CANOPY MANAGEMENT AND DRY MATTER OF 'HAYWARD' KIWIFRUIT

Fruit dry matter is an important quality attribute within the ZESPRI-led kiwifruit supply chain. This attribute can be influenced by canopy management. The characteristics of a canopy for a single kiwifruit genotype, such as 'Hayward' (Actinidia deliciosa var. deliciosa), are influenced by environment and management. This paper uses data collected from 30 orchards dispersed over a range of elevations, within a single growing region, to assess the effect of canopy composition on fruit dry matter, fresh weight and yield. Within each orchard five canopy bays, comprising 2–4 female vines and 0–1 male vines, were sampled. Twelve canopy variables were assessed on each orchard bay about 5 weeks prior to harvest. Fruit counts were then completed on each bay and a sample of fruit collected for analysis of fruit weight and dry matter. Canopy management attributes were then related to fruit dry matter, fresh weight and yield using multivariate analysis techniques. Principal component analysis was used to reduce the dimensionality of the original canopy attributes to three key components (describing 30.1, 21.6 and 11.6% of the variation, respectively). These components described either the winter canopy management, summer canopy management or the resulting canopy density. These three orthogonal canopy components were then used to represent the axis of a cube, with each of the eight corners of the cube signifying a different canopy management style. Fruit dry matter, fruit weight and yield were assessed for each canopy management style. Results of this analysis identified two distinct canopy management styles that resulted in high yields of large fruit with high dry matter. Similarly, two management styles were found to produce low yields of small, low dry matter fruit. The remaining canopy management styles showed various advantages and disadvantages in fruit quality and productivity.