Accumulation of free amino acids in the tips of non-thermodormant embryonic axes accounts for the increase in the growth potential of New York lettuce seeds.

Accumulation of free amino acids took place only in growing axes during the first 24 hr of imbibition at 18°C. A ninhydrin-positive section was shown to be located at the tips of the axes by a histochemical technique. The amount of free amino acids accumulated just at the breaking of the seed coats in the non-dormant axes was great enough to account for the increase in the growth potential, i.e., the force to rupture the testa. About 72% of the accumulated free amino acids in the non-thermodormant embryonic axes was comprised of glutamine and glutamate.