Response of Somatal Characteristics and its Plasticity to Different Light Intensities in Leaves of Seven Tropical Woody Seedlings

摘要

Stomatal characteristics and its plasticity were surveyed in leaves of four canopy species, Shorea chinensis, Pometia tomentosa, Anthocephalus chinensis, Calophyllun polyanthum and three middle-layer species, Barringtonia pendula, Garcinia hanburyi, Horsfieldia tetratepala, acclimated to different light conditions for more than one year. All plant's stomata are distributed on the abaxial of leaves. Pometia tomentosa and Barringtonia pendula have higher stomatal density and the guard cell length of Anthocephalus chinensis and Calophyllun polyanthum were much greater than others'. Stomatal density and stomatal index (ratio of stomatal numbers to epidermal cell number) were increased with growth irradiance increased, while numbers of stomata per leaf were higher in the low than the high relative PFD, and stomatal conductance of leaves was the highest in the 50% of full light except for Anthocephalus chinensis. The relative PFD has little effects on the guard cell length of all seven plants. We have also found a significant negative correlation between stomatal density and leaf area, but the stomatal conductance was not significantly positive with the stomatal conductance. The analysis of phenotypic plasticity of stomatal characteristics showed: plasticity index for stomatal index and numbers of stomatal per leaf were similar for canopy and middle-layer species,while the plasticity index of stomatal density and stomatal conductance were significantly greater for canopy species than middle-layer species. The high plasticity of canopy species was consistent with the hypothesis that specialization in a more favorable environment increases plasticity.