Effects of defoliation on fruit growth, carbohydrate reserves and subsequent flowering of ‘Hayward' kiwifruit vines
2010
Cruz-Castillo, J.G. | Woolley, D.J. | Famiani, F.
A partial defoliation study was carried out on ‘Hayward' kiwifruit vines with the aim of evaluating effects on fruit yield, changes in concentration of carbohydrates, and return bloom. At full bloom, ‘Hayward' kiwifruit vines trained to the pergola system were submitted to 0% (control), 50% and 75% defoliation in the 2.0m wide central horizontal area of the canopy. This area represents the vine ‘replacement cane zone' (RCZ), whereas the remaining external area represents the ‘fruiting zone' (FZ). Removing 50% of the leaves resulted in a small (−9g in the RCZ and −3.3g in the FZ), but significant, reduction in fruit weight compared to the control vines. More severe defoliation (75%) reduced fruit weight by 13g in the RCZ and 7g in the FZ. The defoliation treatment reduced the concentrations of starch and total soluble carbohydrates (glucose+fructose+sucrose) in the shoots and starch in trunk bark compared to those in control vines. The treatments caused a large reduction in return bloom, expressed as number of flowers per winter bud, by about 25% and 53% in vines with 50% and 75% defoliation, respectively.
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