Pseudomonas fluorescent and its ability to promote root formation of olive microshoots

Root formation and root architecture of olive microshoots, inoculated or not with Pseudomonas fluorescent P19 or P21, were evaluated by measuring of length and the numbers of adventitious and lateral roots. Three-four nodal in vitro shoots were treated with different population densities (0, 105, 108 CFUml-1) of rhizobacteria. The density of 108 CFUmgl-1 induced almost two times increase in number and length of roots per explant, in contrast to that achieved by 105 CFUml-1. Both strains depending on the L.Tryptophan concentration of the bacterial media, strongly affected root growth and architecture. By application of L. Tryptophan up to 10mgl-1 in the media, the length and numbers of adventitious and lateral roots were increased. Bacterial treatments were more efficient than IBA. Moreover different inoculation methods revealed that co-inoculation of the soil and microshoots increased the numbers and length of the roots.