Estimation of Balance Pruning and Green Pruning on Quantitative Tratis in Table Grape (Vitis vinifera L. cv. Yaghooti) in Sistan Region

Introduction  Yaghooti grape is the earliest grape variety in Iran and is the most important horticultural product in the Sistan region, which is cultivated in more than 90% of the vineyards of this region. Considering the massive project of transferring water through pipes for 46 thousand farmer's fields as a recent approach in agricultural programs of the sistan region and also the necessity of changing the cultivation pattern, the suitable contribution of the new cultivation pattern is allocated for grape. A grapevine canopy is defined as the shoots and leaves system. Bearing and green pruning are defined as factors allows the grape farmers to enhance and maximize their production and quality. Materials and Methods  In order to evaluate the effects of balance pruning and green pruning on some traits and fruit yield of Yaghooti grape, the present research was conducted in the Zahak agricultural research station during 2017-2021.This research was conducted as a factorial experiment based on a randomized complete block design for three years. Four levels of bearing pruning intensity including: control or local custom (B1), 10 + 60 (B2), 10 + 40 (B3), and 10 + 20 (B4) considered as the first factor and four levels of intensity green pruning including; control or conventional local method (G1), pruning of cans from above eight leaves on the last cluster (G2), pruning of unproductive branches + pruning of cans from above eight leaves on the last cluster (G3), 4-pruning of branches without fruit from the bottom + pruning of unproductive branches + pruning the cans from the top of the eight leaves on the last cluster (G4) considered as the second factor in three replications. The study was conducted on 12-year-old vines of the Yaghooti cultivar, which were trained using the traditional system and spaced 3 meters apart in both directions. The data collected during cluster formation included morphological traits such as cluster length, cluster width, main and sub axes length of the cluster, berry diameter, cluster axes weight, berry weight, cluster weight, berry number in the cluster, and cluster/vine to fruit yield. The analysis of variance for each variable was performed using the PROC GLM procedure in SAS 9.4. Furthermore, the relationships between the evaluated morphological traits were determined using multiple linear regression. Results and Discussion  The results showed that bearing pruning had a significant effect on all traits except berry diameter. Green pruning had a significant effect on cluster length, total length of main and sub axes, cluster axis weight, berry weight, cluster weight, number of berries per cluster and yield. The balance pruning (20+10) caused to increase the cluster length, cluster width, berry diameter, cluster axis weight, total length of main and sub axes and berry weight by 32.5, 30.6, 8.97, 32.8, 34.4 and 15.3% compared to the control, respectively while but led to 33.8% reduction in cluster/vine compared to the control. The results of the study showed that pruning of G4 had a significant positive effect on the length and width of clusters, weight of cluster axes, total length of main and sub-axes, and berry weight, increasing them by 11%, 19.5%, 15.8%, 14.6%, and 11.9% respectively, compared to the control. The interaction between balance and green pruning had a significant effect on cluster weight, berry number in cluster, and yield. The B4G4 treatment resulted in a 137.4%, 82.3%, and 14.2% increase in cluster weight, berry number in cluster, and yield compared to the B1G1 treatment. Multiple linear regression analysis indicated that cluster length, berry weight, cluster weight, and cluster/vine were the most important traits that influenced fruit yield in the Yaghooti grape. In general, the results showed that the interaction of balance and green pruning (B4G4) increases yield by 17.2% compared the control (B1G1). Conclusion  The shape and structure of the grape vine is very effective on the growth and development of the product. This determines the amount of photosynthesis and carbohydrates production. If the structure of the grape vine is changed in such a way that a greater portion of carbohydrates production belongs to the fruit, the grape production will significantly affected in terms of quality and quantity. Due to the fact that grapes are grown by creeping method in the Sistan region, fruit and green pruning (local custom) led to a high density in the plant crown which reduces light penetration as well as the ratio of producer to the consumer leaves. This method may negatively impact the quality and marketability of grape clusters by reducing the number and weight of the clusters and berries, as well as the length and width of the clusters. However, in this study, we increased the intensity of fruiting and green pruning, which resulted in a reduced crown density and less shading. Our utilized method directed the major portion of photosynthesis to the fruit, which led to quantitative and qualitative fruit yield increment.