Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.
Lancaster Environment Centre, Lancaster University, Lancaster, UK.
J Exp Bot. 2019 Mar 11;70(5):1567-1580. doi: 10.1093/jxb/ery462.
Life history and photosynthetic type both affect the economics of leaf physiological function. Annual plants have lower tissue densities and resource-use efficiencies than perennials, while C4 photosynthesis, facilitated in grasses by specific changes in leaf anatomy, improves photosynthetic efficiency and water-use efficiency, especially in hot climates. This study aimed to determine whether C4 photosynthesis affects differences in functional traits between annual and perennial species. We measured 26 traits and characterised niche descriptors for 42 grasses from subtropical China. Differences in the majority of traits were explained by life history. The ranges of annual species (particularly C4 annuals) extended to regions with greater temperature seasonality and lower precipitation, and annuals had less-negative turgor-loss points, higher specific leaf areas, and lower water-use efficiencies, stomatal conductances, and leaf areas per stem area than perennials. Photosynthetic type largely affected leaf physiology as expected, but interacted with life history in determining specific traits. Leaf hydraulic conductance was intermediate in perennials, highest in C4-annuals, and lowest in C3-annuals. Densities of stomata and stem vessels were similar across C3-perennials and C4 species, but stomatal densities were lower and stem vessel densities higher in C3-annuals. Phylogenetic principal component analysis confirmed that in this subtropical environment life history is the predominant axis separating species, and annuals and perennials were more different within C3 than C4 grasses. The interplay between life history and photosynthetic type may be an overlooked factor in shaping the physiological ecology of grasses.
生活史和光合作用类型都会影响叶片生理功能的经济性。与多年生植物相比，一年生植物的组织密度和资源利用效率较低，而 C4 光合作用通过叶片解剖结构的特定变化在禾本科植物中得到促进，提高了光合作用效率和水分利用效率，特别是在炎热的气候条件下。本研究旨在确定 C4 光合作用是否会影响一年生和多年生物种之间功能特征的差异。我们测量了来自中国亚热带地区的 42 种禾本科植物的 26 个特征，并描述了它们的生态位描述符。大多数特征的差异是由生活史决定的。一年生物种（特别是 C4 一年生植物）的范围扩展到温度季节性更强、降水更低的地区，而且一年生植物的膨压丧失点的负值较小、比叶面积较大、水分利用效率、气孔导度和茎面积比叶面积较低。与预期的一样，光合作用类型主要影响叶片生理学，但在确定特定特征时与生活史相互作用。叶片水力传导率在多年生植物中处于中间水平，在 C4-一年生植物中最高，在 C3-一年生植物中最低。C3-多年生植物和 C4 物种的气孔密度和茎导管密度相似，但 C3-一年生植物的气孔密度较低，茎导管密度较高。系统发育主成分分析证实，在这种亚热带环境中，生活史是区分物种的主要轴线，一年生植物和多年生植物在 C3 类植物中的差异大于 C4 类植物。生活史和光合作用类型之间的相互作用可能是塑造禾本科植物生理生态的一个被忽视的因素。
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