CHANGES IN THE CONTENT OF GIBBERELLIN-LIKE SUBSTANCES IN RIPENING SEED AND POD OF

The amount of gibberellin-like substances in seed, pod, embryo and "endosperm " of Lupinus luteus in relation to their development was studied by means of the rice seedling test. The amount of gibberellin-like substances per seed increased remarkably at the first stage of development, when the growth of seed and pod was very slow, and attained its maximum at such an early stage as the dry weight of seed reached a value of only 10 per cent and that of pod 28 per cent of their respective maximum levels. Changes in amount of gibberellin-like substances present in the pod were very closely related to the changes in growth of pod. Gibberellin-like substances equivalent to Q.Z ̂ g gibberellin A3 per seed and 0.028 fig per pod were found at the 20th day after anthesis, and no activity in mature seed and 0.09 /ig per pod at the 50th day. No activity was found in the embryo itself at all stages, indicating that the gibberellin-like substances in seed occur only in the "endosperm, " i.e. in the tissues that will eventually form testa in fully ripened stage. The occurrence of gibberellin-like substances in many species of plants has been demonstrated (1). Early studies showed that immature seeds have relatively high activities of the substances (2-5). It would appear that the rapid growth of a seed might be associated with the native growth regulators in the seed. There appeared several papers on the study of the changes in amount of auxins (6-9) and gibberellin-like substances (10-13) during seed development. In the present experiments the relation between the content of gibberel-lin-like substances in fruit and seed tissues of Lupinus luteus and their development was investigated