华北平原冬麦田根呼吸对土壤总呼吸的贡献

Contribution of Root Respiration to Total Soil Respiration in Winter Wheat Field in North China Plain

用LI-6400便携式光合作用测量系统及LI-6400-09土壤呼吸室对冬小麦关键生长期农田土壤各组分呼吸速率进行了测定,并用根生物量外推法(RBE)和根去除法(RE)两种方法估算了根系呼吸对土壤总呼吸的贡献。结果表明:土壤各组分呼吸速率有明显的季节变化,土壤中根生物量解释了大约44%的土壤呼吸的季节变化;土壤各组分呼吸速率与5-10cm土壤温度关系密切,呈指数正相关,Q10值为1.4～1.6;用根生物量外推法(RBE)得到的根呼吸对土壤总呼吸的贡献为18%～54.3%、平均值为32%,比根去除法(RE)得到的贡献率(32.6%～58.1%)、平均值(44.6%)低。两种方法描绘的根呼吸季节变化趋势一致,且都在小麦花期表现出峰值。综合两种方法,得出华北平原冬麦田根呼吸对土壤总呼吸的贡献率为32%～45%。

Soil respiration rate of winter wheat was measured by using a LI - 6400 portable photosynthesis system and a LI - 6400 - 09 soil CO2 flux chamber at the Yucheng Comprehensive Experimental Station of the Chinese Academy of Sciences during the main growing season in 2008. The root biomass extrapolation method （RBE） and root exclusion method （RE） were adopted to estimate the contribution of root respiration to the total soil respiration respectively. The results showed that each of the different components of soil respiration had a clear seasonal variation, and the relationship explained 44% of the seasonal variation in soil respiration due to the variation in root biomass. There was a significant exponential correlation between soil respiration and the soil temperature at 5 - 10cm soil depth. The Q10 of 3 different components of the soil respiration was with 1.4 - 1.6. The contribution of root respiration to total soil respiration was estimated in the range from 18% to 54.3% with mean value at 32% by using RBE method, while it was from 32.6% to 58. 1% with mean value at 44.6% by using RE method which was lower than by RBE method. The trend of seasonal variation of root respiration was the same by two methods and the peak value was at the flowering period of winter wheat. The contribution of root respiration to total soil respiration of winter wheat had a range from 32% to 45% integrated by two methods.