Studies in vitro seed germination and morphogenesis in orchids

Abstract

Most of the orchid species are cross pollinated viability and storage of pollen seeds and protocorms for getting desired hybrids were investigated. The pollen viability of Spethoglottis plicate Epidenrumradicans and Dendrobium “Jaquelyn Thomas” was reduced when stored with a dehydrant (silicagel). Storage at low temperature (4 °C) enhanced pollen viability compared to that at room temperature in all the three species. Seed viability of these three species was enhanced when stored with dehydrant. Protocorn regeneration of Dendrobium “Jaquelyn Thomas” was better when stored with glycerol 10% as a cryoprotectant. Among three media used, S.plicata seeds germinated successfully in Pundson’s medium in a short time. Seed germination of E. radicans and Dendrobium “Jaquelyn Thomas” was better in MS medium. Seed germination of all three species was faster with NAA, GA and BA at 0.1 mg l-1 and 1 mg l-1 as compared to control. Among the three growth regulators, GA at 1 mg l-1 was best as the time required for germination was half that required with control. The percent seed germination in all three species was higher with NAA, GA and BA at 0.1 mg l-1 as compared to other treatments. Growth of the seeding was enhanced with growth regulators either alone or in combination than control in all the three species. Less time was required for complete growth of the seedling with IBA+GA+BA each at 5 mg l-1 compared to other treatments. Histochemical and ultra structural studies revealed the utilization of metabolites for organal development. Lipids, proteins and carbohydrates were utilized in the order mentioned during seed germination.