Knowledge Resource Center for Ecological Environment in Arid Area
| 水、盐梯度下长穗柽柳和梭梭光合响应及同位素组成变化特征 | |
| 其他题名 | Effects of water availability and salinity on photosynthetic features and isotopic composition in Tamarix elongata and Haloxylon ammodendron |
| 闵孝君 | |
| 出版年 | 2016 |
| 学位类型 | 硕士 |
| 导师 | 马剑英 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 在干旱和半干旱地区，水分是植物生长和繁殖的首要限制因素。全球变化背景下，未来降水模式会发生改变，干旱事件的频次和强度呈增加趋势。干旱和半干旱区水分亏缺和盐渍化通常同时存在，降水模式的改变必然影响土壤盐分的运移，高温、干旱和/或高盐度可能改变不同光合类型植物在植被组成中的比例，进而影响干旱区荒漠生态系统的结构和功能。了解干旱和盐胁迫下不同光合类型荒漠植物的响应特征、水分适应策略和抗性机制，对预测干旱区气候变化下荒漠生态系统的植被组成和功能具有重要的理论意义。本研究选择新疆荒漠优势种C3植物长穗柽柳（Tamarix elongata Ledeb）和C4植物梭梭[Haloxylon ammodendron (C.A.Mey.) Bunge]一年生幼苗为实验材料，研究了不同水和NaCl处理下长穗柽柳和梭梭叶片气体交换、水势、离子浓度和碳、氮同位素组成等变化特征。主要研究结果如下：（1）盐度增加显著减小了梭梭和长穗柽柳叶水势。水分降低也明显减小两者水势。所有处理下梭梭平均水势小于长穗柽柳平均叶水势。然而，梭梭平均叶片含水量却大于长穗柽柳平均叶片含水量。梭梭同化枝含水量在盐处理下显著增加，而长穗柽柳叶片含水量随盐度增加而减小；（2）高盐度下，梭梭和长穗柽柳光合作用速率（A）、气孔导度（gs）、蒸腾速率（T）均明显下降，干旱处理也有相似趋势。高盐度下，梭梭和长穗柽柳叶绿素含量显著下降。干旱胁迫下，梭梭叶绿素含量减小但是长穗柽柳的变化不显著；（3）梭梭和长穗柽柳的叶片碳同位素组成（δ13C）与盐度呈正相关；干旱处理下长穗柽柳δ13C值随水分降低显著增大，而梭梭变化不显著。叶片氮同位素组成（δ15N）与盐度呈负相关关系；干旱胁迫下，两种植物叶片δ15N值均显著减小。此外，2个月与1个月时间处理对比，梭梭δ13C值随着处理时间的增长而减小，而长穗柽柳δ13C值随着处理时间的增长却增大；随着处理时间的增长，梭梭15N含量增加而长穗柽柳15N含量则减少。可能由于2个月处理后，梭梭表现出一定的适应性，而长穗柽柳则没有；（4）高盐处理下，梭梭和长穗柽柳叶片C含量和N含量均显著减小；梭梭C:N随盐度增加而增加，长穗柽柳则相反。随着盐度增加，两种植物叶片的Na＋离子浓度增加而K＋离子浓度减小，可能Na＋离子主要参与了渗透调节作用；（5）梭梭和长穗柽柳的δ13C值与水势、叶绿素含量、gs、T和C:N显著相关，因此δ13C值可以作为两者胁迫条件下的良好指标。 本研究表明，在干旱和盐度环境下，C4植物梭梭比C3植物长穗柽柳具有更强的适应性。梭梭和长穗柽柳这两种不同光合作用类型植物的耐盐和耐旱机理不同，梭梭主要通过离子渗透作用维持体内正常水分平衡，而长穗柽柳则通过叶表面盐腺把多余的盐排出体外。叶片δ13C值与植物多种生理指标相关，对植物受环境胁迫程度有较好的指示作用。 |
| 英文摘要 | Water is the primary limiting factor for plant growth and reproduction in arid and semiarid regions. With the intensification of global climate change, precipitation pattern(amount and timing) are likely to be altered with, drought events are predicted to be increased in both frequency and intensity. Water deficit and salinization usually occur together, which have been observed not only in farmland ecosystems but also in natural ecosystems. Salinization and migration of soil salts are likely to be influenced by the changes in preciption regime. Heat, drought and/or high salinity may alter C3 and C4 plants differently and change their proportion in vegetation composition. Therefore, understanding plant photosynthetic type differences in response features, water adaptive strategies and resistance mechanisms to drought and salinity stress, plays a important theoretical significance for the prediction of vegetation composition and ecosystem function in future climate change. For this study, we measured gas exchange, water potential, ion content and carbon and nitrogen isotopic composition under different water and NaCl trearments in the saplings of two dominant woody species in western China, C3 plant Tamarix elongata Ledeb and C4 plant Haoxylon ammodendron (C. A. Mey.) Bunge. The results are as follows:(1) Lower water potential values were measured in H. ammodendron and T. elongata under both high salinity and drought treatments. T. elongata had higher mean water potential compared to H. ammodendron under all treatments. However, mean water content in H. ammodendron was greater than T. elongata. Leaf water content in H. ammodendron under the control treatment was smaller than under the salinity treatment, whereas leaf water content in T. elongata decreased with the salinity treatment. (2)The salinity treatment caused significant reductions in photosynthetic rate (A), stomatal conductance (gs) and transpiration rate (T), similar patterns were also observed with the drought treatment. The salinity treatment reduced chlorophyll content in both H. ammodendron and T. elongata, whereas the drought treatment resulted in a significant reduction in chlorophyll content in H. ammodendron but not in T. elongata. (3) For the two studied plants, there were positive correlations between carbon isotopic composition (δ13C) and salinity. The drought treatment induced an increase in δ13C values in T. elongata but had no significant effects on δ13C in H. ammodendron. Lower nitrogen isotopic composition (δ15N) values were detected under both salinity and drought treatments. In addition, δ13C and δ15N were influenced by the duration of salinity and drought treatments, δ13C values in H. ammodendron were reduced over time, whereas δ13C values in T. elongata were increased. With the extension of treatment time, 15N in H. ammodendron was enriched while 15N in T. elongata was depleted. These results suggest H. ammodendron adapted quicker than T. elongata to manipulated changes in environmental stresses. (4) Leaf carbon and nitrogen content in H. ammodendron and T. elongata were significantly decreased under the high salinity treatment. With increasing salinity, C:N ratio in H. ammodendron gradually increased; whereas C:N ratio showed a pattern of decreasing in T. elongata. Leaf Na+ concentration increased and K+ concentration decreased with the intensification of the salinity treatment in the two studied species. The observed enhancement in Na+ concentration may be an adapting mechanism associated with osmosis regulation. (5) We observed significant correlations between δ13C values and water potential, chlorophyll content, gs, T, C:N and Na/K; therefore δ13C values could be used as a robust indicator of the intensity of drought and salinity stress. The results of this study indicated that C4 plant H. ammodendron adapt quickly to drought and salinity stress than C3 plant T. elongata. The studied plants used different strategies to cope with salinity and drought stress; H. ammodendron mainly maintains normal water balance in vivo via regulating ion osmosis, whereas T. elongata secretes redundant salt through salt glands from leaf surface. Leaf δ13C values are well related with various plant physiological parameters and can be used to reflect levels of plant environmental stress. |
| 中文关键词 | 不同光合类型 ; 荒漠植物 ; 水盐胁迫 ; 碳氮稳定同位素 |
| 英文关键词 | Photosynthetic pathway desert plant Drought and salt stress Carbon and nitrogen stable isotopes |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 生物工程 |
| 来源机构 | 中国科学院新疆生态与地理研究所 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287776 |
| 推荐引用方式 GB/T 7714 | 闵孝君. 水、盐梯度下长穗柽柳和梭梭光合响应及同位素组成变化特征[D]. 中国科学院大学,2016. |
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