Determination of the time of flower evocation in kiwifruit vines

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Abstract
The timing of flower evocation in kiwifruit (Actinidia deliciosa) was determined by defoliating shoots on several occasions during two growing seasons, and measuring the percentage of shoots that produced flowers in the following spring. The results obtained using this technique were not as clear as those reported for other crops, possibly because some of the axillary buds on defoliated shoots commenced growth in the current season. The effects of this regrowth on evocation are not known. Furthermore, since shoots were kept defoliated for the rest of the season, early defoliation is necessarily linked with a long period of defoliation. In view of these problems any deductions based on data obtained using the defoliation technique must be considered tentative. Our results suggest that, for most shoots in the Bay of Plenty, New Zealand, evocation occurs during December and January. However, shoots which develop late in the season may also be evoked later. Within each shoot, evocation appears to occur progressively, from the base of the shoot to the apex, and evocation of each axillary bud occurs at about the time that the subtending leaf ceases expansion. Girdling shoots in either January or March resulted in a higher budburst and c. 50% more flowers per cane in the following spring. However, covering axillary buds with aluminium foil from January to July did not reduce the percentage of shoots which produced flowers.