1969 Volume 38 Issue 3 Pages 207-213
Because it has been known that azolides have generally higher chemical reactivity, the present authors synthesized TH-656[1-(α-naphthaleneacetyl) -3, 5-dimethylpyrazole] in expectation of new activity as a plant growth regulator, and compared biological activity of TH-656, NAA(α-naphthaleneacetic acid) and TH-564(3, 5-dimethylpyrazole).
The results obtained were summarized as follows:
1. TH-656 showed higher biological activity (both promotion and inhibition) on the growth of Avena coleoptile sections, the 2nd leaf sheath and coleoptile of intact rice seedlings thanNAAat the same molar concentration. At the existence of externally applied gibberellin, TH-656 showed more remarkable inhibition of the growth of the 2nd leaf sheath of rice seedlings than NAA. On the other hand, the growth inhibition of the 2nd leaf sheath of rice seedlings caused withNAAwas restored with gibberellin but the inhibition with TH-656 was not. TH-564scarcely showed a biological activity on the growth of Avena coleoptile sections and intact rice seedlings even at the high concentrations without any relation to the existence of externally applied gibberellin.
2. Then, the effcets of TH-656, NAAand TH-564on the gibberellin-induced parthenocarpic fruits of Delaware grapes were compared at the concentrations of 1/2n mM (n=0-4) on 20, 30 and 44 days after the full bloom. As a result, TH-656 and NAA retarded maturity of the grape fruits, but NAA did not retard uniformly the maturity among the fruit clusters on a tree and the berries on a cluster at the all concentrations used in the present experiment and TH-656 also fell to retard uniformly at the treatments after 20 and 44 days from full bloom, but at the treatment after 30 days from full bloom the maturity was remarkably retarded by spraying of solutions at the higher concentrations than 1/8mM, that is, desirably at 1/2 or 1mM. TH-564did not affect the maturity of the fruits at all concentrations used in the present experiment.
