Abstract: The level of/various amino acids in rice embryos rose sharply during embryo differentiation (7–9 days after anthesis). Then it increased steadily or tended to become stable at mid-maturation stage (13–18 days after anthesis), thereafter continuing to increase, except that the contents of aspartate and glutamate decreased significantly. The total free amino acid pool expanded rapidly during the differential stage. There after the pool capacity showed only a slightly increase until the end of embryogenesis. Both on embryo cell and dry weight bases, the capacity reached the maximum at the 9th day after anthesis, then decreased at the 13th day, and later remained stable. We deemed that the establishment of the free amino acid pool is one of the events which occur in the process of rice embryo differentiation. By the fulfillment of the differentiation (the 13th dray after anthesis), the pool capacity within the embryo cells remained stable on the whole. The free amino acid pool was dominated by serine, alanine, aspartate and glutamate during the differentiation stage. In the maturation stage, serine, alanine, arginine and lysine were the main components. These predominant; amino acids may play an important role in regulating the availability of the whole amino acid pool.

Key words: Oryza sativa embryos, Free amino acid pool, Embryogenesis