SEASONAL DYNAMICS OF BIOMASS AND MINERAL NUTRIENT PARTITIONING IN MATURE KIWIFRUIT VINES

The accumulation of dry matter plus macro- and micronutnents by various components of 6-year-old, field-grown kiwifruit vines (Actinidia deliciosa var deliciosa cv Hayward) was recorded over one season Twenty vines were harvested periodically throughout the year and separated into perennial components (roots < 20 mm diameter, structural roots, stump, stem, cordon, one-year-old fruiting wood) and current season’s growth (non-fruiting shoots, laterals on fruiting wood, leaves and fruit) There was minimal seasonal variation (CVs < 7%) in biomass change in perennial components of the vine Concentrations in these components either fluctuated about a constant value, or indicated a strong seasonal dependence Changes in biomass and nutrient concentrations in current season’s growth, however, were very regular Prior to budbreak, below-ground components contained between 48 and 81 % of the total content of each element Roots < 20 mm diameter contained more total nutrient than any other perennial component of the vine dunng the season, with the exception of Zn and Cu, which were concentrated in the cordon There was consistent accumulation of each nutrient from budbreak until harvest Rates of greatest uptake occurred in the month following budbreak, or in the 3 weeks after anthesis Between dormancy and harvest, whole-vine contents increased for all nutrients Increases m Fe, Mg, P, S and Zn ranged from 21 % (Zn) to 88% (Mg), and m B, Ca, Cl, Cu, K, N and Mn from 109% (Cu) to 302% (Cl) Despite the large requirements of the current season’s growth, net changes in the seasonal content of perennial components were relatively small Copper, Mg, P, N and Cl were the elements in which perennial reserves were utilized to the greatest extent to meet transient deficits between nutrient demand for the current season’s growth, and that recently taken up from soil Generally, reserves utilized dunng the penod of vegetative growth were replaced by harvest-time These observations, based on application of a single fertiliser dressing before budbreak, suggest the vine maintains satisfactory fertility without the need for late-season or post-harvest applications of fertiliser to supplement nutnent reserves, as occurs with some other fruiting crops. © 1992 Annals of Botany Company.