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

[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。

[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.