Abstract
It is reported in this paper that the lamina-joint test, which is a method to measure the extension of lamina joints, is available for the bioassay to estimate the actions of growth inhibitors. To explore a suitable test condition responding for IAA and IBA, the store conditions of seeds and the culture conditions of seedlings were took into consideration. But the influence of such conditions on the extension was little or no. It has been proved that the pretreatment period of 24 hours, in which the excised leaf segments were floated in deionized water, is enough for increment of the response to growth substances. The inhibitive effects of many substances on the extension induced by auxin were compared, by floating the segments for 48 hours in the combined solutions of various concentrations of the test substances and 10 mg/l of IAA after they were pretreated by deionized water for 24 hours. It is interesting that the inhibitive action shows less angles than the angular degrees of the segments which were floated in deionized water alone. It may be considered to be a phenomenon resulted from some drastic actions of those inhibitors rather than a physiological one.
