Seasonal changes of mineral nutrients in olive leaves during the alternate-bearing cycle

Abstract

Samples of olive ( Olea europaea L.) leaves developed in 1993, 1994 or 1995 were collected separately from non-irrigated, mature trees at monthly intervals during 1994 (`off' year) and 1995 (`on' year) to determine leaf-nutrient concentration and nutrient content per leaf. N, P, K and Mg contents were affected by crop load, showing lower values following the `on' year. No effect of crop load was observed on micronutrient accumulation in leaves, probably because of the lower requirements for these elements of the olive fruit. Leaf age also influenced leaf-nutrient concentration and nutrient content. Leaf N, P, K, Zn and B concentrations were higher in younger leaves, whereas leaf Ca, Mg, Mn, Cu and Fe concentrations were higher in older leaves. Ca, Mg, Mn, Cu and Fe content per leaf were also higher in older leaves. There was little or no difference in P, K, Zn and B content among leaves of different ages. N content per leaf was higher in older leaves during the growing period of the `off' year. Seasonal mineral fluctuations curves for different leaf mineral nutrients were developed which could be used in the interpretation of leaf analysis.