Different effects of hemi-parasite Taxillus chinensis on water transport of its host angiosperms and gymnosperms trees

Abstract

Taxillus chinensis (DC.) Danser (Loranthaceae) is a hemi-parasite widely distributed in south China. It can parasitize not only on angiosperms but also on gymnosperms, which has different influences on water transportation of the two types of host trees. The safety of plant water transportation is a key factor affecting plant growth. This study measured the sap flow of angiosperms (Liquidambar formosana, Michelia chapensis) and gymnosperms (Taxodium ascendens, Taxodium distichum) parasitized by T. chinensis, combined with leaf water potential, leaf photosynthesis and transpiration to analyze the water transport differences between these two types of host plants. We obtained the following important findings: The whole tree transpiration of gymnosperm hosts was lower than that of non-hosts. The water use efficiency and midday leaf water potential of T. chinensis were significantly lower than those of all hosts. Leaf stomatal conductance, photosynthetic rate and leaf transpiration rate of T. chinensis which parasitized on gymnosperms were higher than that of T. chinensis parasitized on the angiosperms. We found that T. chinensis had a negative impact on the stomatal conductance and the water transpiration of gymnosperm hosts. This is the first study exploring the water uptake of T. chinensis from different hosts at the leaf and whole tree scales, and deepens the understanding of the physiological characteristics and the adaptive mechanisms of hemi-parasites on different hosts.