Effects Of Salinity And PH On Soil Microbial Diversity In Coastal Saline Soil

Coastal saline soil is an important pattern of land resources, widely distributed in122countries andregions of5continents with the area being over10×108hm2. Excess salt in soil will change soilphysical and chemical properties, resulting in the degradation of most crop growth environment. Soilmicroorganisms are more sensitive to the changing of soil physical and chemical conditions and quicklyreacting to the changing of soil microenvironment so as to indicate the changes of soil ecosystemfunctions earlier to provide a reliable basis for forecasting the development of coastal saline soil.The experiments were conducted in this study through setting different salt and pH gradients toresearch effects of salt and pH on soil microbial diversity by using PCR-DGGE and PLFA. The studyconclusions are as following:1）The bacteria diversity index is lower with higher pH of soil.49days after microbe culture test, soilbacteria diversity index increased slightly in CK (pH8.3) rising to3.14. Diversity index of P1(pH9.0)had fallen to2.96, while diversity index of P2(pH10) had reached to2.85. So, the effect on soilbacteria is more significant with the higher pH of soil. Alkaliphilics like Pontibacter sp. Bacillushorikoshii and Bacillus lehensis can be better growth in environment of strong alkaline.2) The fungal diversity index is lower with higher pH of soil. here were little effects on fungalcommunity structure in soil when the value of pH is9. Diversity index of pH10was much lower thanthat of CK with the level of2.92, Alkaliphilics like Pycnidiophora sp., Sordariales sp. and Aspergillusversicolor disappeared, while Emericellopsis terricola, Fusarium solani and Verticillium dahliae strainF724arose.3) There were little effects on bacteria community structure in soil when the soil salinity increasefrom1.91-26.99g NaCl kg-1. Some alkaliphilics dissapear when the soil salinity is26.93g/kg. At thesame time, Alkaliphilics like salty environment appear, such as Pontibacter sp. MDT2-9occupied thedominant position when the soil salinity is9.41g/kg and19.759.41g/kg. While,with the soil salinityincrease to26.93g/kg, it’s dominant position being insteaded.4) When soil salinity increased, soil fungal diversity index arose. When cultured for49d, theascomycete sp. had the advantage in CK, but reduced in S1（soil salinity9.41g/kg）, S2（soil salinity19.75g/kg）and S3（soil salinity26.93g/kg）. In other words, the soil NaCl inhibited the growth andreproduction of the fungus. Aspergillus sp. in CK did not exist, but exist in S1（soil salinity9.41g/kg）,S2（soil salinity19.75g/kg）and S3（soil salinity26.93g/kg）, the increase in soil salinity wasconducive to the growth of the genus.5）The increse of soil pH and the salt content significantly reduced the total PLFAs bacteria’s PLFAsand the Gram-positive bacterium’s PLFAs in the soil. While there were little effects on fungal andGram-negetive bacterium’s PLFAs. As the increasing of pH and the salt content, the kinds of PLFAsreduced.