Effects of Cluster Thinning and Cane Topping on Balanced Yield and Fruit Quality of Table Grape (Vitis vinifera L.) cv. Askari

Overcroping, shading and short growing season can reduce the pool of carbohydrate reserves, and consequently reduce the quality of crop in grapevines. An experiment was conducted in order to study the effects of cluster number and different levels of cane topping on balanced yield and qualitative traits of table grape (Vitis vinifera L.) cv. Askari. The design of experiment was factorial in completely randomized blocks with four replications. Factors included cluster number (Control, 25, 30, 35, 40, 45 and 50 cluster per vine) and cane topping included (Control, removal 1/4, 1/3 and 1/2 length of shoot). Results showed that decreasing the number of cluster to 25-35 per vine, significantly increased %TSS, TSS/TA and pH but with increasing cluster number, these traits were significantly reduced. Thinning treatment to 25 cluster showed significant difference from the viewpoint of %TA compared with untreated control. Also topping treatment significantly increased %TSS, %TA, TSS/TA ratio and decreased % TA compared with untreated control. Reducing the cluster to 25-45 per vine significantly increased cluster weight, however, no significant difference was observed between control and 50 clusters per vine and/or 25 to 50 clusters. Yield per vine was reduced in all treatments in comparison with untreated control. However, no difference was shown between 25 to 35 and or 40 and 50 clusters per vine. According to the results obtained, cluster thinning combined with topping can be recommended for increasing fruit quality and balanced yield of Askari table grapes in cold climate of Cisakht region.