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Climate change is affecting global crop productivity, food quality, and security. However,few studies have addressed the mechanism by which elevated CO_2 may affect the growth of medicinal plants. Isatis indigotica Fortune is a widely used Chinese medicinal herb with multiple pharmacological properties. To investigate the physiological mechanism of I.indigotica response to elevated [CO_2], plants were grown at either ambient [CO_2](385 μmol mol~(-1)) or elevated [CO_2] (590 μmol mol~(-1)) in an open-top chamber (OTC)experimental facility in North China. A significant reduction in transpiration rate (T_r) and stomatal conductance (g_s) and a large increase in water-use efficiency contributed to an increase in net photosynthetic rate (Pn) under elevated [CO_2] 76 days after sowing. Leaf non-photochemical quenching (NPQ) was decreased, so that more energy was used in effective quantum yield of PSII photochemistry (Φ_(PSⅡ)) under elevated [CO_2]. High ΦPSII,meaning high electron transfer efficiency, also increased Pn. The [CO_2]-induced increase in photosynthesis significantly increased biomass by 36.8%. Amounts of metabolic compounds involved in sucrose metabolism, pyrimidine metabolism, flavonoid biosynthesis, and other processes in leaves were reduced under elevated [CO_2]. These results showed that the fertilization effect of elevated [CO_2] is conducive to increasing dry weight but not secondary metabolism in I. indigotica.
However, few studies have addressed the mechanism by which elevated CO_2 may affect the growth of medicinal plants. Isatis indigotica Fortune is a widely used Chinese medicinal herb with multiple pharmacological properties. investigate the physiological mechanism of I.indigotica response to elevated [CO_2] plants were grown at either ambient [CO_2] (385 μmol mol -1) or elevated [CO_2] (590 μmol mol -1) in an open-top chamber (OTC) experimental facility in North China. A significant reduction in transpiration rate (T_r) and stomatal conductance (g_s) and a large increase in water-use efficiency contributed to an increase in net photosynthetic rate (Pn) under High non-photochemical quenching (NPQ) was decreased, so that more energy was used in effective quantum yield of PSII photochemistry (Φ_ (PSⅡ)) under elevated [CO_2]. High ΦPSII, meaning high electron tran [CO_2] -induced increase in photosynthesis increased significantly by 36.8%. Amounts of metabolic compounds involved in sucrose metabolism, pyrimidine metabolism, flavonoid biosynthesis, and other processes in leaves were reduced under elevated [CO_2] These results showed that the fertilization effect of elevated [CO_2] is conducive to increasing dry weight but not secondary metabolism in I. indigotica.