水稻秸秆降解复合菌系的筛选构建及其田间应用效果

李阳阳; 陈帅民; 范作伟; 徐铭鸿; 王学文; 张立明; 刘慧涛; 吴海燕

doi:10.11674/zwyf.2021154

水稻秸秆降解复合菌系的筛选构建及其田间应用效果

Construction and screening of complex microbial system for efficient degradation of rice straw and their application effects under field condition

摘要

摘要:
目的筛选并构建适宜原位还田水稻秸秆快速腐解的高效多功能复合菌系，以提高秸秆原位还田的腐解速率。
方法秸秆原位腐解菌株从水稻田带有腐烂秸秆的表层土壤中筛选分离，分别采用DNS法、摇瓶培养观察法和失重法测定了腐解菌株的羧甲基纤维素酶活性、滤纸崩解能力及水稻秸秆降解能力，对降解效果较好的菌株进行了16S rRNA或18S rRNA鉴定。选取无拮抗作用的菌株构建复合菌系，并在实验室条件下测定各复合菌系的滤纸酶活性和秸秆降解率。挑选降解效果较好的复合菌系进行田间试验，分析了秸秆降解率、土壤有机质及速效养分含量，调查了水稻产量。
结果从土壤中共分离到秸秆降解率均高于19.8%的菌株有6个，包括B2、B5、B6、F1、F5、F12，经鉴定分别为贝莱斯芽孢杆菌(Bacillus velezensis，B2)、耐盐芽孢杆菌(Bacillus halotolerans，B5)、枯草芽孢杆菌(Bacillus subtilis，B6)、米曲霉(Aspergillus oryzae，F1)、黑曲霉(Aspergillus niger，F5)、长枝木霉(Trichoderma longibrachiatum，F12)，其中F12 (长枝木霉)的秸秆降解率最高(29.1%)。以该6个菌株构建了7组复合菌系，复合菌系B2+F12、F1+F5+F12、B2+F5+F12的秸秆降解效果较好，在液体培养基中，对秸秆的降解率分别达到32.9%、29.8%、40.3%。利用这3组复合菌系进行田间试验，结果表明，复合菌系B2+F5+F12表现最好，与未施菌剂相比，原位还田的水稻秸秆降解率提高了37.1个百分点，土壤有机质、碱解氮、速效磷、速效钾含量分别增加了2.1 g/kg、1.9 mg/kg、0.6 mg/kg、1.7 mg/kg，水稻产量提高了6.3% (P<0.05)。
结论施用复合菌系B2+F5+F12不仅具有良好的水稻秸秆降解能力，同时能增加土壤有机质、碱解氮、速效磷、速效钾含量，并促进作物产量的提高，具有较好的应用潜力。

Abstract:
Objectives To overcome the adverse effect of slow in situ degradation of rice straw, high-efficiency multifunctional complex microbial agents suitable for rapid in situ decomposition of rice straw were screened and constructed.
Methods Straw decomposition strains were screened and isolated from the surface soil with rotten straw in a rice field. The carboxymethyl cellulase activity, filter paper disintegration, and rice straw degradation ability of these strains were determined by DNS, shake flask culture observation, and weight-loss method. The strains with high degradation effects were identified by 16S rRNA or 18S rRNA. Complex microbial agents were constructed by selecting the strains without antagonistic effect. We used filter paper to measure enzyme activity, and used rice straw to measure the degradation rate under laboratory conditions. We selected the agents with higher degradation effects for field experiments. The straw degradation rate, soil organic matter, available nutrients, and rice yield were investigated.
Results Strains B2, B5, B6, F1, F5, and F12 were identified as Bacillus velezensis, Bacillus halotolerans, Bacillus subtilis, Aspergillus oryzae, Aspergillus niger, Trichoderma longibrachiatum, respectively. The degradation rates of these strains were all higher than 19.8%. The degradation rate of F12 was the highest (29.1%). Seven complex microbial agents were constructed with the six strains identified. Complex microbial agents B2+F12, F1+F5+F12 and B2+F5+F12 showed good degradation effects in the straw liquid medium, and the degradation rates were 32.9%, 29.8%, and 40.3%, respectively. B2+F5+F12 showed the highest potential for application in field. Compared with no agent, the in situ degradation rate of rice straw increased by 37.1 percentage point. Soil organic matter, alkali hydrolyzable N, available P, and readily available K increased by 2.1 g/kg, 1.9 mg/kg, 0.6 mg/kg, and 1.7 mg/kg, respectively. Similarly, rice yield (P<0.05) increased by 6.3%.
Conclusions Complex microbial system B2+F5+F12 had good rice straw degradation ability. It increased the contents of soil organic matter, alkali hydrolyzable N, available P and K, which promoted crop yield improvement. Therefore, we conclude that complex microbial agent B2+F5+F12 has good application potential.

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