Abstract:
A comparison of 182 Sultana clones selected for yield showed that selection based on 9 or more years' yields on source vines was more effective than that based on 4 years. The main effect of the longer-term selection was the avoidance of leafroll-infected vines, but there may also have been a small genetic component. The leafroll, which appeared to be a mild strain, was associated with a reduction in yield of about 15%, a small increase in weight of berry, fewer bunches per vine with fewer berries per bunch, and a slight decrease in sugar concentration in the berries when adjustment was made for the effect of yield. No clones superior to those already in use were found.