Nutrient uptake pattern of satsuma mandarin (Citrus unshiu Marc.)

The study aimed at determining the uptake (accumulation) of plant nutrients in Satsuma mandarins. To achieve this objective, samples were taken and analyzed at monthly intervals for two years from active organs (one-year-old and seasonal branches and the buds, flowers, fruit and leaves) on selected trees in 15 orchards representative of the extensive Satsuma producing region in Izmir. In evaluation of the trends, seasonal biomass increases and plant nutrient contents of the sampled organs (buds, flowers, leaf, branch etc.). After harvest, trees were pruned at ¼ severity-rate, and number of branches formed during the season counted and seasonal biomass accumulation calculated. In calculations, nutrients removed through harvested fruit yield and by pruning were also considered. The results displayed that initial biomass at the beginning of the vegetation period (end of March), which was calculated as 10 kg/tree increased and totaled to 58 kg/tree after harvest (mid-December) including branches formed during the season. Biomass formation rate fluctuated based upon the growth of the branches and fruit, and 89 % of the biomass formed until August. The increase rate slowed down thereafter. Twenty four % of the total biomass comprised of fruit, 53% of leaves and 23 % of wood. The contribution of one-year-old branches was relatively less (19%) due to the continuous leaf and wood growth. Leaf N and Ca concentrations decreased throughout the growth period; Ca and Mg levels increased, whereas P, K, Fe, Zn and Mn concentrations first decreased and then increased. During one vegetation period (end of March to mid-December), the accumulation of plant nutrients totaled to 1214 g N, 122 g P and 1142 g K/tree. The results for Ca and Mg were 1617 and 236 g/tree; and for Fe, Cu, Mn and Zn 6 g, 0,6 g, 2 g and 1 g/tree, respectively. Obtained data revealed that the major part of the accumulated plant nutrients were supplied through remobilization. Seasonal accumulation of plant nutrients can be summarized as follows: N: 19% accumulated until the first month of the vegetation (growth) period, 66% by the third month and 96% by the 5th month; these rates were 11; 34; and 66% for P, and 16; 45; and 77%, respectively for K. In Satsuma mandarins, the total amount of nutrients removed through harvested fruit (40-160 kg/tree) and pruning (8-12 kg/tree) were calculated as 1302 g N; 128 g P and 1222 g K/tree.