Plant growth regulators used for somatic embryo induction
included 2,4-dichlorophenoxy acetic acid (2,4-D; 0.45–
18.1 μM), picloram (0–8.28 μM), and picloram (0–8.28 μM)
in combination with BA (0.22–4.44 μM). In order to study
the effect of age of the cultures on somatic embryo induction,
explants were isolated from 30-, 60-, and 90-d-old cultures
(after inoculation) and inoculated onto embryo induction
medium (MS medium supplemented with 4.14 μM picloram
and 0.22 μM BA). Similarly, the effect of long-term
multiplication cycles on somatic embryo induction potential
of explants was also studied. Explants were harvested every
second cycle from the 6th multiplication cycle until the 18th
cycle, and were inoculated onto MS medium supplemented
with 4.14 μM picloram and 0.22 μM BA. The time taken for
somatic embryo induction, the percentage of responding
explants, and the approximate number of somatic embryos
formed per explant were recorded at each harvest.