THE ROLE OF AUXIN IN THE PHOTOPERIODIC TUBERIZATION IN BEGONIA EVANSIANA ANDR

概要

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The formation of aerial tubers in Begonia plants, an SD response, was inhibited by IAA, NAA and IBA applied to their leaves during the dark periods. The effectiveness of IAA differed according to the time of application during the dark periods, and the most sensitive time varied with daylengths employed. In order to inhibit the tuberization under optimal photoperiods (8-hr SDs), IAA had to be applied during the first 2 days or so of the SDs. Under non-optimal photoperiods, however, IAA was effective even when applied somewhat later. The auxin activity of leaf extracts from the plants subjected to 8-hr SDs decreased during the first 2 or 3 days to a minimum, and then increased until finally began to decrease again ; under non-optimal photoperiods, the minimum of auxin activity was attained more slowly. The paper-chromatographic study suggested that the change in auxin activity was mainly due to the change in IAA content. The number of SDs making the auxin content minimal agreed with the minimum number of SDs required for tuberization. On the basis of the above results, the part played by endogenous auxin in photoperiodic induction is discussed.
日本植物生理学会の論文