Effects Of Saline Alkali Soil Improvement Methods On Microbial Diversity And Screening Of Functional Strains

Firstly,the concept,formation and improvement of saline alkali soil and the general situation of soil in Jiuquan area of Gansu province were introduced briefly.Then,the research progress of microbial diversity and microbial functional groups in saline alkali soil was introduced.After that,the effects of straw returning and tillage methods on soil and the screening of salt tolerant,salt stress relief and growth promotion strains were introduced.The types and numbers of microorganisms in soil as an important index to appraise soil fertility,through analysis of soil microbial community structure can provide important reference for reasonable utilization of cultivated land,improving agricultural tillage and returning methods to saline areas with similar soil conditions.In this paper,saline alkali soil from Jiuquan was treated in different ways,including different returning methods of straw and matching tillage methods,and then the change of soil microbial number and species was determined.The results showed that the mode selection of straw returning to soil was different in increasing soil microbial species and number in the different depth of soil: selection of plant ash to cover the soil surface;selection of biological carbon or corn straw crushing in the 15 cm soil layer;selection of corn straw compressed granules,plant ash or whole corn stalk in the 25 cm soil layer;the first selection of plant ash,and the second selection of biological carbon or corn straw crushing in the 40 cm soil layer.The effects of the same straw shape in different depths on soil microorganisms and the effects of the same straw shape with multiple quantity on soil microorganisms were also investigated.The matching tillage method of straw returning to field to promote microbial growth may consider the use of 50 perforated film,organic manure,straw mats on the soil surface;considering the use of straw compressed granules + agent and reed + agent in the 25 cm soil layer;considering the use of reed + agent in the 40 cm soil layer.In addition,the growth promoting functions of YP,BZ1 T and LE,the salt stress relief and growth promotion strains we screen,were studied.Research shows that strain YP has obvious effect on dissolved inorganic phosphorus and organic phosphorus,soluble inorganic phosphorus content up to 516.8mg/L,the highest content of soluble organic phosphorus reached 292.2mg/L;strains LE,BZ1 T and YP have the ability to secrete IAA,the concentration of IAA secreted by strain LE reached 20.92?g/m L in 7 days;the concentration of IAA secreted by strain BZ1 T reached 14.80?g/m L in 7 days;the concentration of IAA secreted by strain YP reached 9.79?g/m L.Strains YP,BZ1 T and LE are not suitable for promote seed germination,but strain YP have a good role on promoting plant growth,consider adding YP agent after the sunflower grows out of the seedlings to achieve the purpose of promoting the growth of crops.The sequence of 16 S r RNA gene of strain YP,comparing with Gen Bank database showed that the similarity between YP and Ensifer meliloti LMG 6133(T)was the highest,99.93%.