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Influence of Ozone Stress on Soybean Response to Carbon Dioxide Enrichment: II. Biomass and Development
Author(s) -
Miller J. E.,
Heagle A. S.,
Pursley W. A.
Publication year - 1998
Publication title -
crop science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.76
H-Index - 147
eISSN - 1435-0653
pISSN - 0011-183X
DOI - 10.2135/cropsci1998.0011183x003800010021x
Subject(s) - ozone , carbon dioxide , biomass (ecology) , point of delivery , dry weight , zoology , horticulture , charcoal , biology , growing season , botany , chemistry , agronomy , ecology , organic chemistry
Previous research has shown that elevated CO 2 concentrations can increase plant growth, whereas the air pollutant O 3 is phytotoxic. Because elevated concentrations of these gases will co‐occur, the objective of our experiment was to determine if estimates of plant growth response to future levels of CO 2 and O 3 require experiments to test the gases in combination. Soybean plants [ Glycine max (L.) Merr. cv. Essex) were exposed in open‐top chambers to combinations of O 3 and CO 2 from plant emergence through physiological maturity. Ozone treatments were charcoal‐filtered air (CF), nonfiltered air (NF), and NF with O 3 added for 12 d −1 (NF+) (seasonal mean 12 d −1 O 3 concentrations of 20, 50, or 79 nL L −1 , respectively). Carbon dioxide exposures were for 24 h d −1 giving seasonal mean 12 d −1 concentrations of 370, 482, 599, or 713 μL L −1 . Over the season, elevated CO 2 usually stimulated growth and O 3 suppressed growth. Elevated CO 2 usually increased partitioning of biomass to branches, decreased partitioning to pods, increased specific leaf weight, and decreased leaf area ratio. Ozone suppressed leaf and root weight ratios, increased pod weight ratios, and decreased specific leaf weight. Toward the end of the season, both O 3 and CO 2 accelerated reproductive development. Elevated CO 2 moderated suppression of growth by O 3 , and the highest CO 2 concentration completely ameliorated O 3 effects on main stem biomass, root biomass, and leaf area. Ozone, however, limited some positive growth responses to CO 2 , especially at less than a doubling of CO 2 concentrations. These results indicate that in order to understand the future impacts of atmospheric gases such as elevated CO 2 and O 3 on crop growth, their combined effects should be determined.