Leaf and plant water use efficiency of C{sub 4} species grown at glacial to elevated CO{sub 2} concentrations
- USDA, Temple, TX (United States)
Leaf gas exchange was measured on C{sub 4} plants grown from near glacial to current CO{sub 2} concentrations (200-350 {mu}mol mol{sup -1}) and from the current concentration to possible future levels (near 700 and 1000 {mu}mol mol{sup -1}) to test the prediction that intrinsic water use efficiency (CO{sub 2} assimilation [A]/stomatal conductance to water [g]) would rise by a similar relative amount as CO{sub 2} concentration. Studied were species differing in growth form or life history, the perennial grass Schizachyrium scoparium (little bluestem), perennial shrub Atriplex canescens (four-wing saltbush), and annual grass Schizachyrium scoparium (little bluestem), leaf A/g of the C{sub 4} species examined was stimulated proportionally more by a given relative increase in CO{sub 2} over subambient than by elevated concentrations. The ratio of the relative increase in A/g to that in CO{sub 2} exceeded unity in S, scoparium and A. canescens as CO{sub 2} rose from 700 to 1000 {mu}mol mol{sup -1}. At higher CO{sub 2} concentrations, A/g of the C{sub 4} perennials was similar to that expected for C{sub 3} plants. Since much of the potential response of C{sub 4} plants to CO{sub 4} perennials was similar to that expected for C{sub 3} plants. Since much of the potential response of C{sub 4} plants to CO{sub 2} often derives from higher water use efficiency (WUE), these results indicated that potential productivity of some C{sub 4} plants increased relatively more since glaciation than it will in the future. There also were large (>100%) differences in A/g and plant WUE (production/transpiration) at a given CO{sub 2} level among the plants examined that could influence the relative productivities of C{sub 4} species or growth forms and their interactions with C{sub 3} plants. 34 refs., 3 figs., 3 tabs.
- OSTI ID:
- 379416
- Journal Information:
- International Journal of Plant Sciences, Vol. 157, Issue 2; Other Information: PBD: Mar 1996
- Country of Publication:
- United States
- Language:
- English
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