15Nitrogen Study on Accumulation and Allocation of Nitrogen Applied at Anthesis on Top of Early Nitrogen Applications in Winter Wheat

The objective of this experiment was to assess the effect of interaction between early and late nitrogen (N) fertilization on grain yield, protein content, and distribution of N between organs of winter wheat. Wheat was grown in pots in vegetation house. Experiment has been carried on in three years 2001–2003, each year in four replications. Wheat supplied with 0.9, 1.4, 1.9, 2.4, and 2.9 g N/pot was top dressed at anthesis by 0.85 g labeled nitrogen ¹⁵N/pot. Plants supplied with 0.9 g N/pot enhanced grain yield by 28% and gluten content by 62% and plant supplied with 2.9 g N/pot by 27% and 13%, respectively. The amount of ¹⁵N fertilizer stored in plant organs decreased proportionally to the amount of previously accumulated nitrogen, but the share of ¹⁵N in plant parts was almost constant. Grain accumulated about 86% of total ¹⁵N taken up by plants. Irrespective on nitrogen status prior to anthesis, about 50% of ¹⁵N has been used for gluten formation. The percentage of ¹⁵N recovery fraction ranged from 79% to 86%.