Influence of crop load on yield and grape quality of cv. `Chardonnay`

Abstract

In the research we tried to define proper crop load for cv. `Chardonnay` (Vitis vinifera L. cv. `Chardonnay`) trained on the 1.7 m high cordon trellis in the Vipava Valley. The experiment was designed as a block trial. Three levels of crop load were employed and inspected for their influence on yield and grape quality: normal crop load with 20-30 buds per vine, lower crop load with 20 buds and higher crop load than normal with 40 buds per vine. Bearing wood at the normal and higher than normal crop load was canes with 8-10 buds per cane and at the lower crop load longer spurs with 4-5 buds per spur. The lower crop load resulted in lower yield/vine together with higher must sugar content, its lower acids content and higher pruning weight. The extent of differences was strictly dependent on the climatic conditions in each year of the experiment. The normal crop load showed its great variability in the research results. The grape quality was quite high in all three treatments. Satisfactory must sugar content was obtained with the normal or even higher crop load. The proposed number of buds at winter pruning is approximately 40-45 buds/kg of pruning weight. Normal Ravaz index for defined conditions is between 7-10. In spite of the fact that the weather conditions in each year of the experiment appear to have had the strongest impact on the must acids content, the problem of its additional decrease should be taken into consideration when the lower crop load is applied.