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

1 INTRODUCTIONAs an important structure in the leaves of terrestrialplants, stomata play a key role in the gas exchangebetween plants and atmosphere, and provide the mainchannels of water dissipation for plants. They also playa significant part in the regulation of photosynthesisand evaporation process. Researches have long beenconducted on stomata, and one of the most importantfields in plant physiological and ecological research isconcerned with the physiological and ecologicalcharacteri…

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

Stomatal characteristics and its plasticity were surveyed in leaves of four canopy species, Shoreachinensis, Pometia tomentosa, Anthocephalus chinensis, Calophyllun polyanthum and three middle-layerspecies, Barringtonia pendula, Garcinia hanburyi, Horsfieldia tetratepala, acclimated to different lightconditions for more than one year. All plants stomata are distributed on the abaxial of leaves. Pometiatomentosa and Barringtonia pendula have higher stomatal density and the guard cell length of Anthocephaluschinensis 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, whilenumbers of stomata per leaf were higher in the low than the high relative PFD, and stomatal conductance ofleaves was the highest in the 50% of full light except for Anthocephalus chinensis. The relative PFD has littleeffects on the guard cell length of all seven plants. We have also found a significant negative correlationbetween stomatal density and leaf area, but the stomatal conductance was not significantly positive with thestomatal conductance. The analysis of phenotypic plasticity of stomatal characteristics showed: plasticityindex 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 canopyspecies than middle-layer species. The high plasticity of canopy species was consistent with the hypothesisthat specialization in a more favorable environment increases plasticity.