The Effect of Green Pruning on the Yield and Fruit Quality of the Crawling Grape Vines Cultivar Keshmeshy in the Climatic Conditions of Shirvan

Green pruning or summer pruning completes winter pruning, and it is conducted during the growing season. The purpose of green pruning is to maximize yield of high quality grapes. Green pruning in fruit trees improves light penetration and increases the quality of fruits. The objectives of this research were to determine the influence of green pruning on fruit quantitative and qualitative attributes in grapevine cultivar 'keshmeshi'. The present research was undertaken in Shirvan, Northern Khorasan province. The vines were highly uniform, 17 years old and all had equal vegetative growth strength.The planting distances were 3 × 3 m. The present study was conducted on cultivar 'Keshmeshi' that is considered to be one of the best grapevine cultivars mostly used for raisin production as well as table fresh fruits. In order to evaluate the effect of green pruning on different quantitative and qualitative attributes of fruits in cultivar "keshmeshi", the experiment was carried out in two way randomized complete block design with 12 treatments and three replications. Vines were pruned three times including full bloom, two weeks after full bloom and veraison (eight weeks after full bloom). Pruning was carried out in three levels including tipping after two, four or six nodes above the final cluster. The characteristics studied were cluster weight, berry weight, cluster length and width, berry length and width, number of cluster and berry, vine yield, leaf area, soluble solid, total acidity, pH, berry color, berry sunscald and number of shot berry. The SAS software (SAS, version 9.1) was used for statistical analysis of the recorded data. The mean comparison was performed based on Duncan's multiple range tests at %5 and %1 levels. The results of this study indicate that the severity of green pruning has no significant effect on the number and width of berries. This treatment also had no significant effect on the number of cluster. However, there were some significant effects on the TSS (P < 0.05) and on other attributes at P< 0.01.The time of green pruning had some significant effects on almost all attributes at P< 0.01 and on cluster weight, pH and berry color at P < 0.05; but it showed no significant effect on the number of clusters, TSS and TA. The results showed the reciprocal effect of treatments had a significant impact on the length and width of clusters and the length of berries, weight of clusters and berries, number of berries and shotberries, leaf area and pH (P < 0.01). The reciprocal effect of treatments caused a significant effect on the TSS and berry color at P< 0.05; but it showed no significant effect on yield, number of clusters, TAand the percentage of sunburn. The maximum length of clusters (31.47 cm) and berries (16.80 mm), width of cluster (12.98 cm), weight of cluster (344.33 g) and berry (1.85 g), number of berries/cluster (233.53) and leaf area (193.20 cm2) was observed following six-nodes pruning at verasion stage compared to other treatments. The treatment of two and four nodes at full bloom and two weeks after that, reduced the leaf area and also the rate of photosynthesis, and the amount of carbohydrates will be decreased. Subsequently yield component will be decreased. According to the result of this study, green pruning improved fruit juice quality and increased grapevine yield. Six-nodes-pruning at verasion stage did not have any negative influence on yield compared to other treatments and increased the fruit quality compared to control. Two and four nodes-pruning in full bloom decreased the yield components but increased soluble solid, pH and improved berry color.