Several reports on the occurrence of some growth inhibitor not only in
dormant seeds, buds and tubers, but also in the actively growing plant organs,
such as expanding buds, leaves and young fruits have appeared in the literature
(BENTLEY, 1958). Studying on germinating seeds, CARTWRIGHT et a1. (1956)
have extracted an acidic growth inhitbitor from germinating peas, var. Alaska.
It appeared at the earlier sampling times; its concentration decreased during the
first 3 days of germination; none was detected in the 72- and 96-hour extracts.
In the next few days of seedling growth, however, this inhibitor re-appeared.
PFIRSCH (1956) extracted a neutral growth inhibitor which controls the development
of the axillary bud, from cotyledons of Sinapsis alba seedlings. POL]
AKOFF-MAYBER et a1. (1957) have also reported the appearance of an acidic
growth inhibitor in germinating lettuce seeds at about 24-48 hours after incubation.
MURAKAMI (1960) reported the occurrence of gibberellin in dry seeds
and in growing shoots of rice plant. He (1961) also observed that gibberellin
and acidic growth inhibitor are contained in the young seedlings of Pharbitis
Nil germinated in the dark.
The present writers found an abundant accumulation of a neutral growth
inhibitor in the endosperms of rice seeds durfng germination. As it was
assumed that this inhibitor might be correlated with the sluggish growth at the
early stage of rice germination, studies were made on the physiological role of
this growth inhibitor obtained from germinating rice seeds and at the same time
some observations were carried out to ascertain the effect of the gibberellin-like
substance obtained from such rice seeds on the growth of wheat leaf sections.