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Biomass, reproductive output, and physiological responses of rapid-cycling Brassica (Brassica rapa) to ozone and modified root temperature

Published online by Cambridge University Press:  01 August 1998

CATHERINE KLEIER ,
BLAKE FARNSWORTH  and
WILLIAM WINNER
CATHERINE KLEIER
Affiliation:
Department of Biology, 4335 Life Sciences Building, UCLA, Los Angeles, CA 90095-1606, USA
BLAKE FARNSWORTH
Affiliation:
Biosphere Center, Columbia University, PO Box 689, Oracle, AZ 85623, USA
WILLIAM WINNER
Affiliation:
Department of Botany and Plant Pathology, Cordley Hall 2082, Oregon State University, Corvallis, OR 97331-2902, USA
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Abstract

Brassica rapa L. (rapid-cycling Brassica), was grown in environmentally controlled chambers to determine the interactive effects of ozone (O3) and increased root temperature (RT) on biomass, reproductive output, and photosynthesis. Plants were grown with or without an average treatment of 63 ppb O3. RT treatments were 13°C (LRT) and 18°C (HRT). Air temperatures were 25°C/15°C day/night for all RT treatments.

Ozone affected plant biomass more than did root temperature. Plants in O3 had significantly smaller total plant d. wt, shoot weight, leaf weight, leaf area and leaf number than plants grown without O3. LRT plants tended to have slightly smaller total plant d. wt, shoot weight, root weight, leaf weight, leaf area, and leaf number than HRT plants. For all variables, LRT plants grown in O3 had the smallest biomass, and plants grown in HRT without O3 had the largest biomass.

Ozone reduced both fruit weight and fruit number; LRT also reduced fruit weight but had no effect on fruit number. Ozone reduced photosynthesis but RT had no effect. Conductance and internal CO2 were unaffected by O3 or RT.

These studies indicate that plant growth with LRT might be more reduced in the presence of O3 than growth in plants with HRT, which might be able to compensate for O3-caused reductions in photosynthesis to avoid decreased biomass and reproductive output.

Keywords

OzoneBrassica rapa (rapid-cycling Brassica)root temperaturebiomassphotosynthesis
Type
Research Article
Information
The New Phytologist , Volume 139 , Issue 4 , August 1998 , pp. 657 - 664
Copyright
© Trustees of New Phytologist 1998

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