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Leaf Photosynthesis Water Use of Big Bluestem under Elevated Carbon Dioxide
Author(s) -
Kirkham M. B.,
He H.,
Bolger T. P.,
Lawlor D. J.,
Kanemasu E. T.
Publication year - 1991
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/cropsci1991.0011183x003100060042x
Subject(s) - transpiration , carbon dioxide , photosynthesis , water use efficiency , loam , canopy , growing season , agronomy , stomatal conductance , biology , soil water , horticulture , zoology , botany , ecology
With the atmospheric concentration of CO 2 increasing, it is importanto know how this will affect crop growth. The objective of the study was to determine the effect of elevated CO 2 on big bluestem ( Andropogon gerardii Vitman) growing in a tallgrass prairie on Tully silty clay loam (fine, mixed, mesic Pachic Argiustoll) kept a high water level (field capacity) or a low water level (half field capacity). Sixteen cylindrical plastic chambers were placed on the prairie to maintain the two levels of CO 2 (mean ± SD: 337 ± 32 and 658 ± 81 µmol mol ‐1 ) over a full growing season. Soil‐water content was measured weekly with a neutron probe. Photosynthesis, transpiration, stonmtal resistance, and intercellular CO 2 concentration were determined with a portable leaf photosynthetic system. Canopy temperature was monitored with an infrared thermometer. Elevated (doubled) CO 2 reduced transpiration rate of big binestem by 25 and 35% under the high‐ and low‐water treatments, respectively. Under both watering regimes, stomatal resistance was greater by ≈1.6 s cm ‐1 with doubled CO 2 than with ambient CO 2 . Plants grown with doubled CO 2 at high‐ and low‐water levels had warmer canopy temperatures (average 1.15 and 0.70 °C warmer, respectively) than plants grown ambient CO 2 . Carbon‐dioxide concentration did not affect the rate of photosynthesis, even though intercellular CO 2 concentration was increased under high CO 2 . Elevated CO 2 did not increase the height of plants grown at the high water level, but it did increase the height at the low water level by an average of 9 cm.