Dynamic of nutrient uptake and partitioning within yellow-fleshed kiwifruit (Actinidia chinensis var. chinensis) organs

The aim of the study was to establish the dynamic of mineral nutrient uptake and partitioning within the new growth of yellow flesh kiwifruit. The trial was carried out near Brisighella, Italy (44 degrees 13'20"N, 11 degrees 46'24"E), in an orchard planted in 2014 in a loamy, nutrient-balanced soil. Shoot length and number of leaves were determined every two weeks from May 16 to September 19. Fruit growth was detected from May 16 until harvest (October 1). At the end of the season, biomass of abscised leaves and wood from the winter pruning was determined. Leaves and fruits collected during the season, thinned fruits, pruned shoots and wood and abscised leaves were weighted and analysed for macro- and micronutrients. At the end of July, macronutrients found in the leaves reached the levels of 64, 5, 54, 99 and 16 kg ha-1 for N, P, K, Ca and Mg, respectively. At harvest, in the fruits, we found 77, 10, 74, 11 and 5 kg ha(-1) of N, P, K, Ca and Mg, respectively; B, Cu and Fe were the most abundant micronutrients in the fruits (100, 84 and 108 g ha(-1), respectively). Macronutrient uptake and partitioning to leaves and fruits increased linearly until harvest. Fruit Ca partitioning ceased in August, while leaf Ca accumulation continued until leaf senescence. Fruit N and K accumulation continued until harvest. Summer and winter pruning wood accumulated 32, 3, 17, 23 and 6 kg ha(-1) of N, P, K, Ca and Mg, respectively, mainly in 1-year-old shoots. Considering the whole plant new growth (thinned fruits, pruned wood, harvested fruits and abscised leaves), the amount of N, P, K, Ca and Mg taken up during the season was 143, 16, 105, 202 and 38 kg ha(-1).