Seasonal uptake and distribution of nutrient elements by kiwifruit vines 1. Macronutrients

Abstract

Dry matter production and uptake and distribution of macronutrients in kiwifruit vines (Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson var. deliciosa) cv. Hayward were studied in sand culture. The total dry mass of the kiwifruit vine increased sharply from bud break (Oct. 10) until the beginning of March. The largest increases took place in above-ground new growth (47%), while root mass increased by 33%. The contribution of roots to the total dry mass decreased from 60% during dormancy to 40% at harvest. From dormancy to three weeks after flowering there was a tendency for dry mass of roots, wood and bark to decrease, which might have been due to utilization of carbohydrate reserves by the developing vine. This decrease in dry mass was less pronounced than had been reported for other deciduous fruit trees and grape-vines. There were indications that especially nitrogen, and to a lesser extent potassium reserves from roots and bark could play an important part in the development of the vine shortly after bud break. During a 4–7-week period prior to harvest, potassium was translocated from leaves, bark and wood to fruit. Since the fruit is such a strong sink for potassium, application of sufficient potassium fertilizer in spring is essential to ensure optimal growth as well as production. The kiwifruit vine has a high calcium requirement and 50% of the calcium taken up during the season was translocated to leaves. The root system constitutes an important organ for reserve nutrients. Although roots made up only 60% of the total mass of the vine during dormancy, they contained 75–85% of the total macronutrient content of the vine at that stage.