Propagation and cytotaxonomic studies in some Indian orchids

Abstract

Investigations to standardize propagation techniques in some Indian orchids and cytological studies in 15 species of Indian orchids belonging to five genera were carried out. Among five basal media (K.C., V.W., BN3F, M.S. and M) compared with regard to germination and growth of Spathoglottis plicate and Phaius wallichii. Vacin and Went’s (V.W.) medium proved to be the best in which germination of seeds was faster than in the others. Pseudobulbs of Dendrobium aggregatum treated with IBA at 1000 and 2000 ppm put forth maximum rooting, number of roots and root length. The effect of NAA at 2000 ppm on the Pseudobulbs was similar to that of IBA at 1000 and 2000 ppm. Cytotaxonomical studies showed that among the five species of Paphiopedilum (P.fairieanum, P.hirsutissimum, P.insigne, P.venustum and P.villosum) four species except P.venustum were found to be diploids with 2n=26. P.venustum possessed 2n=36 which may be hypoploid due to centric fission. In these species the chromosomes were large. All the three species of Cymbidium (C.aloifolium, C.giganteum, and C. grandflorum) possessed a chromosome number 2n=40 which represented a clear homogenous assemblage. In the genus Pholidota the species P.imbricate also had a chromosome number of 2n=40. In the genus Aerides all the species investigated (A.lawrence, and A.odoratum) possessed 2n=40 chromosomes. In Rhynchostylis the only species investigated R-retusa possessed 2n=38. It was concluded that both numerical and structural alteration in chromosomes have played an important part in the evolution of different orchid species, which got stabilized through the agency of vegetative reproduction. 125