Modelling the economic consequences of potential management changes in a mature kiwifruit orchard in New Zealand

A mathematical model simulating the growth and harvesting of kiwifruit is described. The model has been used to investigate the economic implications of changes in crop loading, winter pruning intensity, pollination method and water management. It is concluded that for mature vines, the optimum crop load is about 70 fruit m’-² (1650 fruit per vine). However, economic success may depend just as much on improvements in bud break, pollination and water management. In particular, developments in artificial methods of pollination and the use of the growth regulator, hydrogen cyanamide, are projected to potentially improve yields and profits significantly. Replacing natural by artificial shelter is also likely to be cost effective, but whether investing in irrigation is profitable depends on local circumstances. However, the results from the model must be interpreted with caution. It has been tested against a limited data set and before it can be used with confidence, further experimental work is needed to confirm its findings.