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海三棱藨草对极端高温的生长与生理响应

刘晓彤1,2,李秀珍1,2*,闫中正1,2,谢作轮1,2,林世伟1,2   

  1. 1华东师范大学河口海岸学国家重点实验室, 上海 200241;2华东师范大学崇明生态研究院, 上海 200241)
  • 出版日期:2020-01-10 发布日期:2020-01-10

Growth and physiological responses of Scirpus mariqueter to extremely high temperatures.

LIU Xiao-tong1,2, LI Xiu-zhen1,2*, YAN Zhong-zheng1,2, XIE Zuo-lun1,2, LIN Shi-wei1,2   

  1. (1StateKey Laboratory of Estuarine and Coastal Research, East China Normal University, Shanghai 200241, China; 2Institute of Eco-Chongming, East China Normal University, Shanghai 200241, China).
  • Online:2020-01-10 Published:2020-01-10

摘要: 在全球气候变化大背景下,极端气候事件频发,但目前关于盐沼植物对极端天气响应方面的研究极少。本研究以典型的河口盐沼植物海三棱藨草(Scirpus mariqueter)为对象,在温室内对其进行一周的不同高温(40、45、50 ℃)胁迫处理,研究其生长、生理及光合等参数的响应。结果表明:在受到45、50 ℃高温胁迫时,海三棱藨草的根冠比显著增高,生物量趋于向地下转移;叶绿素a、叶绿素b以及总叶绿素的含量随着温度的升高有下降的趋势,说明极端高温在一定程度上抑制了海三棱藨草体内叶绿素的合成;高温胁迫也对海三棱藨草生理上产生显著影响,其叶片和根中丙二醛含量均在受到45 ℃以上高温胁迫时显著降低,可能昭示着海三棱藨草有一定的耐热性;而脯氨酸含量在高温处理组(40~50 ℃)显著高于对照组(室温),可溶性糖含量表现为高温处理时(40~50 ℃)在叶中显著下降,在根中升高,表明海三棱藨草在高温胁迫时产生渗透调节物质积极抵抗逆境;海三棱藨草净光合速率在40 ℃处理时较对照组有所上升,而在45 ℃以上高温处理时显著下降,且伴随着气孔导度、胞间CO2浓度、蒸腾速率、羧化效率的下降,水分利用效率的升高,说明极端高温在一定范围内可促进光合作用,但超过一定程度会对海三棱藨草的光合作用产生抑制作用,也表明海三棱藨草高温胁迫下净光合速率的下降以气孔限制因素为主。本研究结果可为理解气候变化背景下盐沼植物对极端高温的适应机制提供参考依据。

关键词: 净初级生产力, 地上生物量, 空间格局

Abstract: Extreme weather events are becoming more and more frequent in the context of global climate change, but we know little about the responses of salt marsh plants to extreme weather conditions. In this study, a 7-day controlled greenhouse experiment was conducted to investigate the response of growth, physiology and photosynthetic parameters of Scirpus mariqueter, a typical estuary salt marsh plant species, to extremely high temperatures (40, 45, 50 ℃). Results showed that high temperature (45-50 ℃) significantly enhanced the root to shoot ratio of S. mariqueter and that more biomass was allocated to underground to cope with the damage induced by the high temperature. The content of chlorophyll a, chlorophyll b and total chlorophyll decreased with the increases of temperature, indicating that high temperature inhibited the synthesis of chlorophylls. High temperature stress affected the physiology of S. mariqueter, malondialdehyde content in leaves and roots decreased significantly when exposed to high temperature (45-50 ℃), which indicates that S. mariqueter has a certain heat tolerance. The content of proline was significantly higher in high temperature treatment (40-50 ℃) than in control, soluble sugar content decreased significantly in leaves and increased in roots, suggesting that the osmotic adjustment substances produced by S. mariqueterwere active in resisting stress. Compared with that in control, net photosynthesis rate of S. mariqueter increased at 40 ℃, but decreased significantly at 45 and 50 ℃, accompanied by the decreases of stomatal conductivity, intercellular CO2 concentration, transpiration rate, and water use efficiency, suggesting that photosynthesis rate of S. mariquetercan be promoted under a certain range of high temperature but be inhibited under extremely high temperature. Stomatal restriction was found to be the major limiting factor. Our results can provide a reference for understanding the adaptation mechanism of salt marsh plants to extremely high temperature in the context of climate change.

Key words: net primary productivity, spatial pattern., aboveground biomass