Effect of Foliar Application of Urea and Boric acid on Red Roomy Grapevines: II. The Effect on Yield and Quality of the Berries

Abstract

This investigation was conducted during the 1991, 1992, and 1993 seasons to study the effect of different concentrations and number of sprays urea and/or boric acid on yield and berries quality of Red Roomy grapevines. Two, three, four, or five sprays for both urea at 0.5% 1%, or 1.5% and /or boric acid at 0.1%, 0.2%, or 0.3% in addition to the control treatment were applied. Combined sprays of urea and boric acid was preferable in increasing the number of clusters, yield per vine, berry set parentage, fertility coefficient. weight, length and shoulder of cluster, weight and dimensions of berry, total soluble solids, total sugars, and total anthocyanins in grapes and in reducing the percentages of cracked and shot berries and the total acidity compared with the single application of both. Spraying urea at 1.0% in combined with boric acid at 0.2% four times (i.e., at growth start, first bloom, immediately after berry set, and at 30 days later) is recommended for achieving high yield and fairly good berries quality in `Red Roomy' grape vines.