| Crop straw is a kind of renewable resource in nature.At present,a large part of crop straw is discarded and piled randomly in farmland,and a small part is burned by farmers.The annual output of straw in China is 900 million tons.The traditional treatment of straw affects the soil,resulting in environmental and agricultural resource waste.Cellulose,hemicellulose and lignin are the main components of crop straw.Microorganism biodegrades the components of crop straw,so as to accelerate the effective degradation of crop straw.Therefore,it is of great significance for improving the utilization rate of agricultural resources how to construct efficient degradation bacterial community of crop straw.This test the crops straw returned on the saline soil in tianjin region,especially in the corn straw returned,mainly studied the degradation of separation,screening of strain,the high efficient degradation compound bacterium group building,optimization of culture conditions of high efficiency degradation compound bacteria,efficient degradation compound bacteria on the three main crops of corn,rice and wheat straw degradation effect,etc.The main results are as follows:1.Screened out straw-degrading strains in several soils and cultured them in Congo red medium.12 straw-degrading strains were obtained through primary screening and re-screening.By comparing the size of the transparent hydrolytic circle around the strain,the ratio of the diameter of the hydrolytic circle to the diameter of the colony was that the D/d value of K-7 was 4.333,and a strain with strong degradation ability was obtained.K-7 was identified as Aspergillus Niger by morphology.2.After the above screening,the strains with high enzyme production activity and the strains purchased by combination were cultured in pairs with the compound bacterial group,and the CMCase enzyme activity,filter paper enzyme activity,Xylanase enzyme activity and Laccase activity of each compound bacterial group were measured.The compound bacteria DF which can degrade cellulose efficiently was selected.Compared with single strain,the CMCase activity of DF was38.40U/m L.Amylase activity（FPA）was 38.40U/m L.Xylanase activity（36.14U/m L）;DF also had the highest Laccase activity（34.24U/m L）.3.In order to give full play to the role of the high-efficient degradation complex flora constructed in this experiment in farmland,the conditions affecting the enzyme production activity of the complex flora were optimized,such as the influence of culture temperature and p H value of culture medium on the degradation complex flora of corn,wheat and rice straw.Through experiments,the conditions of the complex bacterial community constructed in this study were as follows: the highest enzyme activity appeared in the 4d of culture,the most suitable culture temperature was 15℃,and the most suitable culture medium p H value was 9.0.4.In order to understand the degradation effect of the compound bacterial community constructed in this experiment on crop straw in practical application,pot experiment was used to simulate the field experiment.The constructed complex flora was added to soil and straw,and wheat was planted in pot.The results showed that the constructed high-efficient degradation complex flora had a good degradation effect on corn straw through wheat growth,chlorophyll content and straw degradation rate.The final total degradation rates were 11.5%,1.2%,7.85% and 56.05% higher than those of K-7,DE,COMMERCIAL agent and CK,respectivel The constructed complex flora was added to soil and straw,and wheat was planted in pot.According to wheat growth,chlorophyll content and straw degradation rate,the total potassium content of DF was2.25%,which was 15.98% higher than CK and 2.03% higher than k-7.The alkali-hydrolyzed nitrogen content was 0.098g/kg,24.05% higher than CK,2.74%higher than single strain K-7.The content of available phosphorus was 145.3mg/kg,which was 6.60% higher than CK and 9.26% higher than k-7.The content of available potassium was 431.01mg/kg,29.86% higher than CK,14.66% higher than k-7.The organic matter content increased by 8.81% compared with that of single strain K-7.Compared with blank control,the p H and conductivity of straw degrading bacteria treatment did not decrease,and there was no significant difference.The results showed that the high efficient degradation complex bacteria had a good degradation effect on corn straw.The final total degradation rates were 11.5%,1.2%,7.85% and 56.05%higher than those of K-7,DE,COMMERCIAL agent and CK,respectively.y. |
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