Quercus pubescens and its hemiparasite Loranthus europaeus: nutrient dynamics of leaves and twigs

Abstract

Despite a long history of observations of the hemiparasitic plant, mistletoe, the mechanism of mineral movement from the host to the mistletoe is still not fully understood. In this article, we focused on the leaf development and nutrient dynamics of Loranthus europaeus and the host tree, Quercus pubescens. The nitrogen, potassium and calcium contents of leaves, current-year twigs and 1-year-old twigs were analysed. The timing of the leaf development differed between species. Leaf expansion occurred in the first 23 and 136 days, and leaf senescence took 78 and 24 days for Quercus and Loranthus, respectively. The similar nitrogen concentrations per unit leaf area may indicate that both species have the same assimilation rate. The differences in nutrient accumulation seem to support the hypothesis that nitrogen is the limiting nutrient in the transpiration stream. Larger differences in the nutrient dynamics between species were revealed in the accumulation potassium and calcium. Nutrients seemed to be transferred passively through the xylem sap between Loranthus and Quercus as we found a strong correlation between the calcium and potassium concentrations within the species and between the species. There was no correlation in the case of 1-year-old twigs, possibly due to the relatively small amount of nutrients incorporated into 1-year-old twigs and the fact that nutrient translocation occurs according the needs of the physiologically more active leaves and current-year-old twigs.