Leaf Water Stress in Engelmann Spruce: Influence of the Root and Shoot Environments 1
AUTOR(ES)
Kaufmann, Merrill R.
RESUMO
The response of xylem pressure potential of Engelmann spruce (Picea engelmannii Engelm.) to environmental factors was studied in the natural subalpine environment. Data were analyzed in the context of a leaf water potential model based upon the van den Honert model for water transport through the soil-plant-atmosphere continuum. At soil temperatures of 10 to 15 C, xylem pressure potential decreased to about −10 bars as the ratio of leaf to air absolute humidity difference to leaf diffusion resistance (an estimate of transpiration) increased. The potentials were slightly lower at all flux rates above zero when the soil temperature was 5 to 10 C, and at temperatures of 0 to 5 C the potentials decreased sharply to as low as −20.4 bars, even though the soil water supply was adequate. The relative viscosity of water and soil to leaf resistances for flow were compared for Engelmann spruce and citrus at low soil temperatures. These comparisons indicated that decreased root permeability was probably not an important factor causing higher stresses in spruce at 5 to 10 C, but for citrus, root permeability became limiting at soil temperatures as high as 13.5 C. Xylem pressure potential was correlated with net radiation during the daytime when soil temperature was above 7 C. Under other conditions, however, xylem potential and net radiation apparently had a different relationship. The relationship between flux density and potential was the same on unshaded and shaded portions of the crown, with differences in potential related to differences in flux density.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=541936Documentos Relacionados
- Stomatal Response of Engelmann Spruce to Humidity, Light, and Water Stress 1
- Influence of Soil Water Stress on Evaporation, Root Absorption, and Internal Water Status of Cotton 1
- Water Stress Inhibits Hydraulic Conductance and Leaf Growth in Rice Seedlings but Not the Transport of Water via Mercury-Sensitive Water Channels in the Root1
- Influence of Elevated Shoot and Root Temperature on Nitrogen Fixation 1
- Response of Leaf Water Potential, Stomatal Resistance, and Leaf Rolling to Water Stress