[Effects of nitrogen application level on photosynthate distribution of Korla fragrant pear trees].

Using C pulsed labeling technique, we examined the biomass and carbon accumulation of different organs as well as the distribution characteristics of C assimilate of 6-year-old Korla fragrant pear trees under three nitrogen application levels, ., 150, 300, and 450 kg N·hm (marked as N, N, and N, respectively). Results showed that the biomass, carbon accumulation, C fixation and leaf assimilation capacity of the whole pear tree increased while root to shoot ratio decreased with increasing nitrogen application. Both biomass and carbon accumulation amount of reproductive organs (., fruits) were the highest under N treatment. The C content and distribution rate of each organ changed dynamically along with increasing nitrogen application. At the new shoot growing stage, leaves and roots had stronger competitive abilities for photosynthate, with C distribution rates being the highest under N treatment. During fruit swelling and mature stages, leaves and fruits were more competitive, with C content and distribution rate in leaves being the highest under N treatment and those in fruits being the highest under N treatment. According to the absorption and distribution characteristics of carbon assimilate across organs under the three nitrogen application levels, the optimal nitrogen application level for achieving high fruit yield in the 6-year-old Korla fragrant pear tree orchard is recommended as 300 kg·hm .