当前位置： SCI文献检索 > OECOLOGIA期刊下所有文献 > Variation in hydraulic architecture and gas-exchange in two desert sub-shrubs, Hymenoclea salsola (T. & G.) and Ambrosia dumosa (Payne).

Variation in hydraulic architecture and gas-exchange in two desert sub-shrubs, Hymenoclea salsola (T. & G.) and Ambrosia dumosa (Payne).

Abstract：

:Adjustment of hydraulic architecture in response to environmental conditions was studied in two warm-desert sub-shrubs, Hymenoclea salsola and Ambrosia dumosa, both at the level of genetic adaptation along a climatic gradient and plastic response to immediate growth conditions. Individuals of both species originating from southern populations developed higher leaf-specific hydraulic conductance in the common greenhouse than individuals from northern populations. Hydraulic conductance was higher in plants grown at high temperature, but did not vary as a function of growth relative humidity. Hydraulic conductance was not correlated within species with individual variation in vessel diameter, cavitation vulnerability, or root:shoot ratio, but was strongly, negatively correlated with the fraction of total plant biomass allocated to leaves. For both species, stomatal conductance (g s) at high leaf-to-air vapor pressure difference (ν) was tightly correlated with variability in hydraulic conductance, as was the sensitivity of stomatal closure to increasing ν. Experimentally increasing shoot water potential by soil pressurization, under conditions where high ν had already caused stomatal closure, led to substantial stomatal reopening in both species, but recovery was significantly higher in H. salsola. Hydraulic conductance was higher in H. salsola than A. dumosa. H.salsola also differed from A. dumosa by being a representative of a highly specialised group of desert shrubs which use the twigs as a major photosynthetic organ. The southern population of H. salsola produced far fewer leaves and relied much more heavily on twig photosynthesis than the northern population. At the whole-plant level, increased reliance on twig photosynthesis was associated with higher leaf-specific hydraulic conductance, but equivalent whole-plant photosynthesis on either a dry weight (µmol CO2 g-1) or nitrogen basis (µmol CO2 g-1)). This suggests that twig photosynthesis might be one way of increasing hydraulic conductance per unit photosynthetic canopy by increasing allocation to an organ which simultaneously performs photosynthetic, support, and transport functions.

journal_name

Oecologia

journal_title

Oecologia

authors

Comstock JP

doi

10.1007/PL00008879

subject

Has Abstract

pub_date

2000-10-01 00:00:00

pages

1-10

issue

eissn

0029-8549

issn

1432-1939

pii

10.1007/PL00008879

journal_volume

125

pub_type

杂志文章

在线工具

Variation in hydraulic architecture and gas-exchange in two desert sub-shrubs, Hymenoclea salsola (T. & G.) and Ambrosia dumosa (Payne).