Understanding the effects of crop growth stage on root respiration (RA) and its temperature sensitivity (Q10) has important theoretical and practical significance for enriching the carbon cycle theory of cropland. In a rain-fed agricultural ecosystem on the Loess Plateau, soil respiration rates were in situ measured in adjacent bare soil (soil microbial respiration, RH) and non-fertilized winter wheat (soil respiration, RS=RA+RH) with an automated CO2 flux system from 2009 to 2014 to investigate the effect of growth stage on RA and Q10. The results showed that net photosynthetic rate in the seedling, elongating, filling, and the ripening stage was 5.9, 14.4, 12.0, and 4.4 μmol·m-2·s-1, and the corresponding root activity was 51.0, 100.8, 84.4, and 31.8 μg·g-1·h-1, respectively. RA differed significantly among different growth stages, which was 0.26, 0.67, 0.91, and 0.56 μmol·m-2·s-1. The variation of RA was closely related with soil moisture, soil temperature, net photosynthetic rate, and root activity, which presented parabolic, exponential, linear, and linear models respectively. Furthermore, Q10 in each stage was 2.61, 4.88, 2.26, and 6.93, respectively, the variation of which was closely related with net photosynthetic rate, root activity, and soil moisture, with the contribution rate of root respiration being 29%, 53%, 46% and 31%, respectively. In conclusion, in addition to environmental factors, growth period of winter wheat was an important factor affecting RA and Q10.
研究农作物生育期对根系呼吸(RA)及其温度敏感性(Q10)的影响对丰富农田生态系统的碳循环理论具有重要理论和现实意义.在黄土高原雨养农田生态系统,于2009—2014年生长季,利用土壤碳通量系统测量相邻裸地土壤微生物呼吸(RH)和不施肥小麦地的土壤呼吸(RS=RA+RH),研究生育期对冬小麦RA和Q10的影响.结果表明:冬小麦净光合速率在苗期、拔节期、灌浆期和成熟期分别为5.9、14.4、12.0和4.4 μmol·m-2·s-1,根系活力依次为51.0、100.8、84.4和31.8 μg·g-1·h-1.冬小麦不同生育期的RA差异显著,分别为0.26、0.67、0.91和0.56 μmol·m-2·s-1,且RA的变异特征与冬小麦各生育期内土壤水分含量、土壤温度、净光合速率和根系活力密切相关,分别呈抛物线、指数、线性和线性关系模型.Q10在苗期、拔节期、灌浆期和成熟期分别为2.61、4.88、2.26和6.93,且Q10的变异特征与冬小麦各生育期内的净光合速率、根系活力和土壤水分含量有关,这一变化的根系呼吸贡献率在各生育期分别为29%、53%、46%和31%.除了环境因素外,冬小麦生育期也是影响RA和Q10的重要因素.
Keywords: growing season; soil temperature; temperature sensitivity of autotrophic respiration; winter wheat growth stage.