Estimating the efficiency of different explants for directin Vitromultiple shoots development in chrysanthemum

Different explants of local chrysanthemum cultivars available in West Bengal including leaf, shoot tip and ray floret were employed to compare their efficiency for direct in vitro regeneration system. The explants were inoculated in Murashige and Skoog (MS) media supplemented with varied combinations of indole acetic acid (IAA), benzylaminopurine (BAP). The auxins indole -3-butyric acid (IBA) was used to induce rooting. Maximum multiple shoots production occurred at 1.0 mg/L BAP and 0.1 mg/L NAA for leaf explants, 2.0 mg/L BAP and 0.2 mg/L NAA combination for shoot tip explants and BAP (4.0 mg/L) + NAA (0.1 mg/l) for ray floret explants. Among the treatments, IBA 1.0 mg/L for both leaf and shoot tip regenerated plants and 0.5 mg/L for ray floret regenerates proved to be the best for promoting root regeneration as compared to the other treatments tried. Among the various carrier substrates tested for acclimatization, soil + sand + FYM (1:2:1) fortified with ½ strength MS plant salt mixture proved to be ideal substrate as maximum plant survived and a maximum of 82.3% survivability was obtained from shoot tip derived plantlets. Therefore, shoot tip explants are the most suitable type of explants for plant regeneration of chrysanthemum through direct somatic embryogenesis. However, direct plant regeneration through ray floret explants will also be useful to recover the flower colour mutants.