稻田土壤β-1,4-葡萄糖苷酶活性对温度变化的响应特征

Responses of β-1,4-Glucosidase Activity to Temperature Changes in Paddy Soil

温度是土壤酶活性的关键非生物影响因子,调控着土壤物质周转过程.为了探究温度变化对稻田土壤有机质周转及其关键胞外酶活性的影响,设计室内培养试验,分别在5、15、25和35℃下测定亚热带稻田土壤BG(β-1,4-葡萄糖苷酶)活性,探究温度对土壤胞外酶活性及其与碳氮转化过程的影响特征.结果表明:稻田土壤中w(DOC)(DOC为可利用态碳)、w(NH4+-N)和w(MBC)(MBC为微生物生物量碳)在5~25℃下随着培养时间的增加而降低.在第15天时BG活性达到306.57~437.75 nmol/(g·h),并随温度的增加表现为先增后减,在第3、75天时,25℃下BG活性为184.46~207.60 nmol/(g·h).土壤酶活性的Q10(温度敏感性)在15℃升至25℃时表现出正响应(Q10=1.5),而在5~15℃和25~35℃时Q10<1,表现为消除效应.土壤酶活性的变化是多因素共同影响的结果,温度作为关键影响因子,升温显著改变了土壤中w(DOC)、w(NH4+-N)、w(MBC)、w(MBN)(MBN为微生物生物量氮),进而影响土壤BG活性;土壤中w(MBC)对BG活性具有直接的显著负影响作用.研究显示,对参与稻田土壤碳转化BG酶活性的温度敏感性及其与土壤关键理化因子之间的耦合关系进行量化,有助于深入开展水稻土碳循环及其调控机制研究.

bAs a key biotic factor,temperature affects the soil enzyme activity and regulates soil carbon（ C） and nitrogen（ N） cycling. In order to clarify the response of temperature changes to the β-1,4-glucosidase（ BG） enzyme,which mainly involves in soil C and N turnover,an incubation experiment was conducted at 5,15,25 and 35 ℃,respectively. The results showed that soil dissolved organic carbon（ DOC）,ammonium nitrogen（ NH4＋-N） and soil microbial biomasses were decreased over time at 5 and 25 ℃. The maximal enzyme activity potential of glucosidase was ranged in 306. 57-437. 75 nmol/（ g·h） at 15 days after incubation. On the contrary,the highest activity of BG was 184. 46-207. 60 nmol/（ g·h） at 25 ℃ on the 3 rdand 75 thday,and the high temperature sensitivity of BG was observed at 15-25 ℃（ Q10= 1. 5）,while the cancelling effects of enzyme activity（ Q101） was observed both at 5-15 ℃ and 25-35 ℃,respectively. The change of soil enzyme activity was effected by multi-factors,and the increase of temperature stimulated soil microbial activities. As a result,temperature changed DOC and NH4＋-N content and exaggerated soil microbial biomass triggering changes in glucosidase activity. The study results quantified the temperature sensitivity of soil enzymes involved in the carbon conversion of paddy soil and their coupling with soil physical-chemical factors,which is of great significance for further carrying out the carbon cycle and regulation mechanism of paddy soil.