N,N′-bis-(2,3-methylenedioxyphenyl)urea and N,N′-bis-(3,4-methylenedioxyphenyl)urea interact with auxin in enhancing root formation of M26 apple (Malus pumila Mill.) stem slices

Stem slices cut from micropropagated cuttings of apple rootstock M26 were cultured in the presence of indole-3-butyric acid (IBA) plus N,N′-bis-(2,3-methylenedioxyphenyl)urea or N,N′-bis-(3,4-methylenedioxyphenyl)urea, to verify if there was an interaction between them in enhancing root formation. The N,N′-bis-(methylenedioxyphenyl)ureas were supplemented after, before and in the simultaneous presence of auxin. Our data demonstrate that only the simultaneous presence of auxin and N,N′-bis-(methylenedioxyphenyl)ureas in the culture medium enhanced root formation on M26 stem slices. The percentage of rooted slices obtained in the presence of the mixtures was significantly different from that obtained in the presence of low auxin concentration alone (1µM). Moreover both the percentage of rooted slices and the number of roots per slice obtained in these culture conditions was not significantly different to that of the optimal auxinic treatment in which the auxin concentration was threefold higher.