studding arvane-bezghi (hymenocrater platystegius rech.f.) different ecotypes at natural habitat in khorasan razavi province: principal component analysis

introduction hymenocrater from lamiaceae family is a perennial bush with 24 species in the world and 10 different species in natural habitats of iran (satil et al., 2007). hymenocrater platystegius rech. is exclusive to khorasan province in the north east of iran (mozaffarian, 1996). according to available information, %5 of plant species of iran are becoming extinct, which is 550 times higher than the forecast of the international :union: for conservation of nature and natural resources. hymenocrater is an important genius of lamiaceae family. hymenocrater belongs to stachyioideae subfamily and have numerous varieties which are expanded from iran to iraq, pakistan and afghanistan. this genius has aromatic essential oil and antimicrobial effects. some researchers has shown different characteristics of its oil components are related to the differences in geographical conditions and habitats of the collecting regions. moreover, proper management and optimal utilization of natural ecosystems requires sufficient scientific knowledge and understanding. therefore, domestication and cultivating domestic plant cultivation can reduce harvest pressure on natural areas for rare, slow grower and critically endangered species (vogel, 2004). in recent years, lower precipitation and land use changes threatened this species seriously. the purpose of this study was to evaluate ecological characteristics of this species, their natural habitat and to evaluate possibilities for domestication in field condition. the aim of this study was to select the best habitats of hymenocrater platystegius rech. based on ecological and morphological characteristics of species in the natural habitats. materials and methods this experiment was performed during 3 years (2008-2010). for this purpose, 6 habitants (bezd, bezgh, bazangan, golmakan, kalat and zoshk) in khorasan province of iran were chosen and all plant criteria, including morphological characteristics (plant height, crown diameter, stem, flower, leaf dry weight to shoot dry weight, number of seeds, plant density, fresh weight and dry weight) and environmental requirements in the natural habitats (annual precipitation average, annual temperature average, relative humidity, climate condition, topographical features (altitude and slope) were investigated. golmakan area was determined as the base station data for evaluating and recording the phenological stages, because it had a higher plant density and diversity of topographic features. then, collected data was analyzed using pca and ca methods. results and discussion in this study, the effects of environmental conditions on morphological and ecological characteristics of hymenocerater platystegius rech. were observed. results showed that the natural habitats in the area were highly similar and 4 ecotypes were recognized there. among 15 plant criteria investigated the leaf dry matter, number of stem per plant, number of nod per stems and the nodes bearing flower contributed to 97% of the variance. topography and climate analyses showed that climate was the most important factor with +0.55 loading which had the highest impact on the main component. in general, 5 habitats were recognized with 70% similarity in topography and climatic conditions. conclusion finally, both golmakan and kalat were in one group (had closed similarity in environmental conditions including topography, precipitation, soil texture, elevation, aspects and other habitats were in 5 separate places. these results showed that the environmental factors had more effect on morphological characteristics of this species. therefore, considering the destruction of natural habitats and extinction conditions for this species, it should have a period proportional to the regeneration period, such as grazing for conservation. as climate change has huge effects on endemic species then domestication could be the best way for their protection and conservation.