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The interactive effects of CO{sub 2} and drought on physiological responses of quaking aspen seedlings

Journal Article · · Bulletin of the Ecological Society of America
OSTI ID:95846
;  [1]
  1. Univ. of Wisconsin, Madison, WI (United States)
To examine the effects of CO{sub 2} and drought on gas exchange, biomass partitioning, and carbon allocation in quaking aspen, we utilized 24 planters, each with 9 2-yr old quaking aspen and 11 3-yr old sugar maple seedlings interplanted. Each planter had 200 l of soil volume, chamber photon levels of 700 {mu}mol m{sup -1} s{sup -1}, and replicated ambient (37 Pa) and elevated (70 Pa) CO{sub 2} treatments. We withheld water from drought planters for 27-30 days, and {sup 14}C labelled 1 leaf per aspen seedling per planter, with 48-hour chase periods before harvest. Photosynthetic rates were 11.0{+-}0.4, 8.3{+-}0.2, 2.9{+-}0.5, and 2.4{+-}0.5 {mu}mol m{sup -1} s{sup -1} for elevated/control, ambient/control, elevated/drought, and ambient/drought treatments respectively. The ratio of instantaneous photosynthesis/transpiration for drought plants was twice the ambient control values and 8 times the elevated control values. Pre-dawn leaf water potentials at harvest were -1.6{+-}0.1 and -0.3 MPa for the combined drought and control treatments, respectively. The most pronounced interaction was significantly higher root/shoot biomass ratios and increased carbon allocation to roots in the elevated/drought treatment. The lack of root restriction may have maintained root sink strength, and enhanced leaf photosynthesis in the elevated/control treatment.
OSTI ID:
95846
Report Number(s):
CONF-9507129--
Journal Information:
Bulletin of the Ecological Society of America, Journal Name: Bulletin of the Ecological Society of America Journal Issue: 2 Vol. 76; ISSN BECLAG; ISSN 0012-9623
Country of Publication:
United States
Language:
English

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