AbstractIn an experiment with three winter wheat (Triticum aestivum L)varieties (Splendeur, Hobbit and Maris Huntsman) cultivated after anthesis in a growth chamber, the upper part of the ear was removed on several dates after anthesis (halving). The remaining grains accumulated more nitrogen, especially between days 5 and 25 after anthesis; the increase depended on variety, the date of halving and the stage of development. The relative composition of the protein was also affected, since the amino acid composition of the grain varied. In the remaining grains the relative amounts of glutamate and, in general after 15 days, those of proline and phenylalanine increased; by contrast those of aspartate, lysine and arginine, among others, decreased. The response of the three varieties was similar. At maturity, the magnitude of the response was related to the variations occurring in the nitrogen (% DW). The stage of development in which the grain accumulated nitrogen supplement did not affect the regressions between the relative amounts of each amino acid and the nitrogen (% D W). However, when the ears were halved on day 25 after anthesis, the relative amounts of glycine, lysine and arginine tended to be slightly higher, especially in the case of Hobbit, than the values that would correspond to these regressions. The departure from regression increased with increasing accumulations of nitrogen in the grain between day 25 and maturity.