Differential Uptake, Distribution within Tissues, and Use Efficiency of Manganese, Iron, and Zinc by Olive Cultivars Kothreiki and Koroneiki

Abstract

Three-month-old rooted olive cuttings (Olea europaea L., cvs. Koroneiki and Kothreiki of ≈20 to 25 cm in height) were grown outdoors for 140 days (from 30 May until 17 Oct.) under ambient conditions in black plastic bags containing 3 kg of soil. Three soils from different parent material (Marl, Gneiss schist., and Peridotite) and with different physicochemical properties were chosen. In all the soils, ‘Kothreiki’ produced significantly greater total plant biomass compared with ‘Koroneiki’. Furthermore, between the two cultivars studied, ‘Kothreiki’ absorbed significantly greater quantity of manganese (Mn), iron (Fe), and zinc (Zn) per plant compared with ‘Koroneiki’. In all the soils, significantly greater concentrations of Mn, Fe, and Zn were recorded in the root system of both cultivars compared with those of leaves and stems. Between the two cultivars studied, ‘Kothreiki’ had greater percentage of the total Mn content distributed in the root system (74% to 80%) than ‘Koroneiki’ (44% to 56%). That high ability of ‘Kothreiki’ to accumulate Mn in its root system could possibly be advantageous in soils with high Mn concentrations and could constitute a detoxification mechanism to olive trees, protecting the above-ground part of the tree from Mn toxicity. Furthermore, greater concentrations of magnesium (Mg) were recorded in the root system of the olive plants than in leaves and stems, whereas potassium (K) and calcium (Ca) concentrations were greater in leaves compared with those of other tissues (roots and stems). The total per plant quantity of Ca, Mg, and K was significantly greater in the cultivar Kothreiki than ‘Koroneiki’ in all the soils tested. On the other hand, ‘Kothreiki’ presented significantly lower use efficiency of Mn in Marl and Gneiss schist soils, and that of Fe and Mg in all soils, so ‘Koroneiki’ could be considered as a Mn- and Fe-efficient olive cultivar, whereas ‘Kothreiki’ was Mn- and Fe-inefficient.