Accumulation and partitioning of dry matter and mineral nutrients in developing kiwifruit vines.

Abstract

Size, dry weight and mineral nutrient content of fruit, leaves, shoots, canes, leader, stem and roots of kiwifruit (Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson var. deliciosa) vines, aged from one to five years, were measured. The distribution of fruit yield among single canes was examined in three of the vines. Total dry weight increased from a mean of 1.29 kg vine(-1) for one-year-old vines to 29.2 kg vine(-1) for five-year-old vines. The proportion of total dry weight in roots declined from the first to the third year (55 to 40%) and then remained approximately constant, whereas the proportion of dry weight in fruits increased from the first to the third year before attaining a more or less constant value. The proportion of total canopy dry weight contained in the current season's growth (fruit, leaves and shoots) averaged 75% for all ages. Roots of five-year-old vines had only penetrated a small proportion of the total soil volume available. Total fruit yield increased linearly with number of floral shoots for whole vines and single canes within vines, but with cane size (length or dry weight) for whole vines only. The productivity of single canes declined from 2.5 kg m(-1) for canes shorter than 0.25 m to about 1.1 kg m(-1) for canes longer than 1.0 m, in accordance with a declining bud density with increasing cane length. For vines of all ages, mineral nutrient concentrations in various tissues were similar, except that Ca in leaves and S in leaves and shoots increased with vine age. Major sites of accumulation of N, Ca, Mg, S, Fe, Mn and B were the leaves, whereas P and K accumulated predominantly in the fruits, Zn in the leader, and Na and Cu in the roots. Estimated annual mineral nutrient uptake increased with vine size and fruit yield, and for five-year-old vines the values per hectare were 141 kg N, 19 kg P, 169 kg K, 161 kg Ca, 28 kg Mg, 32 kg S, and less than 2 kg for Na and all micronutrients. The nutrient content of the harvested fruit provided an inaccurate estimate of annual nutrient uptake of the developing vines.