Effects of different numbers of buds per unit trunk cross-section area on growth, yield and quality in the 'prima' grape (VITIS VINIFERA L.) cultivar

In this study, the effects of varying numbers of winter buds left per trunk unit cross-section area were observed in the Prima grape variety. The treatments were determined by the trunk cross-section areas of vines as 2.0 bud.cm-2, 2.5 bud.cm-2, 3.0 bud.cm-2, 3.5 bud.cm-2, and 4.0 bud.cm-2. The control vines were left as 20 buds for the initial 500 g of cane weight and 10 buds for every subsequent 500 g. The effects of the treatments on certain phenological and physiological characteristics, as well as vegetative development, grape yield, and quality, were researched in the vines. It was determined that the bud burst percentage and the coefficient of bud fertility in the vines were reduced as the number of buds increased (14-32 buds). There was no significant change between the treatments in terms of their numbers of water sprouts and shoots arising from secondary dormant buds. It was determined that the increase in the number of buds left on the vine caused an increase in the number of shoots up to a certain level, and this effect reduced shoot length and shoot diameter development. No significant difference was determined in leaf N, P, K contents or chlorophyll measurements. Grape yield was higher than 3.5 tons in the treatments of 3.0 buds, 3.5 buds, and 4.0 buds per cm2. During the study, no significant difference was observed between the treatments in terms of cluster properties, berry properties (except for berry size), and berry color, or TSS and pH contents in juice. Increased numbers of buds in the study led to an increase in yield, without causing a significant loss in quality, except for the control treatment. According to the results of this study, the recommended number of buds to be left per trunk unit cross-section area, in addition to yield and quality, crop load, which can be recommended with minimal need for summer pruning in terms of vegetative balance, is 3.0 bud.cm-2. (author)