摘要：

为研究高粱、玉米残体腐解特征及腐解进程中秸秆腐解微生物群落功能多样性的变化,设置残体类型(高粱茎叶、玉米茎叶、高粱根系、玉米根系)、土壤类型(潮褐土、黄壤土)、氮处理(调节碳氮比、不调节)3个变量,通过2次试验分析不同腐解条件下残体的腐解特征(干物质降解率、碳矿化特征、纤维素、半纤维素和木质素的降解率),并使用BIOLOG-ECO板分析秸秆腐解微生物群落代谢多样性。结果表明,高粱、玉米残体腐解速率均表现出前期快后期慢的特征,表明在相同土壤和氮处理条件下,残体干物质降解率及碳矿化速率表现为高粱茎叶>玉米茎叶>高粱根系>玉米根系;由第2次试验可知,潮褐土条件下腐解60 d,高粱茎叶+N处理、玉米茎叶+N处理的干物质降解率分别为55.50%,48.00%,而高粱根系+N处理和玉米根系+N处理的干物质降解率分别为31.25%,16.75%。在相同土壤和氮处理条件下,同一作物根系的半纤维素、纤维素的降解率低于茎叶,腐解90 d,潮褐土条件下高粱根系+N处理对半纤维素、纤维素降解率分别比高粱茎叶+N处理降低了23.70,18.80百分点。对秸秆腐解微生物代谢多样性的分析表明,腐解30 d秸秆腐解微生物代谢活性最高,腐解90 d微生物代谢活性最低;与30 d相比,在腐解第1天,秸秆腐解微生物群落对胺类、酚酸类代谢能力较低,第90天秸秆腐解微生物群落对碳水化合物、氨基酸类、多聚物类代谢能力均明显降低。由此可见,在该试验条件下,高粱残体比玉米残体更易腐解,调节碳氮比可在一定程度上加速残体腐解,秸秆腐解30 d微生物代谢多样性最高。

关键词: 高粱, 玉米, 残体腐解, 碳矿化, 纤维素, 半纤维素, BIOLOG-ECO

Abstract:

To study the decomposition characteristics of sorghum and maize residues and the functional diversity of microbial community in straw decomposition,under different residual types(sorghum stalk-leaves,maize stalk-leaves,sorghum root,maize root),soil type(cinnamon soil,yellow loam soil),nitrogen treatment(adjust C/N ratio,not adjusted),the culture experiment method was used to explore the decomposition characteristics of residues under different decomposition conditions,and to analyse the metabolic functional diversity of microbial community used the BIOLOG-ECO plates method in straw decomposition process.The results showed that the decomposition rate of sorghum and maize residues was faster in the early stage than the late stage.The residual dry matter degradation rate and CO₂ release rate had the following pattern of decomposition rate was shown,sorghum stalk-leaves>maize stalk-leaves>sorghum root>maize root,under the same soil and nitrogen treatment.According to the second experiment, the dry matter degradation rates of sorghum stalk-leaves and maize stalk-leaves were 55.50% and 48.00%,respectively,however,the dry matter degradation rate of sorghum root and maize root were 31.25% and 16.75%,respectively at 60 d of incubation,under the condition of cinnamon soil+N treatment.The degradation rate of hemicellulose and cellulose in root were lower than that in stalk-leaves,under the same soil and N treatment conditions,the decomposition of hemicelluloses and cellulose was decreased by 23.70,18.80 percentage point,in sorghum root treatment than sorghum stalk-leaves treatment at 90 d of incubation,under the condition of cinnamon soil+N treatment.The microbial metabolic activity of straw was the highest at 30 d and lowest at 90 d during decomposition.The metabolizable ability of microbial community of straw decomposition to amines and phenolic acids was lower on the 1st day of decomposition,and the metabolizable ability to carbohydrates,amino acids and polymers was significantly decreased on the 90th day,compared with 30 d.Collectively,the decomposition of sorghum residues was easier than maize,and adjusting C/N ratio could accelerate the decomposition of residue to a certain extent.The microbial metabolic diversity was the highest at 30 d under the experimental conditions.

Key words: Sorghum, Maize, Residues decomposition, Carbon mineralization, Cellulose, Hemicelluloses, BIOLOG-ECO