Paradigm of demographic stochasticity-Way to extinction of Valeriana jatamansi Jones, a valuable Medicinal plant in North Eastern Himalayan Region

摘要

Valeriana jatamansi Jones a newly introduced medicinal plant from Himachal Pradesh to Kalimpong, north eastern Himalayan region was conserved in the field gene banks of Kalimpong, Regional Research Station for its highly active medicinal properties and endangered listed category of the IUCN list of plants. Morphological characterization and selection of this plant was done in the field gene banks maintained at regional research stations for developing lines and ultimately releasing of composite varieties. Three types of plant phenotype having entire, sinuate and wavy type of leaf margin was observed in the heterogeneous population maintained at field gene bank in Regional Research station. Demographic stochasticity was observed in the population ofthree morphotypes where sinuate leaf blade plants was found to be lowest among other two types (below fifty in number) in the same environmental condition in this conservation. According to well known paradigm of demographic stochasticity, it is one of the probable causes of extinction of endangered individuals less than the size of 100 individuals in any region of the world. Demographic stochasticity along with allelic effect factors which itself is positive density dependence on growth rate of the plant was found extremely low which is alarming from conservation point of view.