露天煤矿排土场土层重构及接菌对植物根系提水作用试验研究

Experimental study on effect of soil layer reconstruction and inoculation on plant root hydraulic lift in open-pit coal mine dump

露天煤矿排土场土层重构对于生态重建具有重要意义,为研究接种深色有隔内生真菌(dark septate endophytes,DSE)对不同重构土层模式下玉米根系水分的利用效应,采用土柱模拟培养试验,设置4种类型土层处理,每种土层类型下设置接菌及对照处理,共8组处理。结果表明:掺黄土20%处理下玉米根长密度最大,分别为掺黄土0%、10%和40%的3.2、2.4、2.8倍,水分胁迫后根系具有向下生长、吸取深层水分的能力;基于δ^(18)O值的MixSIAR模型水源分析,掺黄土0%处理下玉米主要利用0~25 cm处的水分,水分利用效率达到80%;掺黄土10%处理下玉米主要利用15~35 cm处的水分,水分利用效率达到64%;而掺黄土20%处理下玉米对0~25 cm处的水分利用效率仅为36%,对25~45 cm处水分利用率达到64%,说明掺黄土20%处理下玉米主要利用土壤深层水分。接种DSE提高了植物吸收更深层水的能力,掺黄土20%处理下水分利用深度向下增加了5 cm,掺黄土20%基质中接菌处理在干旱胁迫后植物根系提水量达到最大,生长期总提水量较不接菌处理提升了45%;在不接菌条件下掺黄土20%植物根系提水量是掺黄土0%的1.45倍,而在接菌条件下掺黄土20%植物根系提水量可达到掺黄土0%的1.72倍。综上认为,接种DSE及土层重构均对提升植物提水能力具有显著作用。此外,本研究结果对露天矿区排土场土层重构过程中土壤改良及植物的水分利用效率提供实验参考依据。

Soil layer reconstruction of open-pit coal mine dump is of great significance for ecological reconstruction.In order to study the effect of inoculation of dark septate endophytes(DSE)on water utilization of corn root system under different reconstructed soil layer models,soil column simulating and culturing test was adopted,with DSE inoculation and control treatment set up under each of the four soil layer types,in a total of 8 groups.The results show that the roots of corn are the longest with the maximum density under the treatment with 20%loess,which are 3.2,2.4 and 2.8 times that of 0%,10%and 40%loess respectively.After water stress,the root system has the capability to grow downward and absorb deep water.According to the water source analysis of MixSIAR model based onδ^(18)O value,the water at the depth of 0-25 cm is mainly used by corn at the water utilization ratio of 80%under the treatment with 0%loess,and the water at the depth of 15-35 cm is mainly used by corn at the water utilization ratio of 64%under the treatment with 10%loess.However,the water utilization ratio of corn is 36%at the depth of 0-25 cm only and 64%at the depth of 25-45 cm under the treatment with 20%loess,indicating that the water in deep soil is mainly used by corn under the treatment with 20%loess.The DSE inoculation improves the capability of plants to absorb deeper water.Specifically,the depth of wa-ter used increases by 5 cm under the treatment with 20%loess.The hydraulic lift of plant roots is maximized under drought stress through inoculation treatment in the matrix containing 20%loess,with the total hydraulic lift during the growth period increased by 45%compared with that treatment without DSE inoculation.The hydraulic lift of plant roots mixed with 20%loess is 1.45 times that of 0%loess under the condition without DSE inoculation,while the hydraulic lift of plant roots mixed with 20%loess can reach 1.72 times that of 0%loess under the condition with DSE inoculation.In conclusion,DSE inoculation and soil layer reconstruction have significant effects on improving the hydraulic lift of plants.In addition,the results of this study could provide experimental reference basis for the improvement of soil and water utilization efficiency of plants in the process of soil layer reconstruction of open-pit mine dump.