Effect of sampling time and soil type on Mn, Fe, Zn, Ca, Mg, K and P concentrations of olive (Olea europaea L., cv. 'Koroneiki') leaves

It has been studied the time course of seven leaf nutrients' (Mn, Fe, Zn, Ca, Mg, K and P) concentrations when plants of the olive cultivar 'Koroneiki' were grown for about 5 months (from the 30th of May till the 17th of October) in three soils from different parent materials (Marl, Gneiss schist and Peridotite), located in the region of Central Macedonia, Northern Greece. The data indicate that leaf Mn concentration of olive plants, independently of soil type, was gradually increasing reaching a maximum from August to early September and afterwards declined until the end of the experiment. Another conclusion comparing the three soils was that significantly lower concentrations of Mn were recorded from early July and afterwards in the plants grown in the Gneiss schist soil, compared to the Marl and Peridotite ones. Leaf magnesium concentration was fluctuating during the 5-month experimental period: furthermore, significantly greater Mg concentrations were recorded from the middle of August until the termination of the experiment in olive plants grown in the Peridotite soil, compared to the other two ones. Phosphorus concentration was gradually increasing and reached its maximum value during the middle of summer. In addition, among the three soils, significantly greater concentrations of P were recorded in the Peridotite soil, from the beginning until the middle of September, compared to the other two soils. It should be pointed out that with few exceptions (a few Mn concentrations being <20 mg/kg d.w., some Fe concentrations being <50 mg/kg d.w., most of Mg concentrations in the Gneiss schist soil and a few ones in the Marl soil being <0.1% d.w., which could be characterized as relatively, but not seriously, deficient), all the other nutrient concentrations were sufficient, or in abundance (as for example happened with P). Finally, the fluctuation with time of the concentrations of all the other nutrients (Fe, Zn, Ca and K) was similar among the three soils and was not affected by the soil type. (C) 2010 Elsevier B.V. All rights reserved.