Journal of Plant Ecology ›› 2023, Vol. 16 ›› Issue (4): 0-rtac108.DOI: 10.1093/jpe/rtac108

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  • 收稿日期:2022-06-16 修回日期:2022-07-10 接受日期:2022-12-13 出版日期:2023-08-01 发布日期:2022-12-26

Leaf traits of clonal grasses responding to the ratios of ammonium to nitrate in a semi-arid grassland: leaf order matters

Ruoxuan Liu1,2, Jungang Chen1, Zhengru Ren1,2, Xu Chen1,2, Haining Lu1,2, Yuqiu Zhang1,2, Yunhai Zhang1,2,*   

  1. 1State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China;
    2University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2022-06-16 Revised:2022-07-10 Accepted:2022-12-13 Online:2023-08-01 Published:2022-12-26
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摘要: 叶片是植物光合作用的主要器官。叶片可塑性在很大程度上决定了植物对富氮环境的适应。然而在自然条件和富氮环境中,测定植物叶片性状时需要采集的最佳数量或比例是否一致并不明确;同时大气氮沉降主要组分铵态氮与硝态氮比例变化是否会改变叶片最佳测量数量缺少实验证据支撑。因此本研究依托自2014年在中国北方温带草原开展的铵硝比添加实验(即对照和5:1、1:1和1:5的NH4+-N/NO3--N比例),于2020年8月(植物群落生物量高峰时期)测量了两个形态相似的优势多年生禾本科物种(即羊草和冰草)在叶序水平的叶面积、叶厚度和叶绿素含量。我们发现在对照处理(自然条件),除羊草叶面积需要测定5片(占单株总叶片数的78.82%),其它性状通过测量两片完全展开叶即可代表整株该叶性状的单叶平均特征。铵硝比添加处理显著改变了叶性状最大值所在叶序,导致需要增加叶片测定数才能代表整株叶片的单叶平均特征。铵硝比添加显著改变了受叶序调控的叶性状间权衡关系,即叶片虽变大却变薄。因此,本研究结果表明,通过测量全部完全展开叶或者提供一个合适的尺度推绎参数方能更好地评估氮沉降效应下植株叶片性状的响应特征。

关键词: 物种共存, 叶龄, 氮素形态, 光合能力, 植物功能性状, 权衡策略

Abstract: Leaf is the main organ of photosynthesis. Leaf phenotypic plasticity largely determines the adaptation of plants to enriched nitrogen (N) environments. However, it remains unclear whether the optimal number (proportion) of leaves representing the leaf traits of the whole plant is similar between ambient and N-enriched conditions. Moreover, whether alteration in ammonium (NH4+-N) to nitrate (NO3--N) ratios in atmospheric N deposition will alter the optimal leaf number is unexplored. By adding three NH4+-N/NO3--N ratios in a temperate grassland of northern China since 2014, three traits (leaf area, thickness and chlorophyll content) of two dominant clonal grasses, Leymus chinensis and Agropyron cristatum, were measured in August 2020. Results showed that under ambient conditions, the mean leaf area, thickness and chlorophyll content values of two fully expanded leaves were similar to these of all leaves at the plant level, except for the leaf area of L. chinensis, which needed five leaves (78.82% of leaves in the plant). The ratios of NH4+-N/NO3--N increased the number of required sampled leaves and significantly changed the mean value of leaf traits and the maximum value along leaf order. Moreover, the ratios of NH4+-N/NO3--N altered the trade-off among the three leaf traits, which is dependent on leaf order, by increasing leaf area and decreasing leaf thickness. Therefore, our study suggests that to better indicate the leaf traits’ value of the whole plant under N-enriched conditions, measuring all fully expanded leaves or providing a suitable scaling-up parameter is needed.

Key words: coexistence, leaf age, nitrogen form, photosynthetic capacity, plant functional trait, trade-off strategy