Photosynthetic physiology of spur pruned and minimal pruned grapevines.
1992
Downton W.J.S. | Grant W.J.R.
Canopy development, photosynthetic performance and yield characteristics of Riesling grapevines managed by either conventional spur pruning or minimal pruning were compared or a growing season. Leaf area development 4-5 weeks after budburst was 4-5-fold greater on the minimal pruned vines due to the 6-7-fold greater number of buds that burst to produce shoots. By time of flowering (8 weeks after budburst) there was less than a 2-fold difference between the pruning treatments in leaf area per vine. At time of harvest the leaf area of spur pruned vines on a Y-shaped trellis exceeded that of minimal pruned vines. At harvest, spur pruned vines showed somewhat greater instantaneous C gain than minimal pruned vines. Calculated instantaneous water loss per vine was 2-5-fold higher for minimal pruned vines 4-5 weeks after budburst, but from flowering onwards spur pruned vines were likely to use more water than minimal pruned vines. Minimal pruned vines yielded twice the quantity of fruit of spur pruned vines, but only one-quarter the dry weight of new canes. Total C invested in fruit, new canes and leaves, however, was similar in both pruning treatments, accounting for 60-70 percent of the estimated C gain by the vines.
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