The Comparative Study of Leaf Water Characteristics and Characteristics of Stem Hydraulic Conductivity in Eight Species

In this paper, the Beijing Botanical Garden introduction and cultivation of plant Metasequoia ( Metasequoia glyptostroboides H. ) , ginkgo ( Ginkgo biloba L. ) , cedar ( Cedrus deodara G. ) , Chinese white poplar (Populus tomentosa C.), home elm (Ulmus pumila L.) , the Ulmus macrocarpa (Ulums macrocarpa H.), weeping willow (Salix babylonica L.) and wisteria (Wisteria sinensis S.) study by the PV curve , hydraulic conductivity and anatomy eight kinds of plant leaf water parameters , stomatal characteristics and the characteristics of stem hydraulic conductivity and xylem anatomical structures were analyzed . The results show that : 1 leaf water parameters obtained from the PV curve different months of the same species, moisture characteristics have obvious differences . The variation of the different types of plant species is inconsistent , with trees of adaptability to the environmental conditions ( light , moisture , temperature , etc.) and the hysteresis . The ψs and ψw gymnosperms in the fast-growing period ( July -September) the higher saturated osmotic potential (ψs) , and the loss of turgor point water potential (ψw) value ; xerophytic trees Populus tomentosa lower performance in the fast-growing value. Other species variation is not obvious . Mean leaf water parameters as well as various species stomata Comparative Study of the eight species divided into four different ecological types : (1) higher ψs ψw, lower stomatal density and smaller pores gymnosperms the the Metasequoia , ginkgo and cedar ; ( 2 ) lower ψs ψw, large cell elastic modulus , lower stomatal density and smaller pores xerophytic trees Populus tomentosa ; ( 3) higher ψs ψw, higher stomatal density and larger pores house elm, Ulmus macrocarpa and weeping willow ; (4) lower ψs and ψw, higher stomatal density and smaller stomata wisteria vine . 3.8 species stems guide water features significant differences gymnosperm tracheid density , but the worst water conductivity , and the vine wisteria vessel diameter showed strongest hydraulic conductivity characteristics . Xeric , xeric trees located between the two . . Species Huber value was negatively correlated with the other three hydraulic structure parameters , correspondence and coherence with its own structure and function of plants in water transport and diffusion . Catheter or tracheid diameter with maximum hydraulic conductivity , conductivity and leaf specific conductivity of positive , indicating that the larger diameter catheter is more conducive to the transmission of moisture .