Effect of explants type, light and polysaccharides on micropropagation of Catasetum orchid (Catasetum fimbriatum, L.)

The aim of present study was to investigate the effect of explants types, in light and darkness condition on propagation of lateral plantlets and also to investigate the effect of type and concentrations of carbohydrates on the regeneration of Catasetum orchid plantlets in two experiments. First experiment for propagation of lateral plantlets was done with two types of explants, shoot tips and root tips, in combination with different lighting conditions (light and darkness) in completely randomized design with 5 replications. According to obtained results, the production of leaves, roots, lateral plantlets and the intensity of explant necrosis were affected by explants types and environmental conditions of light and darkness treatments and were statistically significant at (p ≤ 0.01 & 0.05). The highest mean number of leaves (21.4), roots (5) were from shoot tip explants in light and the highest mean number of lateral plantlets (17.8) observed in root explants in darkness. In second experiment, the effect of different concentrations of sucrose and mannitol were investigated on the regeneration of Catasetum orchid plantlets. Experimental treatments were three levels of sucrose, 20, 30, 40 g/l, two levels of mannitol, 10.08 and 22 g/l in combination with 20 g/l of sucrose and mannitol alone at 10.08 g/l concentration. The highest mean number of formed lateral plantlets from each explant were 10.48 which were obtained at 30 g/l sucrose concentration. For production and growth of protocorm like body, all mannitol concentrations were better than sucrose and the highest protocorm like body mean number (1.54) were produced in 10.08 g/l mannitol concentration. In general conclusion, the highest lateral plantlets regeneration occurred from root explants in darkness treatment by using sucrose.