氮肥施用对玉米根际呼吸温度敏感性的影响

为研究氮肥施用对玉米根际呼吸和土壤基础呼吸温度敏感性的影响,采用动态密闭气室红外CO2分析法,于2010年进行田间试验,该试验设4个处理：裸地不施氮肥（CK）、裸地施氮肥（CK-N）、种植玉米不施加氮肥（M）、种植玉米施加氮肥（M-N）,观测玉米田土壤呼吸各组分的日变化规律,同时观测土壤温度、气温等环境因子。结果表明,不种植玉米处理（CK和CK-N）土壤呼吸速率（土壤基础呼吸）为0.57～1.23μmol·m-2·s-1,施加氮肥对土壤基础呼吸没有显著影响;种植玉米条件下,施氮处理（M-N）的季节平均土壤呼吸速率为3.14μmol·m-2·s-1,显著高于不施氮处理（M）,增幅达31.9%。CK和CK-N处理的土壤基础呼吸温度敏感系数Q10分别为1.20、1.25,而不施氮和施氮条件下玉米根际呼吸的Q10值则分别为1.27、1.49。施加氮肥导致玉米根际呼吸温度敏感性明显增强（Q10值增大）,而土壤基础呼吸的温度敏感性则无明显变化,两种效应的叠加使得种植玉米土壤的总呼吸速率温度敏感性明显增加。

Effects of Nitrogen Fertilization on Temperature Sensitivity of Rhizosphere Respiration During Maize Growing Stages

Field experiment was carried out in 2010 in order to investigate the effects of nitrogen（N） fertilization on the temperature sensitivity of maize rhizospheric respiration and soil basal respiration during maize growing stages.Dynamic closed chamber infrared CO2 analysis was used to measure diel variation in soil respiration components during key growing stages.Environmental factors such as soil temperature and air temperature were also measured.Four treatments were set up in the experiment,i.e.,unplanted and N-unfertilized（CK）,unplanted but fertilized with 300 kg·N·hm-2（CK-N）,planted maize（Zea mays L.） but N-unfertilized（M）,and planted maize and fertilized with 300 kg·N·hm-2（M-N）.In unplanted soils（CK and CK-N）,soil respiration rate（soil basal respiration） ranged from 0.57 to 1.23 μmol·m-2·s-1,and N fertilization had less effect on soil basal respiration.On the other hand,in planted soils,the seasonal averaged soil respiration rate in M-N treatment amounted to 3.14 μmol·m-2·s-1,and was 31.9% higher than that in M treatment.This increment mainly occurred at tasselling and flowering stages.The Q10 values（temperature sensitivity coefficients） for unplanted treatments（CK and CK-N） were 1.20 and 1.25,respectively,while the Q10 values for planted treatments（M and M-N） were 1.27 and 1.49.N fertilization evidently increased temperature sensitivity coefficients of maize rhizospheric respiration,but had less effect on those of soil basal respiration.Thus,superposition of the two effects led to apparent increase in temperature sensitivity coefficients of total respiration rate in maize-planted field.