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Title: Influence of elevated carbon dioxide on water relations of soybeans

Journal Article · · Plant Physiol.; (United States)
DOI:https://doi.org/10.1104/pp.74.2.233· OSTI ID:6598144

Soybean (Clycine max L. Merrill cv 'Bragg') plants were grown in pots at six elevated atmospheric CO/sub 2/ concentrations and two watering regimes in open top field chambers to characterize leaf xylem potential, stomatal resistance and conductance, transpiration, and carbohydrate contents of the leaves in response to CO/sub 2/ enrichment and water stress conditions. Groups of plants at each CO/sub 2/ concentration were subjected to water stress by withholding irrigation for 4 days during the pod-filling stage. Under well watered conditions, the stomatal conductance of the plants decreased with increasing CO/sub 2/ concentration. Therefore, although leaf area per plant was greater in the high CO/sub 2/ treatments, the rate of water loss per plant decreased with CO/sub 2/ enrichment. After 4 days without irrigation, plants in lower CO/sub 2/ treatments showed greater leaf tissue damage, lower leaf water potential, and higher stomatal resistance than high CO/sub 2/ plants. Stomatal closure occurred at lower leaf water potentials for the low CO/sub 2/ grown plants than high CO/sub 2/ grown plants. Significantly greater starch concentrations were found in leaves of high CO/sub 2/ plants, and the reductions in leaf starch and increases in soluble sugars due to water stress were greater for low CO/sub 2/ plants. The results showed that even though greater growth was observed at high atmospheric CO/sub 2/ concentrations, lower rates of water use delayed and, thereby, prevented the onset of severe water stress under conditions of low moisture availability.

Research Organization:
North Carolina State Univ., Raleigh, NC (United States)
DOE Contract Number:
AI01-81ER60001
OSTI ID:
6598144
Journal Information:
Plant Physiol.; (United States), Vol. 74:2
Country of Publication:
United States
Language:
English