MSc

Orchids occur mainly in humid tropics and temperate regions of the world. They are known for their long lasting and bewitchingly beautiful flowers. Out of the nearly 30,000 species of orchids in the world, India contributes around 1200 species. In India, the north eastern region accounts for about 800 species, while the Western Ghats has around 275 species of orchids.
Western Ghats is one among the 34 biodiversity hotspots identified in the world. However, due to the continuing loss of habitat, fragmentation, expanding human population and other activities, some of the flora and fauna in this region are included in the highly threatened group, orchids being one among them. Many of the orchids in this region are indiscriminately exploited for the local traditional medicine and for horticulture purpose and thus face the danger of being extinct. Hence the present study was undertaken in order to assess the orchid diversity in selected regions in Central western Ghats and to conserve few genotypes which are threatened.
The study on “Characterisation and conservation of promising genotypes of orchids from Central Western Ghats” was carried out at Central Western Ghats and College of Agriculture, Padanakkad, Kasargod, Kerala during 2014-2016. The study was based on the survey carried out in 6 natural habitats of Central Western Ghats namely Aralam Wildlife Sanctuary, Ranipuram Wildlife Sanctuary, Pushpagiri Wildlife Sanctuary, Brahmagiri Wildlife Sanctuary, Talakavery Wildlife Sanctuary and Rajeev Gandhi National Park. The survey revealed that, a total of 9463 accessions of orchids belonging to 70 species classified under 30 genera were present in these habitats. Among these, maximum number of orchid genera was recorded from the Brahmagiri Wildlife Sanctuary (23 genera, 39 species), whereas minimum in the Ranipuram Wildlife Sanctuary (15 genera, 22 species). The diversity analysis was made by using Shannon Index (H') and Simpson Diversity Index (D). The highest diversity was recorded for Bharamagiri Wild Life Sanctuary, with the values of H' - 3.37991 and D - 0.95834, whereas it was lowest for Ranipuram Wildlife Sanctuary with value of H' - 2.540636 and D -0.87597. The preliminary survey indicates higher diversity of orchids in natural forests, which includes rare, endangered species such as Bulbophyllum mysorense, Aerids cripa, A maculosa, Dendrobium crepidatum, Cymbidium bicolor, Rhyncostylis retusa etc. With respect to the species diversity four genera had more number of species compared to other genus, viz., Dendrobium, Bulbphyllum, Hebanaria and Oberonia and maximum number of orchid species were recorded in the genus Dendrobium followed by Bulbophyllum.
A total of 46 accessions belonging to14 genera were rescued and established in the orchidarium of which 26 were native to Central Western Ghats; 4 accessions from CoA, Padannakkad in which two accessions were tissue culture plants maintained at Department of Plant Biotechnology (one species each of Dendrobium and Phalenopsis) and 2 accessions from natural habitat of Padanakkad (one species each of Dendrobium and Acampe); 7 accessions from Sikkim (1 Vanda, 1 Coelogyne, and 5 Cymbidium) and 9 accessions were hybrids collected from Bengaluru, comprising of 6 Dendrobiums, 1 Mini Cattleya, 1 Oncidium, and 1 Phalaenopsis.
The vegetative and reproductive characters of orchids were recorded based on descriptor available from National Research Centre on Orchids, Sikkim, and were further classified based on their generic characteristics. The vegetative characters reveal variations among the species which could effectively differentiate the accessions from one another. The plant height ranged from 5.9 cm to 126 cm. The maximum plant height and number of leaves were recorded in PDK/ORP-5 (Vanda), the maximum leaf length in PDK/ORP-25 (Cymbidium) and highest number of sprouts in PDK/ORP-25 (Bulbophyllum fischeri). The reproductive characters were recorded at flowering phase for 6 accessions. The flowers were exquisite and showy which exhibit different shapes and colours, the largest flower was recorded in PDK/ORP-16 (Dendrobium hybrid 4) and the longevity of the flower ranged from 8 days (PDK/ORP-45: Acampe) to 26 days (PDK/ORP-20: Dendrobium sp. from Brahmagiri).
The molecular characterization was done to study the diversity of the selected 17 accessions belonging to the 14 genera. Out of 30 RAPD primers 10 RAPD primers were selected based on the quality and intensity of amplification. The 10 selected primers produced a total of 399 scorable DNA fragments of high polymorphism that were present among 14 orchids genera, with amplicons in the size range of 300 – 1700 bp. The dendrogram separated the 17 accessions into 6 groups, the range of similarity coefficients was from 0.08 to 0.48 in 14 genera. A total of 20 diagnostic bands were observed, in which OPA 18 produced 6 species specific bands whereas OPA 16 failed to produce any diagnostic band.
The intra generic characterization was carried for detecting polymorphism and duplicates, if any, in Vanda and Dendrobium. Nine accessions each of genera Vanda and Dendrobium were separately amplified using 5 selected primers. A total of 192 RAPD bands were produced in Vanda (size range : 150–1450 bp ) whereas 186 RAPD bands in Dendrobium (size range:175–1625 bp) . The range of similarity coefficients for the Vanda was 0.15 to 0.80, and for Dendrobium was 0.15 to 0.70 and the dendrogram separated the accessions into 3 groups each.
The Mycorrhizal association study was carried on 14 genera which were subjected to investigations for detecting mycorrhizal association in accessions. The epiphytic species were found to be more associated with mycorrhizae, as their roots are in contact with mosses and debri of organic material. The aerial roots and new roots showed infestation only when they had contact with the substrate. The hyphae and spore of mycorrhizae detected in all samples were of similar type, but they varied in the colonization percentage (60-100%).
The study revealed that, ideal period for general growth of the plants under Padanakkad condition is January-February while the sprouting was more during June. Genera like Acampe, Bulbophyllum, Coelogyne, Cymbidium, Dendrobium etc showed faster growth in the orchidarium compared to the rest. Six of the accessions flowered in the orchidarium among which one was a wild collection from Brahmagiri. It is a promising genotype which can be used for breeding purposes as it has the longest flower duration (26 days), bright colour, large petals (45.7mm) & sepals (35.6mm) and it flowered two times within 10 months. Morphological and molecular data revealed that there is no duplication in the collection, even within the same genus.