Variation and long term regenerative capacity of two important tropical forage legumes: Cavalcade (Centrosema pascuorum cv. Cavalcade) and Stylo 184 (Stylosanthes guianensis CIAT184) in vitro

Shoots of Cavalcade (Centrosema pascuorum cv. Cavalcade) and Stylo 184 (Stylosanthes guianensis CIAT 184) from in vitro germinated seeds were cultured on Murashige and Skoog (MS) medium supplemented with 0 to 7 mg L-1 N 6-benzyladenine (BA) in combination with 0 to 0.5 mg L-1 napthalene acetic acid (NAA) for shoot induction and MS supplemented with 0 to 0.5 mg L-1 indolebutyric acid (IBA) for root induction. For Cavalcade, the medium containing 1 mg L-1 BA produced the best shoot multiplication with an excess of six shoots produced from a single shoot (over four weeks) with a mean height 2.0 ± 0.01 cm. Adventitious shoot regeneration was obtained directly from stem axes. For Stylo 184, the maximum shoot regeneration (29.5 ± 1.0 cm shoots/explant) and height (1.5 ± 0.1 cm) was achieved using 7 mg L-1 BA and 0.01 mg L-1 NAA. Direct and indirect shoot regeneration was obtained on the medium containing 1 mg L-1 BA and 0.01 mg L-1 NAA. The regeneration of shoots from callus of Stylo 184 varied between different genotypes and was high (2.6 to 5.8 shoots/explant) even after maintenance in culture of over three years. Both Cavalcade and Stylo 184 shoots were rooted on media supplemented with IBA (0 to 0.5 mg L-1) and readily transferred to soil (Stylo 184).   Key words: Callus, forage legume, micropropagation, organogenesis, root induction.