Elevated CO_plus-plus">2 increased photosynthesis and yield without decreasing stomatal conductance in broomcorn millet

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• 作者：X. Y. Hao ; P. Li ; H. Y. Li ; Y. Z. Zong ; B. Zhang ; J. Z. Zhao ; Y. H. Han
• 关键词：Additional key wordschlorophyll a fluorescence ; CO2 enrichment ; gas exchange ; water ; use efficiency
• 刊名：Photosynthetica
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：55
• 期：1
• 页码：176-183
• 全文大小：
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Plant Physiology;
• 出版者：The Institute of Experimental Biology of the Czech Academy of Sciences
• ISSN：1573-9058
• 卷排序：55

文摘

Broomcorn millet (Panicum miliaceum L.) is one of the important C₄ crops in the semiarid regions of northern China. It is a close relative of biofuel crop switchgrass. Yet, there is no information on how these crops might respond to a climate change in China. In order to gain insight into such a response, we studied the effect of elevated CO₂ concentration (EC) on broomcorn millet. The changes in leaf photosynthesis, chlorophyll fluorescence, morphological parameters, biomass and yield in response to EC [i.e., + 200 µmol(CO₂) mol−1] over two years were determined at the open-top chamber (OTC) experimental facility in north China. EC increased net photosynthetic rate, stomatal conductance, intercellular CO₂ concentration, transpiration rate, instantaneous transpiration efficiency, effective quantum yield of PSII photochemistry, and photochemical quenching coefficient of fully expanded flag leaves. Maximal quantum yield of PSII photochemistry declined under EC in 2013, but was not affected in 2014. EC significantly decreased intrinsic efficiency of PSII in 2013, but increased in 2014. Leaf nonphotochemical quenching decreased under EC both in 2013 and 2014. EC significantly enhanced the aboveground biomass and yield by average of 31.4 and 25.5% in both years, respectively. The increased yield of broomcorn millet under EC occurred due to the enhanced number of grains per plant. We concluded that photosynthesis of broomcorn millets was improved through increased stomatal conductance in leaves under EC, which led to an increase in height, stem diameter, aboveground biomass, and yield. This study extends our understanding of the response of this ancient C₄ crop to elevated CO₂ concentration.