Abstract: 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.

Key words: Plutella xylostella, Pesticide, Life table