Habitat analysis and domestication studies on orilathamara (Nervilia aragoana Gaud)

Abstract

The present investigations on “Habitat analysis and domestication studies on ‘Orilathamara’ (Nervilia aragoana Gaud.)” was carried out at the Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara during 2009 – 2011, with the objectives to collect the source plants of the drug Orilathamara from wild, to carry out detailed natural habitat analysis and to analyze the response of the species to domestication.

The study was conducted in four separate experiments as exploration and collection of source plants of Orilathamara from forest, natural habitat analysis, domestication trial and biochemical studies.

Forest explorations were carried out in the Peechi – Vazhani wild life sanctuary. Information regarding the occurrence of the plant was collected from tribal herb gatherers, voucher specimens collected and herbarium made. Four species of Nervilia were identified from Peechi forests. They were Nervilia infundibulifolia (Blatt. & McCann), Nervilia plicata (Andr.), Nervilia crociformis (Zoll. & Moritzi) and Nervilia aragoana Gaud. All the four species were categorised as endangered.

Natural habitat studies were also carried out in the Peechi forests. It was mainly confined to Nervilia aragoana, the only species available in sufficient numbers. Complete life cycle of the plant was studied in the natural habitat. The habitat characteristics indicated that Nervilia aragoana is a delicate orchid found in the ground vegetation of moist deciduous forest. Physical properties including soil aggregate analysis and chemical properties of the forest soil were analysed and results presented.

Domestication trial was carried out in the field attached to the Department. There were two shade levels (50%, 25%) and four growing media as FYM + sand + soil (1:1:1), leaf compost + sand + soil (1:1:1), coir pith compost + sand + soil (1:1:1) and vermi compost + sand + soil (1:1:1).

All the growing media were analysed for their physical properties, aggregate stability and chemical properties and results presented.

From the study it was observed that there was no significant difference in sprouting percentage, days to leaf emergence, complete unfurling of leaves and total biomass production of Nervilia aragoana under different treatments. Significant differences were observed in growth parameters like petiole length, leaf length, leaf width and leaf area and also tuber yield per plot. For all these parameters, performance was better under 50% shade level and in the growing medium containing FYM, sand and soil in equal proportions. Tuberization and tuber development of the species was also documented during the study and the same was correlated with weather data during the period.

Biochemical analysis was also carried out to estimate the constituents like chlorophyll, starch, soluble sugars, protein, amino acids and soxhlet extractables. Both the wild and domestic samples were analysed. The results indicated that constituents like sugars, protein and amino acids were higher in domestic tubers and starch was higher in wild tubers. TLC profile of sugars and amino acids revealed the presence of seven sugars and five amino acids in Nervilia aragoana. Anatomical study of the tuber was carried out which revealed the presence of starch grains, Calcium oxalate crystals and mycorrhizal associations in the ground tissue. In short, the study identified four species of Nervilia in Peechi forests and they were categorised as endangered. Natural habitat characteristics of the species have been described and complete life cycle documented. Domestication proved to be successful in Nervilia aragoana. 50% shade level and normal potting mixture containing FYM, sand and soil proved to be the ideal one for growth and tuber production. Domestication also did not affect the quality of the drug in respect of components studied.