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Influence of irrigation and fertilization on transpiration and hydraulic properties of Populus deltoides

Informally Refereed

Abstract

Long-term hydraulic acclimation to resource availability was explored in 3-year-old Populus deltoides Bartr. ex Marsh. clones by examining transpiration. leaf-specific hydraulic conductance (GL), canopy stomatal conductance (Gs) and leaf to sapwood area ratio (AL:Asi)n response to irrigation (13 and 551 mm in addition to ambient precipitation) and fertilization (0 and 120 kg N ha-1 year-1). Sap flow was measured continuously over one growing season with thermal dissipation probes. Fertilization had a greater effect on growth and hydraulic properties than irrigation, and fertilization effects were independent of irrigation treatment. Transpiration on a ground area basis (E) ranged between 0.3 and 1.8 mm day-1, and increased 66% and 90% in response to irrigation and fertilization, respectively. Increases in GL, Gs at a reference vapor pressure deficit of 1 kPa, and transpiration per unit leaf areain response to increases in resource availability were associated with reductions in AL:As and consequently a minimal change in the water potential gradient from soil to leaf. Irrigation and fertilization increased leaf area index similarly, from an average 1.16 in control stands to 1.45, but sapwood area was increased from 4.0 to 6.3 m2ha-1 by irrigation and from 3.7 to 6.7 m2 ha-1 by fertilization. The balance between leaf area and sapwood area was important in understanding long-term hydraulic acclimation to resource availability and mechanisms controlling maximum productivity in Populus deltoides.

Keywords

canopy stomatal conductance, leaf area to sapwood area raito, leaf specific hydraulic conductance, water potential

Citation

Samuelson, Lisa J.; Stokes, Thomas A.; Coleman, Mark D. 2007. Influence of irrigation and fertilization on transpiration and hydraulic properties of Populus deltoides. Tree Physiology, Vol. 27: 765-774
Citations
https://www.fs.usda.gov/research/treesearch/27552