Roots of Pennisetum sp. possess the competence to generate nanoparticles of noble metals

Roots of plants have immense reducing potential. Ions of noble metals namely Au3+ and Ag+ get reduced easily to form Au and Ag nanoparticles (NPs), respectively. Therefore, we hypothesize that plant roots could have potential to form Au-NPs and Ag-NPs. For present investigations, plants of Pennisetum glaucum L. were used to evaluate if their roots possess capacity to generate metal NPs. The generation of Au-NPs and Ag-NPs was initially presumed based on colour change, and confirmed by UV-vis spectra, TEM and EDX investigations. Pale yellow Au3+ and colourless Ag+ solutions turned purple and brown, respectively, by roots of Pennisetum sp. within 8 h. Absorption spectra of respective solutions showed plasmon resonance band at 560 nm and 420 nm confirming the presence of Au-NPs and Ag-NPs. TEM coupled with SAED revealed the presence of crystalline spherical NPs in the size range of 5-50 nm in these solutions. EDX further confirmed the presence of Au and Ag as NPs of respective solutions. These results confirmed that the roots of P. glaucum possess ideal reducing strength to generate Au-NPs and Ag-NPs exogenously in the aqueous phase.

Dominance-diversity; community-coefficient and niche-width relations of woody species in Montane forests of Garhwal Himalaya; India

The synthetic characters of different plant communities are analysed. Community-coefficient for tree and shrub layer were 89.99 and 88.49; respectively in North-West aspect of Cedrus deodara forest; probably due to maximum number of species common to both sites. Among the twelve tree species; only two viz.; Cedrus deodara and Cupressus torulosa showed 100 presence amongst all the sites. The maximum equitability (10.47) value was computed in site five; because of similar type of species found in this site. Cedrus deodara (6.34) and Cupressus torulosa (5.54) had broader niches due to their presence at all the sites. Species diversity was highest (3.22) on the North West (NW) aspect of the V site and was directly related to the high density of tree species in this site. Dominance-diversity curve (d-d curve) for the tree layer and shrub layer; based on Importance Value Index (IVI) exhibited a geometric series for all forest sites except site IV; where it reflected Preston's log normal models. The log normal distribution of this site indicated the mixed nature of vegetation. These species are gradually loosing their niche width; density; dominance and diversity in different sites because of over exploitation and over grazing pressure on these species. In view of the great anthropogenic pressure on the plant community; conservation and management measures are required for sustainable use of these important ethnobotanical plant species and plant biodiversity protection