| The continuous growth of rice yield leads to the production of a large number of straws,and the excess straw is too late to deal with or improperly handled,which will cause serious waste of resources and even environmental pollution.Researchers at home and abroad use physical,chemical and biological methods to deal with straw,and find that a single method has defects,such as energy consumption,secondary pollution and so on.Therefore,it is urgent to find an economical and effective way of straw utilization.In this study,nematodes were used to treat rice straw with white rot fungi and ecomposing microbial inoculums,and non-pathogenic saprophytic nematodes(identified as Cephalobidae,Cervidellus)and rice straw were used for aerobic fermentation,the carbon-nitrogen ratio of fermentation materials was kept about 30,3%decomposing microbial inoculums was added,and the moisture content was controlled at about 70%.Four groups of trials were set up:group A(rice straw with decomposing microbial inoculums),group B(rice straw with decomposing microbial inoculums and white rot fungi),group C(rice straw with decomposing microbial inoculums and nematodes fed on Botrytis cinerea),group D(rice straw with decomposing microbial inoculums and nematodes fed on white rot fungi),which was sampled regularly.The Behrman funnel method was used to determine the number of the nematode.The content of lignocellulose was measured by high performance liquid chromatography(HPLC).The content of total nitrogen was measured by Kjeldahl nitrogen meter.The content of total carbon was measured by total organic carbon analyzer(TOC).The results were as follows:(1)It was found that the conditions for the largest number of nematodes were as follows:the altitude was 20?30 m,the vegetation type was shrub,and the sampling site was Yizi Mountain.Through the orthogonal trial design of mixed level,there were 7 levels in altitude,6 levels in vegetation and 2 levels in sampling sites.84 experiments were obtained by range analysis,and nematode abundance was used as an index,the key factors affected the number of nematodes were obtained by range analysis.According to the analysis of the range,the key factors affected the number of nematodes from large to small were vegetation type,altitude and sampling location.(2)It was found that nematodes could multiply in large numbers when rice straw was fermented for 7 days and then put into nematodes;And the increase in the number of nematodes fed on Botrytis cinerea was greater than that on white rot fungi.Nematodes were added to the materials at the starting point of fermentation and after 7 days of fermentation,after 9 days of culture,it was found that the number of nematodes in 100 g dry materials increased from 18212 to 30382 and 35139 to 379316,respectively.This showed that the materials fermented for 7 days were more conducive to the increase of nematodes than the materials at the starting point of fermentation.The nematodes fed on white rot fungi and Botrytis cinerea were inoculated into rice straw for fermentation,the results showed that the number of nematodes increased from 55442/100 g dry fermentation to 116484/100 g dry fermentation and 12835/100 g dry fermentation to 910384/100 g dry fermentation,which indicated that the nematodes fed on Botrytis cinerea were more suitable for growth on rice straw.(3)It was found that the cellulose content of fermentation products decreased the most in the group with white rot fungi,and the hemicellulose content in the nematodes fed on white rot fungi decreased the most.The cellulose content in the group with white rot fungi and decomposing microbial inoculums decreased from 33.19%to 24.79%,followed by the group in which rice straw was added with decomposing microbial inoculums and nematode fed on white rot fungi,which decreased from 33.54%to 25.99%.Compared with the group without nematodes,the group with nematodes had a better effect on the decomposition of cellulose.Hemicellulose content in group A,B,C and D decreased from 18.84%,18.43%,18.73%,and 19.57%to 17.01%,15.48%,17.24%and 16.17%,respectively.(4)It was found that the protein content of fermentation products increased more with the addition of white rot fungi;And the more the number of nematodes,the higher the protein content of fermentation products.The protein content of fermentation in groups A,B,C and D increased from 6.85%,7.33%,6.83%and 6.99%to 8.35%,9.29%,8.68%and 8.54%,respectively.Compared with the group without nematodes,the protein content of fermentation products after adding nematodes in rice straw was higher.(5)It was found that the aerobic fermentation of rice straw and leftover could inhibit nematodes.The addition of white rot fungi was beneficial to increase the protein content of fermentation products.And the nematodes fed on white rot fungi promoted the degradation of cellulose.Nematodes fed on Botrytis cinerea promoted the decomposition of hemicellulose.Rice straw and leftover were used for fermentation,330000,220000 and 400000 nematodes were added to survive under stress on the 0,4 and 9 days,respectively,and the number of nematodes isolated decreased each time.At the end of sampling,44 nematodes per 100 g dry fermentation and 20 nematodes per 100 g dry fermentation were isolated in group C and D,respectively.In the aerobic fermentation of leftover and rice straw,the protein content of fermentation products increased by 2.22%in the group fed on white rot fungi,and the cellulose degradation effect was better in the group fed on white rot fungi,and the cellulose content decreased by 8.13%.The hemicellulose decomposition effect of the nematode group fed on Botrytis cinerea was better,and the hemicellulose content decreased by 4.39%.To sum up,the combined fermentation of rice straw by nematodes and white rot fungi could not only promoted the decomposition of rice straw,but also increased the protein content of fermentation products,which was beneficial to realize the utilization of biomass and expand the utilization channels of rice straw,and has a broad market prospect. |
PDF Full Text Request