Developmental changes in the secondary xylem ofAcer rubrum induced by gibberellic acid,various auxins and 2,3,5-tri-iodobenzoic acid

Summary The effect of GA on the development of the secondary xylem ofAcer rubrum was studied. GA was applied to seedlings (1) separately, (2) simultaneously with TIBA, and (3) simultaneously with TIBA and an auxin. GA alone is without effect on the development of the secondary xylem. In seedlings treated with TIBA-GA or TIBA-GA-auxin, the differentiation of the xylem elements is in general similar to that of seedlings treated with TIBA or TIBA-auxin respectively. GA however, does stimulate cambial activity in a localized region of the stem if the endogenous rate of cambial division is low.The following abbreviations will be used TIBA (2,3,5-tri-iodobenzoic acid) - IAA (indole-3-acetic acid) - GA (gibberellic acid) - NAA (naphthaleneacetic acid) - 2,4-D (2,4-dichlorophenoxyacetic acid) This material was included in a doctoral thesis submitted by P. R.Morey to the graduate school of Yale University, New Haven.