Hierarchy of plasticity traits in responses of Quercus aliena to light conditions and water availability

This study aimed to investigate plasticity of different plant traits to varied light and water availability. A greenhouse experiment was conducted with Quercus aliena seedlings with two light and four soil water levels. Plant traits related to leaf physiology, morphology, anatomy, and biomass production were determined. The results showed that plant size had significant effects on leaf area, leaf number, shoot height, basal diameter and crown area. After excluding the influence of plant size, water treatment had stronger effects on plants compared to light levels, and their interaction effect was significant. The limited water supply significantly inhibited leaf photosynthetic rate and the fluorescence efficiency under high light. However, leaves submitted to moderate drought stress showed enhanced fluorescence activity under shade condition. Grand plasticity of leaf physiology and growth was the highest, followed by biomass allocation and leaf morphology, and lastly anatomy, and this ranking did not change as resources considered. Among the variables, leaf petiole length, chlorophyll content and leaf area could be selected as candidates for estimation of species’ plasticity to water, light and their interaction, respectively. Therefore, our results suggested that there was a hierarchy existing among traits plasticity in Q. aliena, and supported the aboveground facilitation hypothesis that shade could alleviate the adverse effect of drought.