The study was designed to evaluate the comparative effect of IAA, NAA,
BAP & Kinetin on callus formation in Tagetes erecta. (marigold). Strength of
hormones was maintained at 0.1 to 1.0 mg/L in all cases. Explants used were
petiole, leaf blade, internode, node and root.
Callus development with three parameters were studied i.e. callus
initiation (in days), callus colour and callus texture (Table 1). Callus formation
was observed in all explants except roots under all experimental conditions.
In IAA explants responded by initiating callus in all IAA concentrations
except 1mg/L. In 1mg/L only petiole and leaf developed callus whereas internode
and node did not respond. Maximum explants initiated callus formation in 20 day.
The callus initiation process decreased when time period was increased or
decreased from 20 days. Minimum days recorded were 17 days when leaf blade
developed callus whereas maximum days consumed for callus initiation were
taken by node were 24. In all explants callus colour was green or shades of
green. Mostly it was green (14 readings) followed by yellow green (4 readings)
light green (3 readings) and bright green (1 readings only). Texture of the callus
was explant oriented. Under all IAA concentrations, explants petiole and leaf,
produced granular callus whereas internodes and nodes produced compact
callus.
At all NAA strengths all explants initiated callus formation except
internode which did not respond at NAA 0.9mg/L. Minimum time taken for callus
initiation was 20 days by leaf blade while maximum time was 27 days taken by
nodes. In all callus, colour was green or shades of green as in IAA. Mostly it was
green (14 readings) followed by light green (7 readings) and yellow green (3
readings). Texture of the callus was again based on explant used. Petiole and
leaf produced granular callus whereas internodes and nodes produced mostly
compact callus.