Effects of cane size and pruning system on shoot growth, flowering and productivity of `Hayward kiwifruit vines

The effects of cane size on axillary shoot and leaf area production, flowering, fruit yield and quality were compared on leader and conventionally pruned `Haywardʹ kiwifruit vines and canes. Two groups of canes (large and small diameter), all with similar numbers of buds, were selected: small diameter canes were terminated (extension growth had ceased early in the previous summer) and left unpruned in winter; large diameter canes were nonterminated (extension growth was continuous during the previous summer) and were pruned in winter. In the following summer, axillary shoots on these canes were either left unpruned to demonstrate their biological potential or pruned to three or six leaves past the last fruit according to conventional or leader pruning techniques, respectively. Percentage budbreak and numbers of flowers per winter bud were higher on large diameter canes compared with small diameter canes. Vine pruning system per se did not affect percentage budbreak, but leader pruning did increase the number of flowers per bud on both small and large diameter canes. Although axillary shoots on large diameter canes were longer and had greater leaf area than those on small diameter canes, this did not affect soluble solids concentrations (SSC) of ripe fruit. Leader pruning increased the SSC of ripe fruit on small diameter canes with a similar, although not significant, result for fruit on large diameter canes. Performance of these cane types is discussed in relation to the benefits of leader pruning and it is recommended that, when leader pruning, growers should select large diameter canes to ensure high vine productivity and fruit quality.