Lightle , Nicole Elizabeth , Heckathorn, Scott .
Indirect effects of heat stress on roots of white oak (Quercus Alba).
Anthropogenically-driven climate change will increase the frequency, severity, and duration of acute heat-stress events (heat waves) for terrestrial plants, and this is expected to have a strong negative impact on many forested ecosystems. Currently, knowledge of heat-wave effects on trees is lacking. Available evidence indicates that heat waves affect both shoots and roots, and that effects on roots are often indirect (e.g., from heat-induced water stress). We investigated indirect root effects of an abrupt heat-wave on white oak (Quercus alba) seedlings, by increasing daytime temperatures from 28 to 35oC in plants wherein both shoots and roots were heated vs. those in which only shoots were heated (and roots were insulated). Insulation of roots prevented increases in soil temperature during heating (control/insulated = 25oC maximum daytime temperature, un-insulated = 30-31oC). Heating lowered net photosynthesis (but not stomatal conductance) and leaf water potential, and the decreases were greater for plants with insulated roots. When measured at 35oC, root respiration (R) was greater in roots from insulated than un-insulated plants, and root R in heated plants was ca. two-fold higher than in control plants; at 22oC, root R did not differ among treatments. These results (1) confirm that there are indirect effects of heat-waves on root function, and these indirect effects include effects on both water and C relations; and (2) have implications for conducting climate-change experiments and in understanding response to heat waves in field-grown plants.
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1 - University of Toledo, Evnvironmental Science, 2801 W Bancroft St, MS 604, Toledo, OH, 43620, USA
2 - University Of Toledo, EARTH, ECOLOGICAL & ENVIRONMENTAL SCIENCES, MS 604, 2801 W. Bancroft, TOLEDO, OH, 43606-3390, USA
acute heat stress
Presentation Type: Oral Paper:Papers for Topics
Date: Tuesday, July 10th, 2012
Time: 8:15 AM