| Sweet sorghum is a high-sugar,high-energy C4 plant.It has the advantages of drought tolerance,waterlogging tolerance,barren tolerance,lodging resistance,and salinity tolerance.It is an advantageous crop for the production of edible alcohol.In Gansu Province,the weather conditions are poor,water resources are scarce,and the marginal soil area such as sandy wasteland,saline-alkali land and hillside land reaches 667,000 hectares.Therefore,planting sweet sorghum in Gansu not only meets the requirements of developing water-saving and efficient agriculture,but also effectively uses marginal land.However,due to the complex structure of sweet sorghum and the structural contradiction between seasonal harvest and sustainable supply of raw materials,it is inevitably required that sweet sorghum can sustainably and stably supply and destroy its complex structure to achieve high production of edible alcohol.In this study,sweet sorghum was used as raw material to analyze the effects of additives（cellulase,xylanase,rumen fluid and biogas fluid）on organic components,fermentation quality,microstructure,microbial diversity and biodegradability of sweet sorghum silage.The main conclusions are as follows:（1）Comprehensive analysis of organic components,fermentation quality and microstructure in each group showed that with the prolongation of storage time,the contents of dry matter（DM）,neutral detergent fiber（NDF）,acid detergent lignin（ADL）,hemicellulose（HC）,ammonia nitrogen（AN）,crude protein（CP）,pH（except RT and BT groups）and cellulase activity decreased,but cellulose（CEL）,acetic acid（AA）,propionic acid（PPA）contents,xylanase activity and manganese peroxidase activity increased.On the whole,DM loss rate in CK group was lower than that of additive treatment groups,while the content of NDF,ADL,HC and CP（except CT group）were higher than that of additive treatment group.The content of LA in CT and XT group was higher than that of other groups,pH value,AN,AA,PPA and ethanol（EOL）content were lower than that of other groups,and cellulase activity and xylanase activity were higher in CT and XT groups,respectively.The content of WSC,AN,AA,PPA and EOL were higher than other groups,and the content of lignocellulosic component in BT group was the lowest,the activity of cellulase was the highest.In addition,after silage,the surface pores and cracks increased,the functional groups between cellulose and lignin were destroyed,and the crystallinity of cellulose decreased.In the additive group,the surface pores and cracks of sweet sorghum were more than those of CK group,and the crystallinity of cellulose was significantly lower than that of CK group.Compared with CK,RT and BT groups showed the most significant difference.（2）Comprehensive analysis of microbial diversity showed that there were considerable lignocellulosic bacteria and fungi in rumen fluid and biogas slurry.After silage,the diversity and richness of bacteria and fungi decreased.The dominant bacteria at the level of each phylum were Firmicutes,and the dominant bacteria at the level of genus were Lactobacillus,Pantoea,Rummelibacilli and Clostridium.With the extension of time,the relative abundance of Lactobacillus in each group increased（except CK group）.After ensiling 90 days,the relative abundance of Lactobacillus in CT and XT groups were significantly higher than that of other groups and the relative abundance of Clostridium in RT and BT groups were higher than that of other groups.Ascomycota and Basidiomycota were the dominant fungi at the level of each phylum,and Wickerhamomyces was the dominant fungi.The relative abundance of Wickerhamomyces in additive treatment groups were higher than that in CK group.（3）Comprehensive analysis of the biodegradability of sweet sorghum silage showed that with the extension of storage time,the yield of reducing sugar in CK and BT groups increased after enzymatic hydrolysis for 72 h,while that in CT,XT and RT groups decreased.In addition,after storage for 45 days,the order of reducing sugar yield in each group was RT（780.78 mg/g）>BT（778.63 mg/g）>XT（729.78 mg/g）>CT（702.49 mg/g）>CT（603.36mg/g）,which was higher than that of the raw material（588.20 mg/g）.After storage for 90days,the order of reducing sugar yield in each group was BT（846.87 mg/g）>RT（749.90mg/g）>CT（688.62 mg/g）>XT（663.25 mg/g）>CK（646.30 mg/g）.With the increase of storage time,the concentration of cellobiose decreased and the concentration of glucose increased（except CK group）.After 45 days storage,the cellobiose concentration of XT and RT groups were higher than that of other groups,and the glucose concentration of RT and BT groups were higher than that of other groups.After 90 days storage,the cellobiose concentration in BT and CT groups were higher than that of other groups,and the glucose concentration in RT and BT groups were higher than that of other groups.In summary,adding cellulase and xylanase to sweet sorghum silage could promote lactic acid fermentation,reduced pH value,AN content and microbial diversity,Inhibited the undesirable microorganisms and ensured silage quality.The addition of rumen fluid and biogas slurry could destroy the complex structure of lignocellulose and increased the yield of enzymatic hydrolysis sugar by 192.58 mg/g（45 d）,161.70 mg/g（90 d）and 190.43 mg/g（45 d）and 258.67 mg/g（90 d）,respectively compared with the raw material.The yield of enzymatic hydrolysis sugar increased 177.42 mg/g（45 d）,103.60 mg/g（90 d）and 175.27 mg/g（45 d）and 200.57 mg/g（90 d）,respectively compared with the control group which is showed that rumen liquid and biogas slurry could improve the biodegradability of sweet sorghum. |
