PJB-2017-318
Growth, physiological, and biochemical responses of three grass species to elevated carbon dioxide concentrations
Yunpu Zheng, Renqiang Li, Lihua Hao, Dongjuan Cheng, Haixia Wu, Fei Li, Lili Guo, Bingru Huang and Ming Xu
Abstract
The increased atmospheric CO2concentration may have profound impacts on the structure and function of grass land ecosystems, and the question that how C3grasseswill respond to a wider range of higher CO2 levels remains unanswered. Here, we exposed three widely distributed cool-season C3 grass species Tall fescue (Festuca arundinacea Schreb.), Perennial ryegrass (Lolium perenne L.), and Kentucky bluegrass (Poa pratensis L.) to ambient (400 μmol mol-1) or elevated CO2 concentrations (600, 800, 1000, and 1200 μmol mol-1) in growth chambers using an automatic CO2 controlling system. We examined growth, physiological, and biochemical responses to elevated CO2 with measurements on plant growth traits (relative growth rate and biomass), leaf gas exchange, and tissue biochemical composition (non-structural carbohydrates) of the three grass species during exposure to ambient or elevated CO2 concentrations for eight weeks. Our results showed that elevated CO2 concentrations significantly increased the averaged relative growth rates of Tall fescue and the total leaf area of Kentucky bluegrass. Meanwhile, CO2 enhancement significantly stimulated the leaf net photosynthesis rate(An) of the three species. However, both the area-based and N-based leaf dark respiration rates (Rd) of the three species were sharply decreased, and thus increased the ratio of leaf net photosynthesis and dark respiration. These results suggested that Tall fescue might be more responsive to elevated CO2in growth, physiological, and biochemical traits than the other two species, which has important implications for species composition, competition, and dynamics, and thus community structure and functionin natural and managed ecosystems under elevated CO2levels.
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