樟子松小枝不同水分状况下蒸腾速率变化特征研究

Research on the Transpiration Characteristics at the Different Water Conditions of Pinus sylvestrisvar.mongolica

本文通过测定樟子松小枝在不同水势下的蒸腾速率变化,研究樟子松不同水分状况下蒸腾速率的变化特征,探讨了樟子松对水分胁迫的适应性。结果指出随着樟子松小枝水势下降其蒸腾速率呈下降趋势,二者关系曲线呈“S”型。初始失膨点渗透势(πp)、相对蒸腾速率(RTπp)和蒸腾速率近0拐点的水势(ψrtc)、相对蒸腾速率(RTc)可用于评价树木对水分胁迫的适应性,其值愈小,适应性愈强,其值在树木嫩枝生长期较大,而在完全木质化时期较小。

This research studied on the transpiration characteristics at different water conditions by mensurating transpiration rates under different water potentials of the branchlets of Pinus sylvetris vat. mongolica and the responses and adaptabilities to water stress. The result indicated transpiration rates decreased with the water potentials of the branchlets,and the relative curves between them were showed as “S”. The relative transpiration rates and water potentials at the initial loss point of the turgor（RTπp and πp） and at the compensation point of transpiration rate approximating to 0 （RTc and ψrtc） could evaluate the tree＇s adaptability to water stress, the values of them were small, the tree＇s adaptability was stronger. Their values were greater in the growth period of the new branchs in the annual growth of trees than in the maturation period of the branchlets.