Studies on the growth and fruiting in the tomato. VIII

Abstract

The changes of carbohydrate, nitrogen, auxin, gibberellin and nucleic acid metabolism associated with the transition of tomato plant from the vegetative to the reproductive state in response to the environmental and cultural treatments were investigated in this report, with the aim of finding the causal physiological factors for the flower formation.1. Relationships between nitrogen and carbohydrate metabolism and the flower formation.Carbohydrate and nitrogen compounds gradually increased with the progress of plant growth and reached to their peaks just before the flower bud differentiation of plant grown at each condition, and then decreased with the development of flower bud.2. Relationships between auxin metabolism and the flower formation.The content of auxin in the apical parts of plants grown under the natural conditions was large at the vegetative stage and temporarily decreased just before the flower induction, and then increased considerably after the flower induction.3. Relationships between gibberellin metabolism and the flower formation.Seasonal trend of gibberellin-like substances in the apical parts of plants grown under the natural conditions was the same as that of auxin.4. Relationships between nucleic acid metabolism and the flower formation.DNA content was fairly constant in the apical parts of plants grown at various conditions during the course of vegetative growth, but thereafter gradually increased following flower induction, while RNA content in the apical parts of plants grown at various conditions increased rapidly with the progress of the plant growth, reaching to a peak immediately before flower initiation, corresponding with the time of a temporary decline of auxin, and then decreased after flower induction.5. Relationships between the various constituents and the flower formation.From the previous papers and the present results it may be explained as follows:Auxin and gibberellin in the apical bud and/or the immature leaves exerted an effect to pull the stream of the flower forming substances from the mature leaves, and the amount of the flower forming substances supplied to the meristematic tissues varied being controlled by the level of auxin and gibberellin in the apical bud and/or the immature leaves. The lower level of auxin and gibberellin in the apical bud and/or the immature leaves affected to promote the accumulation of the flower forming substances in the meristematic tissues. The reproductive DNA (gene for flower formation) in the meristematic tissues had to duplicate and was activated by the flower forming substances accumulated in the meristematic tissues, and the activated reproductive DNA transcribed the genetic code to the reproductive RNA, and the specific reproductive protein was produced in the meristematic tissues under the guiding auspices of the messenger RNA, and the cell division in the meristematic tissues caused by the action of the reproductive protein and induced the flower formation.