Micropropagation of Crossandra infundibuliformis Nees cultivar ‘Mona Wallhead’
Crossandra infundibuliformis is a major herbaceous ornamental, normally used to form flower beds. However, Crossandra
diffusion is limited by the difficult propagation. This study aimed to evaluate the effects of different plant hormones on bud
induction and root formation of Crossandra explants, in order to develop a reliable protocol toward the propagation of the
specie. For bud induction nodal segments of Crossandra germinated in vitro were cultivated in medium containing 0.5 mg
L-1 of three cytokinins: kynetin (KIN), 6-benzylaminopurine (BAP), and 2-isopentenyladenine (2iP) essayed either alone
or combined, totaling eight treatments as follows: T1 - control; T2 - KIN; T3 - BAP; T4 - 2iP; T5 - KIN + BAP; T6 - KIN +2iP; T7 - BAP + 2iP and T8 - KIN + BAP +. 2iP. 16
replications (plants) per treatment were used in a complete randomized
design. For root formation, explants were cultivated in MS medium (50%) added indolbutiric acid (IBA) in the concentrations
as follows: 0.0, 0.25; 0.50; 0.75 and 1.00 mg L-1. The number of treated explants presenting buds and bud average per
treated explants increased with time. Upon the 60th day of cultivation, all treatments containing BAP averaged a higher
number of buds per explant principally the one in which BAP was applied alone. That treatment presented the highest bud
proliferation rate (12.9 buds/1 explant) followed by the treatment BAP + KIN, which presented the second best rate (11.4buds/ 1 explant)
and showed buds with higher quality. The greatest percentage of rooting explants (60%) was achieved
with IBA 0.5 mg L-1. It was also observed that the increase in root average per explant was proportional to the increase in
concentration of IBA. The results led to the conclusion that BAP 0.5 mg L-1 is more efficient to induction of multiple buds
on explants than the others tested cytokinins, applied either alone or combined. The best IBA concentration regardingrooting promotion was 0.5 mg L-1
.