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2019年,三峡水库已连续10 a完成175 m蓄水目标。年复一年的季节性水位涨落形成30 m的消落带区域,是水生生态系统和陆生生态系统交替存在的特殊地带 (图1)[1]。冬季的完全水淹和夏季的伏旱使消落区植被物种多样性呈下降趋势,水土流失较突出[2]。重新造林和植被重建是恢复这些新形成的河岸带的首要任务[3]。因此,筛选出能长期遭受水淹并能正常生长的植物十分重要。目前,与草本植物相比,在长期淹水中能够存活的木本植物相对较少,尤其是完全淹没的品种[4-5]。水桦(Betula nigra L.),属桦木科(Betulaceae)落叶乔木,树高18~25 m,具有抗病虫、抗寒、耐水淹、抗污染等特性[6]。三峡库区良木水桦(良种编号:渝R-ETS-BN-007-013)为重庆市林业科学研究院引自美国的树种[7],研究表明,消落带中高程170 m处生长的水桦光合作用略强于高程175 m处,说明水桦可通过增强生长期的光合能力一定程度上补偿冬季蓄水对生长的负面影响,是三峡库区消落带植被恢复重建的适生树种[7]。当前,万州区消落带示范区水桦定植后已有5 a,以时间为轴的形态与生理生化指标变化等未见报道。本研究以三峡库区消落带溪口乡栽培的水桦为研究对象,调查水桦在经历周期性水淹后的生理指标的变化及解剖结构的恢复动态,为水桦的扩大栽培与品种选育提供理论依据。
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与对照组相比,在消落区栽植并经历水淹,对水桦株高有较大影响,水淹1次后株高有近70 cm的停滞生长,水淹2次后株高与对照仍有差异,水淹3次后,株高与对照没有差异,水淹5次后,株高比对照增加,并且差异显著。从胸径看,水淹1次后与对照差异不显著,水淹2次和3次后的水桦,胸径与对照均差异显著,水淹4次以后与对照差异不显著。总体可见,水桦在消落区定植后第1年株高受抑制,第2年和第3年胸径受抑制,经过3 a的适应后,植株顶端不再被完全淹没,生长基本不再受影响,并且在第5年开始有了较强的生长补偿效应 (表1、图2)。
表 1 消落带水桦周期性水淹后的形态指标的变化
Table 1. Changes of morphological indexes of Betula nigra after periodic flooding in the depression zone
处理
Treatment树高
Tree height/m胸径
DBH/cm水淹-1 1.52 ± 0.16 g 7.52 ± 1.68 d CK-1 2.27 ± 0.23 f 8.16 ± 2.14 d 水淹-2 2.35 ± 0.25 f 9.36 ± 2.22 d CK-2 2.79 ± 0.32 e 12.81 ± 2.08 c 水淹-3 3.56 ± 0.47 d 12.35 ± 3.18 c CK-3 3.88 ± 0.28 d 14.29 ± 5.16 b 水淹-4 6.59 ± 0.61 c 16.46 ± 4.28 b CK-4 7.04 ± 0.88 fc 18.61 ± 6.32 b 水淹-5 11.26 ± 1.27 a 20.52 ± 3.19 a CK-5 9.90 ± 1.38 b 19.56 ± 7.12 a 注:同列不同字母表示不同处理间差异显著(p < 0.05)。下同。
Note: Between different treatment groups (P < 0.05). The same below. -
图3A表明:随树龄增加水桦叶片中的含水量逐步降低,水淹1次后的植株叶片含水量相比对照有显著升高,水淹2次后与对照叶片含水量显著不差异。水桦叶片叶绿素含量变化主要在第1次水淹后,叶绿素a含量(图3B)、总叶绿素(图3C)和叶绿素a/b(图3D)与对照相比均呈显著下降趋势。水淹2次后植株的这4个指标与对照相比再无差异;水淹3次后,水淹和对照植株叶片的叶绿素a含量、总叶绿素含量和叶绿素a/b均显著高于1~2次水淹。说明随着水淹次数的增加,水桦的适应性逐步建立,退水后刺激植物加速生长,叶绿素含量相应的增多,进而增加了水桦叶片的光合强度,生长能力也逐步恢复。
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图4A表明:水桦叶片中可溶性蛋白含量比根中高,水淹1次和2次后的水桦叶片中可溶性蛋白含量都比对照高,水淹3次后与对照组不再有差异;根系中的可溶性蛋白质含量前3次水淹后均高于对照,水淹4次后,与对照差异不显著。图4B表明:与对照组相比,水淹1次和2次后叶片和根系中的丙二醛含量显著增加,水淹3次后差异不显著。图4C表明:第1次水淹后叶片中的SOD活性显著高于对照,2次水淹后与对照差异不显著;根系中的SOD活性在2次水淹后显著高于对照,水淹3次后,与对照差异不显著。水桦在水分胁迫时积累较多的渗透调节物质和抗氧化酶等来积极应对水分逆境,经过周期性水淹后的积累量和代谢速度都有差异,经历1~2次水淹后,在恢复过程中这类物质消除比较慢,在出水后的叶片和根系中都能检测到,相对来说,根系的胁迫敏感和持久性比叶片更明显,3次水淹后水桦的几项生理指标基本上与对照没有显著差异,说明耐水淹的适应机制基本建立,这估计与第3次以后的水淹只是半淹的条件有关。
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水桦为典型的两面叶植物,叶片有明显的上表面和下表面之分,有表皮细胞,栅栏组织2层,海绵组织多层,其中,分布有维管束(图5)。周期性水淹次数对水桦叶形态和组织结构均有显著的影响,水分胁迫改变了水桦叶片的组织结构及比例,水淹1~2次后,叶片上表皮(EP)均比未水淹厚,栅栏组织(PT)发达,排列紧密;3次水淹后的植株叶片与对照没有明显的结构差异,特别是经历4次水淹后,植物叶片气孔窝密度增加,叶片海绵细胞间隙增大,与对照没有差异。
图 5 消落带水桦周期性水淹后的叶片横切面结构变化
Figure 5. Changes of cross section structure of Betula nigra leaves in the ebb zone after periodic flooding
图6表明:水淹2次后,维管束中间导管(CA)细胞变大,细胞松散,水淹4次后,木质部与韧皮部之间出现了一些较大空隙的溶生型组织,能够更好的适应呼吸和代谢。
三峡库区消落带水桦(Betula nigra)周期性水淹后的生理与结构响应
Physiological and Structural Responses of Betula nigra to Periodic Flooding in Three Gorges Reservoir Fluctuating Zone
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摘要:
目的 探究消落带植物水桦(Betula nigra)水淹后的生理响应,为消落带进行植物修复提供重要依据。 方法 以三峡库区消落带万州段溪口乡示范带为试验地点,对比172 m高程、经历1~5次周期性水淹的水桦其生长指标、生理指标及解剖结构。 结果 水桦苗在消落区栽植后,周期性水淹5次后与对照相比株高有增加趋势,胸径没有差异;水淹2次后叶片含水量和对照组差异不显著;水淹3次后叶片叶绿素含量与对照差异不显著;水淹1~2次后,水桦叶片中可溶性蛋白含量都比对照要高,水淹3次后与对照差异不显著,根系中是水淹4次后与对照差异不显著;水淹1次和2次后叶片和根系中丙二醛含量与对照相比都显著增加,水淹3次后无差异;水淹1次后叶片中SOD比对照增加,水淹2次后差异不显著,根系中是水淹3次后差异不显著;解剖结构表明水淹后叶片上表皮增厚,栅栏组织发达,排列紧密,经历4~5次水淹后,叶片海绵组织细胞间隙增大,形成较大的气孔窝,叶片维管束的木质部与韧皮部之间出现了一些较大空隙的溶生型组织。 结论 万州区消落带172 m高程栽植的水桦在间歇性半水淹的条件下产生了较为明显的补偿效应,在水淹3次后已经具备了较好的适应能力,这为水桦在消落区更低高程环境下生存以及苗木的选育提供基础数据。 Abstract:Objective To study the physiological responses of Betula nigra in fluctuating zone to flooding in order to support the phytoremediation. Method Taking Xikou Township, which is located at the fluctuating zone of Wanzhou Section of the Three Gorges Reservoir Area, as the experimental site, the growth index, physiological index and anatomical structure of B. nigra, which experienced one to five times of flooding, were compared to study the response of B. nigra to periodic flooding. Result The results showed that the height of B. nigra seedlings tended toward increase after 5 times of flooding, but there was no difference in DBH. The leaf water content and the CK were no longer different after two times of flooding; the leaf chlorophyll content a, total chlorophyll and chlorophyll a/b were no longer changed after three times of flooding. After one to two times of flooding, the content of soluble protein in B. nigra leaves was higher than that in CK. After three times of flooding, there was no difference between birch leaves and the CK. After four times of flooding, there was no difference between B. nigra roots and the CK. The MDA content in leaves and roots increased significantly after one and two times of flooding compared with that in CK, and there was no difference after three times of flooding. The SOD content in leaves increased after the first time of flooding compared with the CK, and there was no difference after two times of flooding. There was no difference of SOD content in roots after three times of flooding. The anatomical structure showed that the upper epidermis of the leaves was thickened after flooding, and the palisade tissue was developed and arranged closely. After four to five times of flooding, the cell gap of the spongy tissue of the leaves increased, forming large stomatal fossa, and some dissolved tissue with large gap appeared between the xylem and phloem of the vascular bundle of the leaves. Conclusion The B. nigra planted at the elevation of 172 m in the fluctuating zone of Wanzhou District has produced a more obvious compensation effect under the condition of intermittent semi-flooding. It has already had a good adaptability after three times of flooding. -
Key words:
- Three Gorges Reservoir area
- / fluctuating zone
- / Betula nigra
- / flooding stress
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表 1 消落带水桦周期性水淹后的形态指标的变化
Table 1. Changes of morphological indexes of Betula nigra after periodic flooding in the depression zone
处理
Treatment树高
Tree height/m胸径
DBH/cm水淹-1 1.52 ± 0.16 g 7.52 ± 1.68 d CK-1 2.27 ± 0.23 f 8.16 ± 2.14 d 水淹-2 2.35 ± 0.25 f 9.36 ± 2.22 d CK-2 2.79 ± 0.32 e 12.81 ± 2.08 c 水淹-3 3.56 ± 0.47 d 12.35 ± 3.18 c CK-3 3.88 ± 0.28 d 14.29 ± 5.16 b 水淹-4 6.59 ± 0.61 c 16.46 ± 4.28 b CK-4 7.04 ± 0.88 fc 18.61 ± 6.32 b 水淹-5 11.26 ± 1.27 a 20.52 ± 3.19 a CK-5 9.90 ± 1.38 b 19.56 ± 7.12 a 注:同列不同字母表示不同处理间差异显著(p < 0.05)。下同。
Note: Between different treatment groups (P < 0.05). The same below. -
[1] 朱妮妮, 秦爱丽, 郭泉水, 等. 三峡水库巫山—秭归段典型消落带植被空间分异研究[J]. 林业科学研究, 2015, 28(1):109-115. [2] Yang S L, Zhang J, Dai S B, et al. Effect of deposition and erosion within the main river channel and large lakes on sediment delivery to the estuary of the Yangtze River[J]. Journal of Geophysical Research Earth Surface., 2007, 112(F2): 111-119. [3] Yang F, Liu WW, Wang J, et al. Riparian vegetation’s responses to the new hydrological regimes from the Three Gorges Project: Clues to revegetation in reservoir waterlevel-fluctuation zone[J]. Acta EcologicaSinica, 2012, 32: 89-98. [4] 罗 祺, 张纪林, 郝日明, 等. 水淹胁迫下10个树种某些生理指标的变化及其耐水淹能力的比较[J]. 植物资源与环境学报, 2007, 16(1):69-73. doi: 10.3969/j.issn.1674-7895.2007.01.016 [5] Yu X, Luo N, Yan J, et al. Differential growth response and carbohydrate metabolism of global collection of perennial ryegrass accessions to submergence and recovery following de-submergence[J]. Journal of Plant Physiology, 2012, 169(11): . 1040-1049. doi: 10.1016/j.jplph.2012.03.001 [6] 高 岚, 刘 芸, 熊兴政, 等. 引种植物水桦与乡土植物桑树对三峡库区消落带水淹的响应[J]. 林业科学, 2018, 54(9):147-156. doi: 10.11707/j.1001-7488.20180917 [7] 袁贵琼, 刘 芸, 邬静淳, 等. 模拟三峡库区消落带水淹对3类土壤中桑树和水桦生长的影响[J]. 西北农林科技大学学报: 自然科学版, 2018, 46(6):65-74. [8] Grace S C, Logan B A. Acclimation of foliar antioxidant systems to growth irradiance in three broad-leaved evergreen species[J]. Plant Physiol, 1996, 112(4): 1631-1640. doi: 10.1104/pp.112.4.1631 [9] 李小方, 张志良. 植物生理学实验指导[M]. 北京: 高等教育出版社, 2016. [10] 李和平. 植物显微技术[M]. 北京: 科学出版社, 2009. [11] 刘玉芳, 陈双林, 郭子武, 等. 淹水对河竹鞭根系统生物量分配及异速生长模式的影响[J]. 林业科学研究, 2018, 28(4):29-36. [12] Burkett V R, Draugelis-Dale R O, Williams H M, et al. Effects of flooding regime and seedling treatment on early survival and growth of nuttall oak[J]. Restoration Ecology, 2005, 13(3): 471-479. doi: 10.1111/j.1526-100X.2005.00059.x [13] 黄秋婵, 韦友欢. 阳生植物和阴生植物叶绿素含量的比较分析[J]. 湖北农业科学, 2009, 48(8):1923-1924, 1929. doi: 10.3969/j.issn.0439-8114.2009.08.039 [14] Kumutha D, EzhilmathiK, Sairam R K, et al. Waterlogging induced oxidative stress and antioxidant activity in pigeonpea genotypes[J]. Biologia Plantarum, 2009, 53(1): 75-84. doi: 10.1007/s10535-009-0011-5 [15] 陈丽英, 杜克兵, 姜法祥, 等. 水淹胁迫对2种杨树初生根细胞结构的影响[J]. 林业科学, 2015, 51(3):163-169. [16] 胡潇予, 于海燕, 崔艺凡, 等. 不同种源文冠果叶片气孔分布特征对水分胁迫的响应[J]. 林业科学研究, 2019, 32(1):169-174. [17] 李芳兰, 包维楷. 植物叶片形态解剖结构对环境变化的响应与适应[J]. 植物学通报, 2005, 22(增刊):118-127. [18] Colmer T D, Cox M C H, Voesenek L A C J. Root aeration in rice(Oryza sativa): evaluation of oxygen, carbon dioxide and ethyleneas possible regulators of root acclimatizations[J]. New Phytologist, 2006, 170(4): 767-778. doi: 10.1111/j.1469-8137.2006.01725.x [19] Kawase M. Anatomical and morphological adaption of plants towaterlogging[J]. Hort. Science, 1981, 16: 8-12. [20] Phukan U J, Mishra S, Shukla R K. Waterlogging and submergence stress: affects and acclimation[J]. Critical Reviews in Biotechnology, 2016, 36(5): 956-966. doi: 10.3109/07388551.2015.1064856