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13b. Impact of node position and bearer length on the yield components in mechanically pruned Cabernet Sauvignon (Vitis vinifera L.).

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

McLoughlin, S.J., Petrie, P.R. Dry, P.R.

Aust. J. Grape Wine Res. 17(2), 129-135; 2011.

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.