水分调控对水稻根际土壤反硝化作用的影响

Effects of Three Different Irrigation Cultivated Modes on Soil Denitrification of Rice Rhizosphere

以水稻农田生态系统为研究对象,采用室内盆栽试验,研究干湿交替、浅水层连续灌溉以及控水3种水分管理模式引起的水分变化对水稻根际土壤反硝化作用过程的影响。结果表明:浅水层连续灌溉模式下的反硝化强度、反硝化速率、反硝化势的平均值为2.19mg/(kg·d),118.54mmol/(m2·d),28.42mol/(m2·d),而干湿交替模式以及控水模式下,反硝化强度平均值仅为连续灌溉模式的64.40%,52.34%,反硝化速率平均值为连续灌溉模式的69.02%,59.73%,反硝化势平均值为连续灌溉模式的77.39%,81.43%,即3种水分管理模式下,水稻根际土壤反硝化强度、反硝化势以及反硝化速率均表现为连续灌溉>干湿交替>控水模式。随着水稻的生长,3种水分管理模式下的水稻根际土壤反硝化强度、反硝化势以及反硝化速率均呈现递减趋势,表现为分蘖期>孕穗期>成熟期;相关分析表明,根际土壤反硝化强度、反硝化势及反硝化速率与系统中NO-3浓度有显著相关性,由此可见,3种水分模式下,水分及其植物生长导致底物NO-3浓度的差异是影响水稻根系土壤反硝化作用过程的因子。

A typical rice field ecosystem was selected as the research site.We used the indoor pot experiment to study the effects of three kinds of water cultivated modes（shallow layer of continuous irrigation,C;alternating wet and dry,J;water control mode,G）on soil denitrification of rice rhizosphere.The results showed that the average value of denitrification intensity,denitrification rate and denitrification potential in continuous irrigation groups were 2.19 mg/（kg·d）,118.54 mmol/（m^2·d）and 28.42 mol/（m^2·d）,respectively.The average value of denitrification intensity in alternating wet and dry groups and water control groups were64.40% and 52.34% of those in the continuous irrigation groups;the average value of denitrification rate in alternating wet and dry groups and water control groups were 69.02% and 59.73% of those in continuous irrigation groups;the average value of denitrification potential in alternating wet and dry groups and water control groups were 77.39%,81.43% of those in continuous irrigation groups,which indicated that the order of denitrification intensity,denitrification rate and denitrification potential of rice rhizosphere soil was continuous irrigation groups〉alternating wet and dry group〉water control groups.In addition,the values of denitrification intensity,denitrification rate and denitrification potential presented the obvious decreasing trend with the plant growth,and their orders were all tillering stage〉booting stage〉mature period.Correlation analysis showed that the rhizosphere soil denitrification intensity,denitrification potential and denitrification rate were significantly correlated with nitrate nitrogen concentration in the system.