Studies on Endogenous IAA Levels and Adventitious Root Formation Capactity of Different Hypocotyl Segments of Cabbage

The capactity of adventitous root formation in different hypocotyl segments of cabbage was determined. It was shown that the different hypocotyl segment of cabbage may be defined as a spontaneous rooting system, which does not need inducement of any plant hormones. There is progressively increasing capacity of adventitious root formation from segment 1 to segment 5. IAA contents have been determined in different hypocotyl segments by an enzyme-linked immunosorbent assay (ELISA). We have also analyzed the relative activity of peroxidase (PER) and IAA oxidase in 5 kinds of segments. We have also studied the histology of the formation and development of adventitous roots in different hypocotyl segments of cabbage. The results show that the endogenous IAA level at time zero does not coincide with capacity of adventitious root formation of the different segment, and that initial cells which could be deve~loped primordium lie in the distinct phase of early stage of adventitious root initiation in the different hypocotyl segments of cabbage during their ontogenesis. We suggest that an inverse correlation between endogenous IAA contents and capacity of adventitious root formation may result from the facts that the first events of induction could already have overpassed a peak of IAA levels in spontaneous rooting segments of hypocotyls of cabbage.