EFFECTS OF CHITOSAN CONCENTRATION ON IN VITRO GROWTH OF DENDROBIUM HYBRID SEEDLINGS

Abstract

Chitosan is a reported plant stimulant. The objective of this work was to study the effect of chitosan on in vitro growth of Dendrobium hybrid seedlings. Two-month-old seedlings of Dendrobium 'White Pancy Lip' plants were sorted at the same size (approximately 1.2 to 1.5 cm in height) and were cultured on modified Vacin and Went (VW) medium supplemented with chitosan at the concentration of 10, 20, 40, 60 mg/L or without chitosan (control). Leaf numbers, the number of roots and the number of new shoots were recorded weekly. After 3 months, chitosan at 20 mg/L increased root number (1.68 roots per plant). Seedlings grown on VW supplemented with chitosan at 10 and 20 mg/L at week 11 had a higher leaf number compared with other treatments. The highest number of new shoots was found in VW media supplemented with chitosan at 20 mg/L. The effect of chitosan on the morphological characteristics of the adaxial leaf side showed that all chitosan treatments had a lower stomata number, but a larger stomata size compared to the control. On the abaxial leaf side, the concentration of chitosan did not affect stomata number and size, but chitosan at the concentration of 10 mg/L had the highest number of chloroplasts (31.1 chloroplasts) compared to other treatments.