华北高产农田生态系统中冬小麦分蘖期生长与碳截留

模拟华北高产施肥条件盆栽冬小麦，采用^14C同位素对分蘖期冬小麦进行脉冲标记，并分别在分蘖期、拔节期、花期和成熟期取样测定冬小麦地上部、根和土壤中的^14C含量，研究冬小麦光合固定碳对土壤碳库的输入机制。结果表明：冬小麦冬前植株地上部分的生长可以用三次方程较好地拟合；冬小麦出苗后36d停止生长，植株地上部分平均干质量为0．219g·株^-1，折合为0．09gC·株^-1。冬小麦分蘖期光合固定的碳在植株地上部分、地下根部和土壤中的分配比例分别占光合同化HC总量的35.2％、10．4％和51．3％。到冬小麦生长期末，植株地上部分、地下根部和土壤中的^14C含量分别降至最初光合同化^14C总量的3．9％、4．6％和26．4％。通过呼吸作用所释放的^14C总量随作物生长时间的推移不断增大，到生长期末，通过呼吸作用输出的^14C的量占分蘖期冬小麦固定总量的65．2％。

Growth and carbon sequestration of winter wheat at its tillering stage in high yield farm ecosystem of North China

In a pot experiment with simulated high yield conditions of North China, winter wheat plant was pulse-labeled with 14C at tillering stage, and the 14C content in wheat shoot and root and in soil was measured at tillering, elongation, anthesis, and dough stages, aimed to study the mechanisms of soil carbon input through winter wheat growth. The results showed that the shoot growth before winter could be well fitted by cubic function. Thirty-six days after emergence, the average shoot dry weight was 0. 219 g per plant, amounting to 0. 09 g C per plant. The proportion of 14C in shoot, root and soil two days after labeling was 35.2%, 10. 4% and 51.3% of the total assimilated 14C, and declined to 3.9%, 4.6% and 26. 4% by the end of growth season, respectively. The 14C amount emitted by respiration increased with plant growth. By the end of growth season, the 14C output from respiration accounted for 65.2% of the total 14C fixed at tillering stage.