Chin J Plant Ecol ›› 2009, Vol. 33 ›› Issue (1): 150-160.DOI: 10.3773/j.issn.1005-264x.2009.01.017

• Research Articles • Previous Articles     Next Articles

EFFECTS OF DIFFERENT FLUSH SOLUTIONS ON VALUES OF HYDRAULIC CONDUCTIVITIES AND CAVITATION RESISTANCE ABILITIES OF TRESS OF POPULUS TOMENTOSA AND PINUS TABULAEFORMIS

XU Xin-Wu1,2, FAN Da-Yong1, XIE Zong-Qiang1,*(), ZHANG Shou-Ren1, ZHANG Xiang-Ying1,2   

  1. 1State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
    2Graduate University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2008-02-25 Accepted:2008-05-23 Online:2008-02-25 Published:2009-01-30
  • Contact: XIE Zong-Qiang

Abstract:

Aims Xylem hydraulic structure of water transport plays a key role in plants’ distribution, resistance to stress, etc. However, the current “flushing method” for studying characteristics of xylem hydraulic structure takes different solutions as the flushing solution, which may lead to different values of xylem hydraulic conductivity and cavitation resistance ability.
Methods We used deionized water (pH=7), the solution of 10 mmol·L-1 oxalic acid (pH=2) and 30 mmol·L-1 KCl (pH=7) as flush solutions to measure the hydraulic characteristics of tress of Populus tomentosa and Pinus tabulaeformis, which are the specific conductivities (Ks), leaf specific conductivities (Kl), xylem vulnerability curves and cavitation resistance ability (Ψ50) .
Important findings Compared with deionized water, oxalic acid and KCl as flushing solutions led to higher xylem hydraulic conductivities (Ks, Kl) in both species. With KCl flushing, the cavitation resistance abilities (-Ψ50) slightly increased in P. tomentosa and significantly increased (p<0.01) in P. tabulaeformis. However, oxalic acid led an increase in cavitation resistance in P. tomentosa but a significant decrease (p<0.01) in P. tabulaeformis. Furthermore, there was no significant linear correlation between xylem hydraulic conductivity and cavitation resistance ability for both species, measured under the same flush solution. The hydraulic conductivity with different tress length (in a range of 5-20 cm) showed that the hydraulic conductivity was stable with trees length in P. tomentosa, but greatly increased with tress length in P. tabulaeformis. Different flush solutions have different effects on xylem hydraulic structure. Furthermore, the hydraulic conductivities and cavitation resistance abilities measured with different flush solutions show a species-specific response. Thus, dynamic adjustment of components and concentration of sap in xylem conduit may facilitate a flexible response of plant hydraulic structure to changing environmental conditions.

Key words: xylem hydraulic structure, flush solution, vulnerability curve, Ionic effect