Impact of node position and bearer length on the yield components in mechanically pruned Cabernet Sauvignon (Vitis vinifera L.)

Abstract

Background and Aims: Bunch number per node or shoot varies significantly between seasons and is a major cause of yield variation. Varying total node numbers by pruning is the least expensive way to regulate yield. However, there is little information available on how varying bearer length (and thus node number) in a machine-pruned canopy alters yield components. Methods and Results: The impact of bearer length on yield components was investigated in a mechanically pruned vineyard in Coonawarra, South Australia. Yield components were analysed according to the node position on the bearer at which the shoot arose. Both budburst and inflorescence number per node were highest at the distal node positions regardless of bearer length. When node positions two and three were located in the two most distal nodes made terminal by the pruning, they were significantly more fruitful than equivalent nodes on longer bearers. Shoots that arose from the two most distal node positions had the highest flower number per inflorescence and berry number per bunch. Conclusions: Budburst, and the number and size of the inflorescence and bunch were affected more by the node position at which the shoot occurred relative to the cut end of the bearer, than the position of the node from the base of the bearer. Significance of the Study: Our understanding of how pruning regimes impact on yield and how these pruning regimes may be modified to achieve a target yield has been improved. © 2011 Australian Society of Viticulture and Oenology Inc.