was applied to the pistachio trees as a soil application (0, 200, 400, and 600 g/tree) and a foliar spray (0%, 0.1%, 0.2%, and 0.3% w/v, using a tractor-mounted sprayer at the 'early bud break' stage and the 'fully leafed out' stage). Both the soil and foliar applications of Tarimbor had a significant effect on the pistachio yield, quality, and B content compared with the control. However, the foliar application resulted in greater improvements in the B content of leaves in both cultivars and the split nut ratio and kernel ratio in 'Uzun'. The greatest increases in yield were observed for the 0.3% foliar application for 'Uzun' (30%) and the 200 g/tree soil application for 'Siirt' (59%). In terms of quality, the application of Tarimbor appeared to have a greater effect on 'Uzun' than on 'Siirt'. No vegetative symptoms of B toxicity were observed in either cultivar when high concentrations of B were applied. Thus, Tarimbor could be used effectively as a foliar spray to enhance the B levels in the leaves of pistachio trees grown under nonirrigated conditions.