Influence of Elevated CO2 Concentration and Nitrogen Source on Photosynthetic Traits in the Invasive Species Eupatorium adenophorum (Asteraceae) |
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Authors: | OUYANG-Fen ZHENG Guo-Wei LI Wei-Qi |
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Institution: | 1.Germplasm Bank of Wild Species in Southwest China, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming 650201, China;2.University of Chinese Academy of Sciences, Beijing 100049, China;3.Biology Department, Honghe University, Mengzi 661100, China |
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Abstract: | Increases in the concentration of atmospheric CO2 and plant invasion are two important problems that face humans worldwide. In some plants, exposure to a short term elevated concentration of CO2 (SE[CO2]) promotes photosynthesis, but the promotion of elevated [CO2] (E [CO2]) to photosynthesis might disappear after long term treatment (so called “CO2 acclimation”); this might result from the associated inhibition of nitrate assimilation. The present study investigated the physiological effects of short term (8 days) and long term (40 days) exposure to E[CO2] when these were combined with different forms of inorganic N (full N; nitrate (NO3-) N) in the invasive species Eupatorium adenophorum. Exposure to E[CO2] increased the biomass of Eadenophorum, regardless of the duration of exposure to E[CO2] and the type of inorganic N that was supplied. E[CO2] could promote the photosynthesis of Eadenophorum seedlings fertilised with non depleted Hoagland solutions (full N). For plants fertilised with NH4+ depleted Hoagland solution (NO3- N), LE[CO2] treatment promoted the photosynthesis of Eadenop horum, but the promotion of photosynthesis by E[CO2] disappeared under SE[CO2] conditions. Photosynthetic pigments contents were determined to estimate potential changes in the photosynthetic capacity of Eadenophorum. For plants fertilised with non depleted Hoagland solution, there were no significant differences in chlorophyll among the three [CO2] treatments, but the treatment of SE[CO2] increased the levels of chlorophyll in leaves. The apparent promotion of biomass accumulation and photosynthesis at LE[CO2] without a decrease in chlorophyll indicates that Eadenophorum might not acclimate to long term exposure to E[CO2]. NH4+ depletion did not affect the capacity of LE[CO2] to promote the photosynthesis of Eadenophorum. Thus, considering some plants fertilised with NO3- acclimating to LE[CO2], Eadenophorum might be more competitive in areas where the soils are relatively poor in NH4+ as levels of atmospheric CO2 continue to rise. |
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Keywords: | Elevated CO2 Eadenophorum Invasive plants Photosynthesis acclimation NO3- assimilation |
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