Determining the effective pollination period and effects of crop load reduction on AU kiwifruit cultivars

Abstract

The objectives of this research were to determine the effective pollination period (EPP) of ‘AU Golden Sunshine’ (Actinidia chinensis) and ‘AU Fitzgerald’ (A. deliciosa), and to determine effectiveness of lateral bud or fruit removal on marketable yield of ‘AU Golden Sunshine’. For the first study, we tested the EPP of ‘AU Golden Sunshine’ and ‘AU Fitzgerald’. Flower buds were bagged one day prior to anthesis and hand pollinated either 1, 2, 3, 4, or 5 days after anthesis for ‘AU Golden Sunshine’. Flowers were hand pollinated 1, 2, 3, 4, 5, or 6 days after anthesis on ‘AU Fitzgerald. Flowers were re-bagged directly after hand pollination to prevent subsequent pollination. ‘AU Golden Sunshine’ showed no significant drop in fruit set or size within the 5-day period, and thus, appears to have an EPP ≥ 5 days after anthesis. Further testing will be performed extending the days tested. Fruit set was reduced on ‘AU Fitzgerald’ starting 5 days after anthesis. Fruit size, weight, and seed number were reduced on day 5, and the EPP of ‘AU Fitzgerald’ appeared to be 4 days for this study. The second study was conducted to determine the effects of lateral bud removal and fruit thinning on marketable yield of ‘AU Golden Sunshine’. Bud thinning treatments consisted of removing, by hand, all lateral buds and leaving only the “king” bud. Fruit thinning treatments consisted of lateral fruit removal by hand. Fruit from un-thinned vines were significantly different in soluble solids content, internal color and external color compared to both thinning treatments. Lateral bud removal resulted in the greatest total marketable yield. Total fruit yield was not significantly different amongst the three treatments, however; cull number was smallest for bud thinning. Lateral bud removal also iii resulted in the most fruit ≥ 88 g when compared to the other treatments. Marketable yield was similar among fruit thinned vines and un-thinned vines.