Dark germination of Amaranthus hypochondriacus seeds was studied in relation to the influence of certain growth regulators under different light-quality conditions. The experimental results were briefed as in the following compendia;
1. Under the light conditions of cool white fluorescent lamps, the germination was fairly promoted in a low to relatively high concentrations of ethephon. In high concentrations, the germination was still promoted almost as much as in the case of the level of dark condition when observed 24-hour period after seeding, while the effect somewhat died off 48 hours after seeding, but their root (radicle plus hypocotyl) elongations were considerably inhibited.
2. The germination was fairly promoted in low concentrations of GA in the light condition which generally inhibits the germination, but in high concentrations, the germination and root elongation were also inhibited. With various concentrations of either NAA or BA, the germination was also inhibited, and exhibited no apparent overcoming effect of the light inhibition.
3. Concurrent treatments of ethephon and GA showing these interactions toward a promotion of the germination under light conditions showed no synergistic action more than either treatment alone.
4. Germination was promoted with the treatment of ethephon or GA under red light more than either treatment of red light alone, and strongly inhibited under far-red light, was considerably overcome by the treatment of ethephon and less so by GA.
5. The promotive ethephon effect on light-inhibited germination of Amaranthus hypochondriacus seeds is assumed due to a reduction of the inhibitory action of phytochrome (Pfr in this case) and promotion in physiological metabolism exerted by ethylene.
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