| The Yellow River Delta, located in the Yellow River estuary, is close to theBohai Sea. Because of its unique geographical location, the ecological restoration ofthe Yellow River Delta has always been the hot spot of the scholars study. We studiedthe soil microbial ecological system of the test field, which belonged to the teamresearching the energy crops cultivation of saline-alkali land in the Yellow Riverdelta,with both the traditional plate culture method and modern molecularbiotechnology.We researched the effect of different energy plant and agronomicpractices on the soil-microorganisms, physicochemical property, enzyme activity ofthe saline-alkali land; extracted, purified, amplified the genome DNA selectivety andanalyzed the rhizosphere microoranism using RFLP and RAPD. We hoped that theresults could provide some theoretical basis for the ecological restoration of theYellow River Delta, the improvement of saline-alkali land quality, the scale-expansionof cultivation and production of the energy plant. The main research contents andresults were as follows:1. Bacteria accounted for absolute advantage in the rhizosphere microbes inplants, whose quantity had a strong linear relationship with the total number of thecultivatable rhizosphere microoganisms(r>0.95). After the cultivation of energy plants,the structure of the soil microbial community was changed, the content of salttolerance microorganism was lower. Different changes appared in the different energyplants′rhizosphere soil microbes, and the number of the microorganisms in sweetsweet potato rhizosphere increased more than that in other pieces of test field.2. Rhizosphere environment of energy plant responded to different farmingmethods differently. Film mulching increased both the rhizosphere microbial quantity,improved the soil relative water contents and reduced the soil salinity. Higher plantingdensity would cause the individual competition for space and nutrients, and the lowerwould affect the effective area of plant photosynthesis. So reasonable plant density were significant to plant growth. To combine with other method could reduce thenegative impact of unreasonable planting density (such as the data that density testfield of pennisetum showed). The results of the organic fertilizer test showed that amixture of organic fertilizer and compound fertilizer was more conducive to theimprovement of soil quality than applying single fertilizer. Applying organic fertilizercould increase the number of soil microorganisms, but the application amount did notaffect the soil microorganisms’ quantity obviously. Foliar topdressing could increaserhizosphere microbial quantity more significant than furrow application. Because ofthe grouding-leaves of sweet potato, foliar topdressing might lead to the enrichmentof the salt-tolerate microorganisms. This phenomenon did not appear in test site ofsorghum or the pennisetum3. Agronomic practices could change the physicochemical property of therhizosphere soil. Fertilization is essential to the improvement of soil quality. Thefertilizer itself, the fertilization methods and the application amount all had a directimpact on the physicochemical property of soil. Energy plants,especially the sweetpotato, could improve soil sucrase and urease activity. The application amount of theorganic fertilizer influenced the soil enzyme activity, but the pennisetum rhizosphereenvironment was not sensitive to the factor. The method and the fertilizer oftopdressing both could affect the enzyme activity of the rhizosphere soil enzymaticactivity. Topdressing had a more significant effect on sucrase activity than that of theurease.4. According to RFLP profiles, fungi showed a higher level at RFLP than that ofbacteria. Through the analysis of RAPD results, we found out that the cultivation ofthe energy plants did have an impact on the diversity, richness and uniformity of thesoil microbial genome DNA. And topdressing had a more significant effect on thethree index than that of the organic-fertilization treatment. |
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