Journal Article

Soil nitrogen limitation does not impact nighttime water loss in <i>Populus</i>

Ava R. Howard and Lisa A. Donovan

in Tree Physiology

Volume 30, issue 1, pages 23-31
Published in print January 2010 | ISSN: 0829-318X
Published online December 2009 | e-ISSN: 1758-4469 | DOI:
Soil nitrogen limitation does not impact nighttime water loss in Populus

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Nighttime transpirational water loss from C3 trees occurs without carbon gain and is both common and substantial. However, the magnitude of this water loss varies and a better understanding of the environmental factors driving this variation is needed. We investigated the response of nighttime conductance (gnight) and transpiration (Enight) to soil nitrogen limitation. We used instantaneous gas exchange measurements in greenhouse studies of Populus angustifolia James (narrowleaf cottonwood) and Populus balsamifera L. spp. trichocarpa (Torr. & A. Gray ex Hook.) Brayshaw (black cottonwood). gnight for sufficiently watered plants ranged from 0.045 to 0.308 mol m−2 s−1 for P. balsamifera and 0.037 to 0.188 mol m−2 s−1 for P. angustifolia, which was much larger than minimum leaf conductance (gmin; up to 0.005 mol m−2 s−1 in the dark). Long-term nitrogen limitation sufficient to substantially reduce biomass did not affect gnight or Enight when potentially confounding water stress effects were eliminated. We conclude that nighttime water loss from two Populus species is large and although it is under stomatal control is not regulated at night in response to soil nitrogen availability.

Keywords: drought; fertilization; nitrate; nocturnal; stomatal conductance; transpiration; water relations

Journal Article.  6048 words.  Illustrated.

Subjects: Plant Sciences and Forestry

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