ENDOGENOUS GROWTH REGULATORS IN RELATION TO SIDE SHOOT DEVELOPMENT IN THE TOMATO

Abstract

SummaryA study has been made of the endogenous factors controlling lateral bud initiation and development in the variety Craigella, and two isogenic lines of this variety, Craigella Blind (blbl) and Craigella Lateral Suppressor (isls), in both of which side shoot growth is suppressed to varying degrees. Winter‐ and summer‐sown plants are compared.Lateral Suppressor plants contained higher endogenous levels of auxin in their apices, mature leaves and stems than did normal plants, but lower level of cytokinins in all parts except the stem, where the levels were similar in both types. The levels of abscisic acid‐like substances were consistently higher in the stems of Lateral Suppressor plants than in the corresponding tissue of normal plants, but other plant parts showed a more variable pattern. Lateral Suppressor plants contained higher levels of gibberellin than did normal plants.Blind plants contained higher levels of auxin in the apices and stem than did normal plants, but the levels in mature leaves showed no consistent pattern. Higher levels of abscisic acid‐like substances were present in the stem and axillary buds of blind plants than in normal plants, with again a more variable pattern in other plant parts. The levels of cytokinins and gibberellins varied considerably between the two sowing dates.A possible hormonal mechanism of control of axillary bud development is discussed.