RESUMO
To understand the correlation between nitrogen fruiting efficiency and nitrogen utilization and remobilization in winter wheat, the differences and mutual relationships of nitrogen fruiting efficiency, nitrogen utilization and remobilization of winter wheat at different sowing dates (S1:24 September, S2:1 October, S3:8 October, S4:15 October and S5:22 October) were analyzed in two growing seasons from 2014 to 2016. The results showed that there was no significant difference in grain yield and grain number per unit area among different sowing dates. Delayed sowing date decreased nitrogen accumulation in both shoots and spikes, and then reduced nitrogen uptake efficiency and increased nitrogen utilization efficiency and nitrogen fruiting efficiency. Nitrogen fruiting efficiency was positively correlated with nitrogen utilization efficiency, negatively correlated with nitrogen uptake efficiency, but not significantly correlated with nitrogen use efficiency. Nitrogen nutrition index tended to be optimum with delayed sowing dates, showed synchronicity with the improvement of nitrogen fruiting efficiency. Pre-anthesis nitrogen remobilization amount in vegetative organs and post-anthesis nitrogen accumulation amount significantly decreased with postpone of sowing dates, but pre-anthesis nitrogen remobilization efficiency remarkably rise. There was a positive correlation between nitrogen fruiting efficiency and nitrogen remobilization efficiency, indicating that the improvement in nitrogen remobilization efficiency facilitated the increment in nitrogen frui-ting efficiency. Taken together, properly delayed sowing date reduced nitrogen uptake, but increased nitrogen utilization efficiency and nitrogen fruiting efficiency and improved nitrogen supply status, which provided a theoretical basis for the implementation of reducing input and improving nitrogen utilization efficiency in wheat production in this region.
