Variation in Relation between Yield and Yield Attributes in 'Thompson Seedless' Grape and its Clones

To study variation in the relationship between yield and yield attributes in 'Thompson seedless', 'Tas-A-Ganesh' and '2A clone' vines grafted onto Dogridge ischolar_mainstock and trained on the extended Y training system, data collected from 120 vines in each variety were subjected to correlation and regression analysis. Numbers of clusters per vine was the main contributing factor for yield in all these varieties. It determined the yield by 87.9, 42.0 and 51.5%, respectively, in 'Thompson Seedless', 'Tas-A-Ganesh' and '2A clone', with the optimum number of clusters at 27.3, 43.1 and 46.5, respectively. Contrary to that in vars. Thompson Seedless and Tas-A-Ganesh, increase in number of canes was associated with higher cluster/cane ratio. Yield depended upon cluster weight in 'Thompson Seedless', mediated through number of clusters, but was not a contributory factor as evidenced by a negative correlation between clusterweight and yield. Increase in cluster weight was associated with increase in number of berries in all the varieties. Increase in berry weight was related to cluster weight in only Thompson Seedless and Tas-A-Ganesh. While berry number and berry weight together determined cluster weight by 96.3 and 92.4%, respectively, in vars. Thompson Seedless and Tas-A-ganesh, this value was just 39.0% in '2A clone'. These studies provide a clue that for realizing higher yield, cluster size needs to be greater while limiting the number of canes/vine in vars. Thompson Seedless and Tas-A-Ganesh. Increase in the number of canes would benefit '2A clone' by adopting suitable cultural practices.