Development of a leaf sampling technique and leaf standards for kiwifruit in New South Wales

Abstract

The nutrient composition of foliage from mature vines of the kiwifruit varieties, Hayward and Bruno was monitored monthly over 3 consecutive growing seasons in an orchard on the central coast of New South Wales. Within a season, concentrations of N (5.07-2.74%), P (1.0-0.44%), K (3.29-1.95%) and Zn (36-19 mg/kg) in the first leaf after the fruit generally declined while concentrations of Ca (1.4 1 - 4.21%), Mg(0.28-0.50%) and Mn (151-275 mg/kg) increased. Leaf composition was relatively stable in February and this is proposed as a suitable standard sampling time for leaf analysis in New South Wales. Only minor differences in nutrient composition were found between the first leaf and other potential index leaves remaining on shoots at this time. Using this leaf sampling procedure, commercial kiwifruit orchards in New South Wales were surveyed over 3 consecutive seasons. The applicability of the New Zealand leaf analysis standards for use in New South Wales was assessed by comparing the predicted and actual performance of orchards in the survey. Where unreasonable divergence between the two was noted the standards were amended to make them more relevant to field conditions in New South Wales.