Studies On Characteristic Of Water Consumption And Anatomical Structure In Woody Plants

In this paper, some studies on the water consumption of the main plantation tree species in Northern China such as Cotinus coggygria Scop, Platycladus orientalis L. > Rhus typhina L. and Pinus tabulaeformis Carr, were carried out under water stress condtion in green house by the mean of manual simulative drought using BP3400 nicely ectronical balance in different time. The anatomy structure of trees' roots ^ stems and leaves which controlling transpiration were studied at the same time by optical microscopy and scan electron microscopy. It aims at selecting tree species with stronger drought tolerance, increasing the survival rate in afforestation and conservation rate in arid and semi-arid region.The speed on water consumption of broadleaf (Cotinus coggygria Scop^ Rhus typhina L.) was 5-7 times of conifer (Platycladus orientalis^ Pinus tabulaeformis) under the normal water condition; under the drough stress, the speed of water consumption was Rhus typhina L. > Cotinus coggygria Scop> Platycladus orientalis> Pinus tabulaeformis The daily change in the rate of water consumption of every tree was obvious "single apex type" under enough water condution, and the daily largest quantity and speed of water consumption were at 10:00-14:00am; when the seedings were subjected to moderate drought stress, their most speeds would bring forward; in drought stress, the range of daily change in rate of water consumption becomed slowly, which the "single apex type" was not evident, and there was "double apex type". Whether the drought stress or not, the quantity of water consumption at 10:00~14:00am was about half of which in the whole day.The lognitudinal resistance of water flowing in the root in broadleaf tree (arbor > shrub and liana) was more less than which in conifer tree. The results showed that the ability of controlling water flow in conifer tree species was stronger than broadleaf tree species. The pit diameter of conifer tree speceis (Pinus tabulaeformis Carr.) was obviously bigger than broadleaf tree speceis (Acer truncatum), the density and area ratio of pit were less than broadleaf tree. Compared with the constriction areas, the diameter of pit in the no- constriction areas was smaller, but the density and area ratio of pit were higher.The mesic structure of leaf in these broadleaf tree speceis was obvious. The leaf anatomy structure was lightly drought nature: palisade tissue,vascular tissue and crystal cell. Especially the vascular tissue structure with double hypoderm and phloem in Cotinus coggygria could transport water effectively in order to ensure plant's security under water stress. From the leaf anatomic stucture, the ability of controlling water transpiration in conifer trees species withdeveloping cutin layer and deep stomia was stronger than in broadleaf.