Differences in leaf functional traits and allelopathic effects on seed germination and growth of Lactuca sativa between red and green leaves of Rhus typhina

Abstract

The leaves of the invader Rhus typhina are heterochromatic in different periods during its life cycle. This study aims to address the differences in leaf functional traits and allelopathic effects on seed germination and growth of Lactuca sativa between green and red leaves of R. typhina. The leaf chlorophyll and N concentrations, single-leaf wet and dry weights, and leaf thickness of green leaves of R. typhina were significantly higher than those of red leaves of R. typhina but specific leaf area and leaf moisture content demonstrated the opposite. Thus, the resource investment per unit area and per lamina of red leaves of R. typhina is significantly lower than that of green leaves of R. typhina due to the low leaf chlorophyll concentration for red leaves. Seed germination and growth of L. sativa inhibited significantly with increasing extract concentrations both of R. typhina green and red leaves. Thus, more allelochemicals may be released into the invaded ecosystems under the invasion of R. typhina with increasing invasion degree and time presumably and then trigger more noticeably allelopathic effects on the performance of associated plant species. Allelopathic effects on seed germination and growth of L. sativa of R. typhina red leaves are obviously higher than that of R. typhina green leaves. The main reason may be that the type of R. typhina red leaves is aged and the free nutrient compositions have been transported to other position but the main secondary metabolites retained in the aged leaves. The forest management for R. typhina might be better progressive in advance before the brilliant red foliage of R. typhina occurs before mid-autumn generally to obtain effective invasion prevention and control.