The present experiments were designed to determine the responses of hypocotyl elongation with and without cotyledons after germination, as modified by administrating various growth regulators, such as GA, IAA, B-9, Ethrel, Quel, RH-531, MH, amino acids and vitamins to Impatiens balsamina, and to study interaction among the growth regulators used. GA treatment alone without intact cotyledons promoted hypocotyl elongation as significantly as that with intact cotyledon alone, while respective treatment of either B-9, Quel, RH-531, Quel and Ethrel were postulated as being antagonistic to the GA action.
IAA alone did not indicate the effect of elongation, whereas GA plus IAA treatments did show a significant effect. It was postulated that IAA and GA act mutually synergistic. Combined treatments of GA with amino acids and vitamins resulted in a greater effect on elongation than the treatment made respectively alone, while GA acted greatest on the elongation.
It was therefore feasible to sec that elongation of balsam hypocotyl is due largely to the influence of GA drived from intact cotyledons.
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