The effects of Peptone and silver nitrate (AgNO3) on in vitro shoot formation from cultured
shoot tips of Hevea brasiliensis seedlings raised ex vitro were investigated. The addition of
silver nitrate at concentrations of 3-5 mg/l to the shoot induction medium (SIM; Murashige and
Skoog (MS) + 5 mg/l 6-Benzyladenine (BA) + 0.5% activated charcoal + 3%sucrose + 0.75%
agar(, induced multiple shoot formation in all the explants at mean rates of between 2 and 3
shoots per explant. However, the mean numbers of shoots per explant were not significantly
different (p < 0.05) among all the concentrations tested nor were they significantly different
from the mean number of explants raised in a control medium without silver nitrate
supplementation. When the concentration of silver nitrate was decreased to 0-2 mg/l, the
number of shoots per explant improved. The best results were achieved using a medium
containing 1 mg/l silver nitrate in which a mean number in excess of 5 shoots per explant was
obtained, the shoots having dark green leaves and vigorous growth, while those obtained from
the medium without silver nitrate supplementation were pale green, and senescence of leaves
was found after they had been cultured for 4 weeks. The addition of peptone (0-2%) was not
successful in inducing multiple shoots. The number of shoots per explant decreased in
comparison with the control treatment. Some shoots developed in the peptone-containing
medium were small with senescence of leaves occurring after being cultured for 4 weeks.
Key words: Peptone, Silver Nitrate, Multiple shoot formation, Hevea brasiliensis