Document: DAN-3-34-14

Effect of growth at low atmospheric CO₂ on plant photosynthetic tolerance of high temperatures.

TAUB, D.R.* ^1,2, J.SEEMANN ² and J.S.COLEMAN ¹

Desert Research Institute, Reno, NV 89512 USA ¹
University of Nevada, Reno, NV 89557 USA ²

Abstract:
Our previous research has demonstrated for many plant species that growth at levels of atmospheric CO₂ greater than current ambient (360 ppm) leads to increased high temperature tolerance of photosystem II. To test whether growth at levels of CO₂ below current ambient also influences photosystem II thermotolerance, we grew plants of Cucumis sativus and Phaseolus vulgaris at CO₂ levels of 180, 280 and 360 ppm CO₂. These represent Pleistocene, recent pre-industrial and current atmospheric CO₂ levels, respectively. Intact leaves from these plants were treated at temperatures ranging from 28-46 degrees C between thermostatted brass blocks, and PSII efficiency was measured using chlorophyll fluorescence techniques. For Cucumis sativus, the efficiency of photosystem II following high temperature treatments differed for the three CO₂ treatments with 360 > 280 > 180. These differences persisted for several days following heat shock. For Phaseolus vulgaris there was a similar difference in the thermotolerance of PSII among plants grown at the different levels of CO₂, with 360 > 280 = 180.

Keywords: Elevated CO2,sub-ambient CO2, thermotolerance, PSII

This abstract is being presented at: 9:00 AM in session:
Oral Session #43: Plant Community Responses to Climate Change.