油蒿不同部位水分关系研究

应用植物PV技术研究油蒿（Artemisia ordosica Krasch）不同部位（营养枝、生殖枝、1年生枝、2年生枝、3年生枝、根系）的持水性能及其在SPAC系统的水分运移中的作用。结果表明：油蒿不同部位具有相似的水分生理特点,但各参数差异比较明显。随着木质化程度的增加,枝条（除生殖枝）饱和时最大渗透势（Ψ100π）、初始质壁分离时的渗透势（Ψ0）、相对水分亏缺（D0RW）、相对渗透水分亏缺（D0ROW）、束缚水含量（Vb）、细胞组织最大弹性模量（εmax）及ΔΨ（Ψ100π－Ψ0）逐渐增大,而自由水含量（Vf）则逐渐减小。生殖枝的Ψ100π、Ψ0、D0RW、D0ROW则大于其他枝条,根系的Ψ100π、Ψ0、D0RW、D0ROW、Vb、εmax均大于枝条,而Vf和ΔΨ小于枝条。随木质化程度增加,枝条的总水容（C）逐渐减小。C表现出两段性,在膨压消失前,枝条的水容（C1）变化不大,而在膨压消失后枝条水容（C2）随木质化程度增加而减小;总体来看,生殖枝的水容大于其他枝条,而根系水容最大。在水分胁迫条件下,木质化程度低的枝条,其较小的束缚水含量（Vb）及弹性模量（εmax）和较大的水容（C）不利于其保持体内水分以及较高的水势和膨压;而木质化程度高的枝条,其较高的束缚水含量及坚硬厚实的细胞壁则有利于其保持体内水分;根系较大的Vf和C,表明其容易失水的特性,有利于SPAC系统水分传输。

Water Relations of Different Parts of Artemisia ordosica

Water parameters of different parts (reproductive shoot, vegetative shoot, annual tress, biennial tress, trunk, roots) of Artemisia ordosica and their roles in water transfer of SPAC system were studied by using the plant pressure-volume technique. The results showed that different parts of Artemisia ordosica had the similar water physiology, but significant differences existed among these parameters. With the increase of lignification, the maximum osmotic potential at saturated point(Ψ100π), osmotic potential (Ψ0), relative water deficit (D0RW), relative osmotic water deficit at turgor loss point(D0ROW), bound water content(Vb) and bulk elastic modulus(εmax) of the tress (except for reproductive shoots) all increased, while free water content(Vf) decreased. The Ψ100π, Ψ0, D0RWand D0ROW of the reproductive shoot were higher than that of the other kinds of tress; the Ψ100π, Ψ0, D0RW, D0ROW, Vb and εmax of the root were higher than that of any kind of tress, while Vf and (ΔΨ of the root were lower than that of tress. In addition, the total hydraulic capacitance(C) of tress generally decreased with the increase of lignification, but for details, there were no obvious differences among different kinds of tress before turgor loss and gradually decreased after turgor loss. As a whole, the C of reproductive shoot was higher than that of other tress, and the C of root was the highest one. Under the condition of drought, new tress tended to lose its water and to keep low water potential and turgor because of its low bound water content, low bulk modulous and high hydraulic capacitance; while old tress could hold their water because of their high bound water content, stiffer and thicker cell wall. The root was characterized by high free water content and hydraulic capacitance, which showed a property of being prone to lose water easily and was beneficial to the water transfer in SPAC system.