Responses of legume versus nonlegume tropical tree seedlings to elevated CO2 concentration

Journal Publication ResearchOnline@JCU
Cernusak, Lucas A.;Winter, Klaus;Martínez, Carlos;Correa, Edwin;Aranda, Jorge;Garcia, Milton;Jaramillo, Carlos;Turner, Benjamin L.
Abstract

We investigated responses of growth, leaf gas exchange, carbon-isotope discrimination, and whole-plant water-use efficiency (WP) to elevated CO2 concentration ([CO2]) in seedlings of five leguminous and five nonleguminous tropical tree species. Plants were grown at CO2 partial pressures of 40 and 70 Pa. As a group, legumes did not differ from nonlegumes in growth response to elevated [CO2]. The mean ratio of final plant dry mass at elevated to ambient [CO2] (ME/MA) was 1.32 and 1.24 for legumes and nonlegumes, respectively. However, there was large variation in ME/MA among legume species (0.92–2.35), whereas nonlegumes varied much less (1.21–1.29). Variation among legume species in ME/MA was closely correlated with their capacity for nodule formation, as expressed by nodule mass ratio, the dry mass of nodules for a given plant dry mass. WP increased markedly in response to elevated [CO2] in all species. The ratio of intercellular to ambient CO2 partial pressures during photosynthesis remained approximately constant at ambient and elevated [CO2], as did carbon isotope discrimination, suggesting that WP should increase proportionally for a given increase in atmospheric [CO2]. These results suggest that tree legumes with a strong capacity for nodule formation could have a competitive advantage in tropical forests as atmospheric [CO2] rises and that the water-use efficiency of tropical tree species will increase under elevated [CO2].

Journal

Plant Physiology

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Volume

157

ISBN/ISSN

1532-2548

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Issue

1

Pages Count

14

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Publisher

American Society of Plant Biologists

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DOI

10.1104/pp.111.182436