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Photosynthetic Characteristics in Wheat Exposed to Elevated O3 and CO2
Author(s) -
Rudorff B. F. T.,
Mulchi C. L.,
Lee E.,
Rowland R.,
Pausch R.
Publication year - 1996
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/cropsci1996.0011183x003600050029x
Subject(s) - photosynthesis , ozone , cultivar , tropospheric ozone , stomatal conductance , biology , zoology , growing season , horticulture , botany , chemistry , organic chemistry
Tropospheric trace gases such as CO 2 and O 3 have progressively increased over the past century and are predicted to increase to levels at which they may have a significant impact on agricultural production. The effects of CO 2 enrichment and O 3 air pollution on leaf photosynthesis (P n ) and stomatal conductance (g 5 ) were investigated. Two soft winter wheat ( Triticum aestivum L.) cultivars, Massey in 1991 and Saluda in 1992, were studied in field experiments at Beltsville, MD, by means of open‐top chambers to mimic atmospheric environments predicted for the first half of the 21st century. Plants were exposed to two levels of O 3 (charcoal filtered air and ambient air + an average of 40 nmol O 3 mol −1 from Monday–Friday of every week). Ozone treatments were superimposed on two CO 2 treatments (350 μmol CO 2 mol − and 500 μmol CO 2 mol −1 ). Averaged over O 3 treatments, P n was stimulated during the early and late growing season under enriched CO 2 . Averaged over CO 2 treatments, high O 3 exposure had a negative impact on P n early in the season of 1992 and a major impact late in the season of 1991 and 1992 due to premature senescence. Decreases in g s occurred under the enriched CO 2 environment and to a lesser extent with high O 3 . Interactive effects on P n and g s were mostly absent. It is likely that if CO 2 and O 3 concentrations continue to increase, the beneficial effect of CO 2 enrichment on P n may be partially negated by O 3 ‐induced stress. Conversely, damaging effects of O 3 on P n may be compensated by elevated atmospheric CO 2 .