COMPARISON OF DIFFERENT FERTILISER TYPES APPLIED TO 'HAYWARD' KIWIFRUIT

Several relationships have been reported between 'Hayward' kiwifruit storage quality and nutrient status, particularly calcium (Ca) and nitrogen (N). Experiments in the Bay of Plenty over two seasons examined whether applications of NitraBor™ fertiliser, a solid fertiliser product containing calcium nitrate and boron (B), applied during the early fruit development stage, could influence fruit quality at harvest. Part 1 of this project commenced in spring 2003 when two rates of NitraBor™ were applied under vines in spring. These applications were additional to the standard fertiliser programme used in the orchard. Vines treated with NitraBor™ had increased fruit weight and increased fruit dry matter at the higher application level. NitraBor™ application did not significantly increase fruit concentrations of Ca, magnesium (Mg), potassium (K), and phosphorus (P) at harvest. Part 2 of this project was set up in spring 2004 to compare the effects of two fertiliser treatments on fruit, leaf and soil attributes. The two treatments were NitraBor™ and Calcium Ammonium Nitrate (CAN, the standard N fertiliser input on this orchard); both were applied under vines. Soil base saturation and Ca, Mg, B and zinc (Zn) concentrations significantly increased in the NitraBor™ plots, compared with those plots where CAN was applied. There were no significant differences in leaf nutrient concentrations between treatments, except for leaf Zn in summer, which was higher in vines treated with NitraBor™. This difference was not seen in the autumn leaf sample. Fruit B concentrations and fruit size were significantly increased by the NitraBor™ treatments compared with those in fruit harvested from the CAN treated plots. There were no differences between the treatments in fruit firmness or incidence of disorders after storage in Year 2.