APPLICATION OF CHITOSAN ON IN VITRO GROWTH OF RHYNCHOSTYLIS GIGANTEA PROTOCORMS AND SEEDLINGS

Abstract

One-month-old protocorms of Rhynchostylis gigantea (approximately 20 to 30 mm in diameter) derived from in vitro seeds propagation were cultured on modified Vacin and Went (VW) medium supplemented with chitosan at the concentration of 0 (control), 10, 20, 40 and 60 mg/L for two months. After this only seedlings that had one leaf with 1 or 2 roots were selected and sub-cultured on to the same medium and further sub-cultured every month for 6 months. Growth of the protocorms was measured every 2 months. Seedlings cultured on VW supplemented with 60 mg/L of chitosan for two months had the highest number of leaves (3.6±-0.25). Whereas, the seedlings cultured on VW supplemented with chitosan at 40 mg/L had the highest number of roots (4.0±0.71). After four months, seedlings cultured on VW supplemented with 40 mg/L of chitosan had the highest leaf length, leaf width and leaf area (2.2±0.19, 0.7±0.05 cm and 1.4±0.19 cm 2 , respectively). Six months after culture, seedlings cultured on VW supplemented with 40 mg/L of chitosan had the highest stem fresh and dry weight and number of roots (1.452±0.16, 0.082±0.01 g and 7.5±0.47, respectively). VW supplemented with 10 mg/L of chitosan increased the number of leaves, plant height and root dry weight (4.3±0.12, 1.3±0.08 cm and 0.084±0.01 g, respectively). While seedlings grown in VW supplemented with 20 mg/L of chitosan had the longest root length (2.3±0.27 cm). However, there was no seedling survived in VW supplemented with 60 mg/L of chitosan after 4 months cultured.