Document: PAU-3-30-6

Acclimation in respiration in white oak (Quercus Alba).

BOLSTAD, P.V.* and P.B.REICH

University of Minnesota, Minneapolis, MN ¹

Abstract:
We report on two experiments that reveal acclimation in leaf respiration for Quercus alba (L.). In the first experiment seedlings from three geographic sources along a large climate gradient were grown in each of four controlled-environment chambers. Temperatures were set to a high temperature (26-34 ^oC) and a low temperature regime (16-24 ^oC) in each of two chambers. Light and temperature varied in a four-step diurnal pattern. Respiration was measured at a fixed temperature (24 ^oC) every third day for approximately two weeks, and respiration was measured at 12, 18, 24, and 30 ^oC at the end of the two-week interval. Chambers were then switched to the opposite temperature regime, cool to warm, and warm to cool, for the subsequent two-week period. In the second experiment we grew seedlings from three geographic sources in each of three replicate controlled environment chambers. All settings were identical in the chambers except for temperature. Chambers were set to a warm treatment (24-26 ^oC) or a cool treatment (14-16 ^oC). Leaf respiration was measured every two days at a fixed temperature (24 ^oC) for three leaves from each source in each chamber. Temperature regimes were switched after four days in each chamber (cool to warm, and warm to cool). Chambers were cycled from cool to warm treatments every six days for a 30 day period. Respiration at the fixed temperature (24 ^oC) was higher for plants in a cool treatment when compared to plants in a warm treatment. Leaf respiration also exhibited very rapid acclimation to growth temperature. Respiration rates measured in the first experiment increased significantly during the two-week cool treatment. These rates reverted to lower levels when the plants were returned to the warm treatment for two weeks. Most of the acclimation was rapid, as within two days, plants appeared to have completed most of the shift in respiration to the new temperature regime. Respiration acclimation appears to be reversible, in that observed respiration rates at a fixed temperature decreased and increased through many warm and cool treatment cycles.

Keywords: plant respiration, acclimation

This abstract is being presented at: 2:30 PM in session:
Oral Session #50: Plant Gas Exchange.