T.G. Thorp, A.M. Barnett, P. Blattmann
In New Zealand, continued improvements in ‘Hayward’ kiwifruit orchard management have increased yields more than four-fold since 1975. Top performing orchards now produce 10,000 Class 1 trays/ha (36 t/ha), with some blocks producing 15,000 trays/ha (54 t/ha). We wanted to know how much further we could increase yields from this cultivar. Projects to examine this were established in 2006 using vines planted with 5.8×4.6 m spacing, providing 27 m2 of productive canopy area per vine. Vines were trained on pergola support structures with opposing female canopies (OFM); male vines were trained across female rows. During the period 2002-2006 inclusive, these vines had produced 13-15,000 trays/ha/per year. The target was to increase this to 20,000 trays per ha (72 t/ha), with the additional fruit carried on new secondary canopies trained as vertical curtains below the pergola fruiting canopies. Additional management practices included use of reflective ground covers, artificial pollination and trunk girdling. During the trial period, half the block was converted to strip males (SM); male vines were trained along alternate rows, replacing existing female vines in that row, to provide an additional 19 m2 of usable productive area per female vine canopy (46 m2 in total). Use of secondary canopies on OFM vines increased fruit yields by 3,295 trays/ha to 20,415 trays/ha (73.5 t/ha). Fruit weight (FW) and dry matter concentration (DM) decreased significantly with increasing fruit numbers per vine and vines had significant leaf yellowing and several dead leaves at commercial harvest, suggesting these vines growing on this OFM system were close to their limit in terms of economic productivity. In contrast, SM vines carrying almost twice as many fruit per plant as OFM vines, but with similar fruiting densities (fruit/m2), showed only weak relationships between high fruit number and reduced FW or DM, and the leaf canopies were still in excellent condition at commercial harvest. These results suggest that these vines growing on this SM system were not at their limit of productivity and that further increases in economic yields are possible with changes to training systems and canopy architecture.
Thorp, T.G., Barnett, A.M. and Blattmann, P. (2011). WHAT ARE THE PRODUCTIVITY LIMITS FOR 'HAYWARD' KIWIFRUIT?. Acta Hortic. 913, 419-424
DOI: 10.17660/ActaHortic.2011.913.56
Actinidia deliciosa, pruning systems, training systems, secondary canopies, strip males

Acta Horticulturae