Abstract: The effects of chitosan, a biodegradable polymer,
were studied in Grammatophyllum speciosum protocorm-like bodies
(PLBs) in vitro culture. The chitosan concentration of 0, 5, 10, 15,
20, 25, 50 or 100 mg/l were supplemented in half-strength Murashige
and Skoog (1/2 MS) liquid or on agar media containing 2% (w/v)
sucrose. The results showed that liquid medium supplemented with
15 mg/l chitosan showed the highest relative growth rate (7-fold
increase) of PLBs. On 1/2 MS agar medium supplemented with 25
mg/l chitosan gave the highest relative growth rate (4-fold increase).
The relative growth rate of G. speciosum PLBs on agar medium was
significantly lower than that in liquid medium. Moreover, chitosan,
supplemented to agar medium promoted shoot formation but not
rooting. However, supplementation at too high a level, such as 100
mg/l can inhibit growth and kill PLBs.