Shoot regeneration from cotyledon explants of fibre flax (Linum usitatissimum) and their subsequent rooting

In this study, the morphogenic ability of cotyledon explants of fibre flax (Linum usitatissimum L.) was investigated in relation to their physiological age and genotype and the effect of growth regulators in the medium. Among four investigated genotypes, the explants of cvs. A-29 and Alexim manifested the highest and the lowest morphogenic ability, respectively. The optimum ratio of growth regulators for shoot regeneration was shown to depend on the age of donor plantlets from which the explants were obtained. For explants excised from younger plantlets, the lower concentration of benzyladenine (BA) and the absence of auxin were preferable. For explants from older plantlets, the higher BA concentration and NAA presence in the medium were required for shoot regeneration. The addition of ABA to the regeneration medium usually reduced shoot regeneration frequency; however, the inhibitory effect of ABA depended on other growth regulators.