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Optimising vine management to increase yields and improve quality of Zespri® SunGold kiwifruit (Actinidia chinensis var. chinensis 'Zesy002')

Thorp, T. G., Barnett, A. M., Blattmann, M., Hedderley, D., Mayston, R.
Acta horticulturae 2018 no.1218 pp. 397-404
Actinidia chinensis, buds, canes, flowers, fruit yield, fruits, kiwifruit, pruning, summer, trays, vines, winter, wood
When summer pruning kiwifruit vines, the objective is to grow the required wood types to produce next season’s crop. The main task when winter pruning is to remove excess wood, retaining only the required number of winter buds to be able to produce the desired crop load and fruit size profile for the next season. As a general principle, it is better to select and grow smaller-diameter fruiting wood (canes) during summer, because these require less pruning, which will result in improvements in fruit yield and quality. This principle was tested with the new gold-fleshed Actinidia chinensis var. chinensis ‘Zesy002’ (marketed as Zespri® SunGold kiwifruit). Two sets of vines with either relatively small or large average cane diameters (12.7 and 13.7 mm, respectively) were established in a replicated block design, during summer pruning in year 1. Winter bud and flower numbers were adjusted on these vines in years 2 and 3 to produce vines with either standard or high crop loads. In year 2, vines with small canes and high crop load produced the equivalent of 95.0 t ha‑1 (26,394 class I trays ha‑1) compared with 77.4 t ha‑1 on vines with a standard crop load. Large cane vines produced 91.4 and 84.8 t ha‑1 on high and standard crop-load vines, respectively. Average fruit dry matter (DM) was 18.0 and 18.5% on vines with high and standard crop load, respectively. In year 3, following a mild winter, vines produced fewer flowers per winter bud than in previous years, especially on the small cane/high crop load vines. These vines produced just 75.8 t ha‑1 in year 3, a yield reduction of 20.2% compared with the previous season. Large cane/high crop load vines produced 83.8 t ha‑1 in year 3, a reduction of 8.3%. This study confirms that even relatively small changes in average cane diameter can have a significant impact on the ability of ‘Zesy002’ kiwifruit vines to produce consistently high yields.