Effect of Foliar Spraying with Zinc Oxide Nanoparticles on Vegetative Growth and Cluster Development of Flame Seedless Grapevine

This study was conducted during 2018 and 2019 seasons to determine the effect of foliar applications of both zinc oxide nanoparticles (ZnONPs) at concentrations of 60, 120, 240 and 480 mgL -1 , and zinc chelated at 1.5 gL -1 as well as without zinc application (control) for seven-years old Flame Seedless grapevines. The chosen vines were trellised by Spanish Parron supporting system,  grown in a clay loam soil, spaced at 2 x 3 meters apart, irrigated under surface irrigation system, and spur-pruned at  the third week of Dec. According to the results which appear that foliar applications of ZnONPs or chelated zinc enhanced vegetative growth characteristics and quality of berries. On the other hand, the increasing ZnONPs up to 480  mgL -1 reducing the most mentioned characters compared with control or convential zinc source in both seasons. Eventually, foliar spraying of ZnONPs, at rate of 240mgL ‑1 gave the highest values of total gross return, net return and beneficial cost ratio. From results of the present study, it could be recommended the foliar application of ZnONPs for Flame Seedless grapevines to improving yield quantitatively and qualitatively, thus economic return.