Effects of Sand Fixation Using Microbially Induced Carbonate Precipitation on Leaf Traits and Physiological Characteristics of Typical Psammophytes
Microorganism induced carbonate precipitation(MICP)can fill soil pores,reduce water evaporation and enhance the wind erosion resistance of aeolian sandy soil.Its effect of wind prevention and sand fixation has been confirmed,but its impact on the leaf characteristics and growth physiological process of sandy plants is not clear.In order to reveal the effect of micro-organism-induced calcium carbonate precipitation and sand fixation on the leaf characteristics and photosynthetic physiological characteristics of desert plants,the indoor pot experiment was carried out with 4 kinds of desert plants,namely,Agriophyllum squarostrum,Astragalus laxmannii,Caragana korshinskii and Corethrodendron fruticosum as the research objects.The leaf characteristics and physiological characteristics of desert plants with high(H),middle(M)and low(L)microbial agent levels and top(T),centre(C)and bottom(B)of consolidation layer were compared and analyzed.The results were followed.① Microorganism induced carbonate was distributed among the aeolian sand particles,and it was cubic,rhombic,spherical and amorphous,which could cement the aeolian sand particles.② The microbial agent treatment significantly increased the soil organic matter and calcium carbonate contents of 4 types of sandy plants.When high level of microbial agents were applied,the soil organic matter and calcium carbonate contents of consolidation B layer treatment group were significantly higher than those of the other treatment groups.The organic matter content in the soil of A.laxmannii increased the most,reaching to 90.19%,while the calcium carbonate content in the soil of C.korshinskii increased the most,reaching to 41.47%.③ The specific leaf area of A.squarostrum in high level microbial agent treatment group was significantly higher than those in other treatment groups,average increase of 0.98%;and the dry matter contents of A.squarostrum and A.laxmannii in low level microbial agent treatment group were significantly higher than those in other treatment groups,with an average increase of 34.11%and 24.18%,respectively.In the consolidation layer C treatment group,the specific leaf areas of A.squarostrum,A.laxmannii and C.korshinskii were significantly lower than those in the other treatment groups.④ The content of chlorophyll in leaves of A.squarostrum,A.laxmannii and C.korshinskii under the high level microbial agent treatment group were significantly higher than those in the other treatment groups,with an average increase of 9.01%,12.97%,and 31.77%,respectively;and the maximum net photosynthetic rates of the middle level microbial agent treatment group were significantly higher than those in the other treatment groups,with an average increase of 55.70%,48.39%and 13.24%,respectively.In conclusion,the application of microbial agent could increase the contents of soil organic matter and calcium carbonate,provided sufficient nutrients for plant growth.Therefore,the photosynthetic physiological characteristics of A.membranaceus,A.obliquus,and C.caragana under the microbial agent treatment groups were significantly higher than those of control.However,the response of plant leaf traits to soil organic matter and calcium carbonate content was not significant.MICP could promote the leaf traits and photosynthetic physiological characteristics of A.squarostrum under the middle level microbial agent treatment and the high level treatment of A.laxmannii and C.korshinskii,but could inhibit the leaf traits and physiological characteristics of C.fruticosum.Above results provided theoretical basis and scientific support for enriching and improving the technology of microbial induced calcium carbonate precipitation and sand fixation.
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