Effects of leader pruning on vine architecture, productivity and fruit quality in kiwifruit (Actinidia deliciosa cv. Hayward)

The effects of two summer pruning strategies on vine architecture, fruit yield and quality were compared over three growing seasons. With 'leader pruning', all vigorous vegetative shoot growth close to the central leader zone was removed continually through the growing season. With 'conventional pruning', this new shoot growth was left virtually un-pruned over summer with only summer pruning to shorten fruiting laterals in the fruiting zone to three to four leaves past the last fruit. Leader pruning resulted in significant increases in the ratio of second year wood to first year wood, and in the number of self-terminating canes per vine. The basal diameter of canes was significantly reduced in leader pruned vines. Leader pruning was associated with an increase in total fruit yield. This increase was a result of increased fruit size on leader pruned vines, coupled with a small increase in the number of fruits per unit area. The number of winter buds per square metre did not differ from that of control vines, suggesting that the slight increases in fruit number could be attributed to an increased number of flowers per winter bud. Changes in vine composition as a result of leader pruning included a decrease in leaf number, particularly in the upper zone of the canopy, and these changes were associated with significant changes in fruit quality, with fruits from the upper zones being larger, and having a higher soluble solids content after storage than fruits from lower parts of the vines in the same treatment. The effects of pruning strategy on vine resource balance allocation are discussed. (C) 2001 Elsevier Science B.V. All rights reserved.