Browsing by Subject "medicinal plant"
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Item Ecophysiological study of Centella asiatica (Linn.) Urban of Nepal(Department of Botany, 2011) Devkota, Anjanavii Centella asiatica (L.) Urban, commonly known as Indian Pennywort, is an important ethnomedicinal plant of tropical to subtropical region. It is a clonal perennial herb with a wide range of enthomedicinal uses such as blood purifier, memory enhancer, anticancer, antidepressive etc. Distribution pattern, abundance, life history traits, leaf nitrogen content, genetic diversity of population, and quantification of eight secondary metabolites of 21 populations of Centella asiatica from different habitats and regions of Nepal were studied. Effects of different environmental factors (moisture, soil texture, light and shading) and integrated manuring on growth traits and yield of C. asiatica were determined in pot-grown plants treated under randomized block design. Centella asiatica grows in a wide range of habitats from shady grassland, open grassland, to open agricultural land in tropical to temperate area in Nepal. In terms of density and plant biomass, partially shaded grassland was the most suitable natural habitat for C. asiatica. Density and biomass yields varied significantly with habitat types, with mean value of 72.53 pl/m 2 and 37.95 g/m 2 , respectively. The flowering peak was recorded in April-June and it little varies in different habitats. The freshly collected seeds had the highest viability which declined progressively as the duration of storage increased. Pretreatment like soaking seeds with GA 3 prior to sowing reduced the time required for initiation of germination. Seed germination of C. asiatica was affected adversely by salinity. Aqueous extract of some invasive plants viz. Chromolaena odorata, Parthenium hysterophorus, Ageratum conyzoides and Xanthium strumarium had inhibitory effects on germination, which threaten the population density of C. asiatica in nature. The pot experiment with different moisture levels (125% FWC (surplus water), 100% FWC, 70% FWC and 30% FWC) showed that the dry matter production and yield in Centella asiatica was highest in 100% FWC, followed by 70% due to higher growth characteristics such as number of primary branches, leaves, and leaf chlorophyll contents. Growth under four levels of shade (0, 30, 50 and 70%) showed that dry matter production and yield was significantly higher in 30% shade, followed by 50 %. Asiatic acid was significantly higher in 70% shading. There was no significant effect of shading on other measured secondary metabolites. Growth traits and yield of C. viii asiatica was significantly higher in sandy loam soil than clay-loam and pure sand. All measured secondary metabolites were significantly higher in sand than in clay-loam and sandy loam. The pot experiment with different integrated manuring conditions (Urea: FYM, 100:0; 75:25; 50:50; 25:75; 0:100; and control - no manure) showed higher yield and better growth traits of Centella asiatica in integrated manuring . Concentration of all secondary metabolites measured in present study was significantly higher in open agricultural land than in shady and open grasslands. Mean concentration of asiaticoside, the most important bioactive component of C. asiatica, was 1.8% (dw). Concentration of secondary metabolites was higher in samples from central Nepal than western and eastern Nepal. Asiaticoside content was inversely related with the altitude of samples collected. Asiaticoside content was higher in samples collected from 150600 m asl. Thus, a negative correlation was observed between altitude and asiaticoside content while the opposite was for quercetin-3-O- glucuronide content. Concentration of secondary metabolites was higher in wild than in transplanted samples. Essential oil yield of Centella asiatica from different habitats ranged from 0.10 (open grassland) to 0.12% (shady grassland). Total yield of essential oil was higher in samples from partially shaded habitat, but concentration of major components was higher in open agricultural land. Genetic diversity study of 21 different populations of Centella asiatica was carried out by morphological and molecular marker (RAPD). Morphological characters were significantly different among 21 populations. Two distinct morpho-types of Centella asiatica were clearly distinguished in dendrogram based on morphology; one with small leaves, dentate to serrate margin, and creeping form, and the other with large leaves, crenate to entire margin, and erect form. Molecular marker data showed similarity coefficient from 0.52-0.91 among the population indicating a moderate diversity of C. asiatica in Nepal. In conclusion, morphology, genetic character and active phytochemicals in Centella asiatica at different habitats and ecological regions of Nepal varied. Transplanted samples had lower amount of secondary metabolites than in wild samples. Key Words:Item Growth Strategy and Population Structure in a Threatened Herb (Neopicrorhiza scrophulariiflora) in Alpine Himalaya(Department of Botany, 2009) Devkota, BalakVariation in growth strategy, plant performance and population structure was studied in a threatened longlived clonal medicinal herb [(Neopicrorhiza scrophulariiflora (Pennell) .Y. Hong)] in relation to altitude and other environmental variables. Seven populations were selected from lower alpine and upper alpine habitats in Walangchung Gola and Ghunsa sectors within Kangchenjunga Conservation Area, East Nepal.The two sectors differ in terms of degree of protection at landscape level (Ghunsa sector being more protected than Walangchung Gola sector) and level of precipitation (higher precipitation in Ghunsa sector). The habitat of N. scrophulariiflora ranged from shrubland to open rocky/scree or grassy slopes on increasing altitude. There were strong geographical (sectorial) and altitudinal differences in the relative contribution of sexual and vegetative growth strategies in population persistence. Altitude was also related to the inter-population variation in other plant performance traits as well as in population size and structure.Sexual allocation and sexual reproductive effort were high in lower alpine populations. As compared to Ghunsa sector (moist sites); populations from alangchung Gola sector (drier sites) produced large-sized genets (except in highly disturbed site). hunsa populations on the other hand showed significantly Variation in growth strategy, plant performance and population structure was studied in a threatened longlived clonal medicinal herb [(Neopicrorhiza scrophulariiflora (Pennell) D.Y. Hong)] in relation to altitude and other environmental variables. Seven populations were selected from lower alpine and upper alpine habitats in Walangchung Gola and Ghunsa sectors within Kangchenjunga Conservation Area, East Nepal. The two sectors differ in terms of degree of protection at landscape level (Ghunsa sector being more protected than Walangchung Gola sector) and level of precipitation (higher precipitation in Ghunsa sector). The habitat of N. scrophulariiflora ranged from shrubland to open rocky/scree or grassy slopes on increasing altitude. There were strong geographical (sectorial) and altitudinal differences in the relative contribution of sexual and vegetative growth strategies in population persistence. Altitude was also related to the inter-population variation in other plant performance traits as well as in population size and structure. Sexual allocation and sexual reproductive effort were high in lower alpine populations. As compared to Ghunsa sector (moist sites); populations from Walangchung Gola sector (drier sites) produced large-sized genets (except in highly disturbed site). Ghunsa populations on the other hand showed significantly large number of flowering ramets per genet than did by Walangchung Gola populations. This shows that at high altitudes and at drier sites, plants tend to invest less in sexual fecundity and more in traits ensuring persistence of vegetative offshoots. Populations from Walangchung Gola sector showed higher proportions of juvenile and vegetative adult ramets, with poor representation of very young and reproductive adult ramets. In highly disturbed populations, proportion of reproductive adult was even greatly reduced. On the other hand, populations from Ghunsa sector showed almost equal proportions of young, juvenile and vegetative adult ramets. Proportion of adult reproductive ramets was also significantly high in Ghunsa populations than in Walangchung Gola populations. This showed that Ghunsa populations were stable in density and self-replacing. The strong relationship between environmental conditions and plant growth strategy, adult performance and population structure of N. scrophulariiflora has important implications for its in situ management. The lower performance of plants (in terms of growth-related traits), and low sexual reproductive efforts in higher alpine sites (especially Walangchung Gola sector) indicate that these populations need immediate action to protect them from illegal and premature harvesting. In such populations management should focus on increasing seedling recruitment and reducing damage to the reproductive adults. Thus long-term plan with a strong measure for sustainable utilization system is needed to manage the target species populations simultaneously respecting traditional access rights of the local users. Extremely low seedling recruitment makes this species highly vulnerable if harvesting is applied at fairly higher level, because in such condition population genetic diversity can be expected to be very low. Thus applying low level of harvesting with fairly long rotation is a good strategy for population persistence. Level of harvesting should be even low in harsh higher alpine habitats of Walangchung Gola sector. Key words: altitude, disturbance, medicinal plant, plant performance, soil variable, sustainable management. large number of flowering ramets per genet than did by Walangchung Gola populations. This shows that at high altitudes and at drier sites, plants tend to invest less in sexual fecundity and more in traits ensuring persistence of vegetative offshoots. Populations from Walangchung Gola sector showed higher proportions of juvenile and vegetative adult ramets, with poor representation of very young and reproductive adult ramets. In highly disturbed populations, proportion of reproductive adult was even greatly reduced. On the other hand, populations from Ghunsa sector showed almost equal proportions of young, juvenile and vegetative adult ramets. Proportion of adult reproductive ramets was also significantly high in Ghunsa populations than in Walangchung Gola populations. This showed that Ghunsa populations were stable in density and self-replacing. The strong relationship between environmental conditions and plant growth strategy, adult performance and population structure of N. scrophulariiflora has important implications for its in situ management. The lower performance of plants (in terms of growth-related traits), and low sexual reproductive efforts in higher alpine sites (especially Walangchung Gola sector) indicate that these populations need immediate action to protect them from illegal and premature harvesting. In such populations management should focus on increasing seedling recruitment and reducing damage to the reproductive adults. Thus long-term plan with a strong measure for sustainable utilization system is needed to manage the target species populations simultaneously respecting traditional access rights of the local users. Extremely low seedling recruitment makes this species highly vulnerable if harvesting is applied at fairly higher level, because in such condition population genetic diversity can be expected to be very low. Thus applying low level of harvesting with fairly long rotation is a good strategy for population persistence. Level of harvesting should be even low in harsh higher alpine habitats of Walangchung Gola sector. Key words:, disturbance, medicinal plant, plant performance, soil variable, sustainable management.