Crop-ecology and nutritional variability influence growth and secondary metabolites of Stevia rebaudiana Bertoni.

BACKGROUND: Plant nutrition and climatic conditions play important roles on the growth and secondary metabolites of stevia (Stevia rebaudiana Bertoni); however, the nutritional dose is strongly governed by the soil properties and climatic conditions of the growing region. In northern India, the interactive effects of crop ecology and plant nutrition on yield and secondary metabolites of stevia are not yet properly understood. Thus, a field experiment comprising three levels of nitrogen, two levels of phosphorus and three levels of potassium was conducted at three locations to ascertain whether the spatial and nutritional variability would dominate the leaf yield and secondary metabolites profile of stevia. RESULTS: Principal component analysis (PCA) indicates that the applications of 90 kg N, 40 kg P2O5 and 40 kg K2O ha-1 are the best nutritional conditions in terms of dry leaf yield for CSIR-IHBT (Council of Scientific and Industrial Research- Institute Himalayan Bioresource Technology) and RHRS (Regional Horticultural Research Station) conditions. The spatial variability also exerted considerable effect on the leaf yield and stevioside content in leaves. Among the three locations, CSIR-IHBT was found most suitable in case of dry leaf yield and secondary metabolites accumulation in leaves. CONCLUSIONS: The results suggest that dry leaf yield and accumulation of stevioside are controlled by the environmental factors and agronomic management; however, the accumulation of rebaudioside-A (Reb-A) is not much influenced by these two factors. Thus, leaf yield and secondary metabolite profiles of stevia can be improved through the selection of appropriate growing locations and proper nutrient management.

Selective Th2 Upregulation by Crocus sativus: A Neutraceutical Spice.

The immunomodulatory activity of an Indian neutraceutical spice, saffron (Crocus sativus) was studied on Th(1) and Th(2) limbs of the immune system. Oral administration of alcoholic extract of Crocus sativus (ACS) at graded dose levels from 1.56-50 mg/kg p.o. potentiated the Th(2) response of humoral immunity causing the significant increases in agglutinating antibody titre in mice at a dose of 6.25 mg/kg and an elevation of CD19(+) B cells and IL-4 cytokine, a signature cytokine of Th(2) pathway. Appreciable elevation in levels of IgG-1 and IgM antibodies of the primary and secondary immune response was observed. However, ACS showed no appreciable expression of the Th(1) cytokines IL-2 (growth factor for CD4(+) T cells) and IFN-γ (signature cytokine of Th(1) response). A significant modulation of immune reactivity was observed in all the animal models used. This paper represents the selective upregulation of the Th(2) response of the test material and suggests its use for subsequent selective Th(2) immunomodulation.

Organic acid production and plant growth promotion as a function of phosphate solubilization by Acinetobacter rhizosphaerae strain BIHB 723 isolated from the cold deserts of the trans-Himalayas.

An efficient phosphate-solubilizing plant growth-promoting Acinetobacter rhizosphaerae strain BIHB 723 exhibited significantly higher solubilization of tricalcium phosphate (TCP) than Udaipur rock phosphate (URP), Mussoorie rock phosphate (MRP) and North Carolina rock phosphate (NCRP). Qualitative and quantitative differences were discerned in the gluconic, oxalic, 2-keto gluconic, lactic, malic and formic acids during the solubilization of various inorganic phosphates by the strain. Gluconic acid was the main organic acid produced during phosphate solubilization. Formic acid production was restricted to TCP solubilization and oxalic acid production to the solubilization of MRP, URP and NCRP. A significant increase in plant height, shoot fresh weight, shoot dry weight, root length, root dry weight, and root, shoot and soil phosphorus (P) contents was recorded with the inoculated treatments over the uninoculated NP(0)K or NP(TCP)K treatments. Plant growth promotion as a function of phosphate solubilization suggested that the use of bacterial strain would be a beneficial addition to the agriculture practices in TCP-rich soils in reducing the application of phosphatic fertilizers.

Effect of decapitation and nutrient applications on shoot branching, yield, and accumulation of secondary metabolites in leaves of Stevia rebaudiana Bertoni.

The axillary buds of stevia (Stevia rebaudiana Bertoni) often remain dormant for a long time and sometimes remain dormant permanently until the plants enter into the reproductive stage. The present study was conducted to ascertain whether decapitation and foliar fertilization enhance the productivity and quality of stevia through breaking the apical dominance and increasing physiological activities. Ten treatment combinations comprising two cultural operations (non-decapitation and decapitation) and five foliar spray treatments (water spray control, KNO3 @ 5.0gL(-1), Ca(NO3)2 @ 4.06gL(-1), CuSO4·5H2O 2.0gL(-1) and (NH4)6Mo7O24 @ 1.0gL(-1)) were applied. The decapitation of apical buds of stevia increased the branches and increased dry leaf yield by 13 and 17% compared with non-decapitation during 2010 and 2011, respectively, without affecting quality. Foliar application of nutrient solutions also exerted a considerable effect on growth parameters, yield attributes and chlorophyll content, and significantly (P=0.05) higher dry leaf yield ranging from 8 to 26% over the control. Among the foliar spray treatments, KNO3 @ 5.0gL(-1) and Ca (NO3)2 4.06gL(-1) were found most effective in dry leaf yield. Thus, the decapitation of apical buds and foliar application of KNO3 and Ca (NO3)2 could enhance the productivity of stevia through improving the growth of axillary buds and physiological activities.

Evaluation of Antioxidant Activity of Picrorhiza kurroa (Leaves) Extracts.

Picrorhiza kurroa is a well-known herb in Ayurvedic medicine. Although it shows antioxidant, antiinflammatory and immunomodulatory activities, it is most valued for its hepatoprotective effect. The rhizomes are widely used against indigestion problems since ancient times due to improper digestive secretions. Aim of this study was to explore antioxidant study of P. kurroa leaves for a new source of naturally occurring antioxidants. Two pure compounds, luteolin-5-O-glucopyranoside (1) and picein (2) were isolated from butanol extract through column chromatography. Different extracts of P. kurroa leaves (ethanol, ethyl acetate, butanol) were quantified for isolated compound (2) by high-performance liquid chromatography. All the extracts and isolated compounds were evaluated for its antioxidant activity using two assays, 2,2-diphenyl-1-picrylhydrazyl radical and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) assay. The linear detection range was 1.56-200 µg/ml for picein. The limit of detection and limit of quantification for picein were 2.34 and 7.81 µg/ml, respectively. Butanol and ethyl acetate extract showed greater antioxidant activity as compare to ethanol extract. Compound 1 and ascorbic acid showed nearly similar antioxidant activity where as 2 showed no activity at standard concentration. The IC50 values for 2,2-diphenyl-1-picrylhydrazyl radical and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) assay for ascorbic acid, compound 1, ethanol extract and its different fractions (ethyl acetate and butanol) were found to be 0.81, 1.04, 67.48, 39.58, 37.12 and 2.59, 4.02, 48.36, 33.24, 29.48 µg, respectively.

Chemical composition of hydrodistilled and solvent volatiles extracted from woodchips of Himalayan Cedrus: Cedrus deodara (Roxb.) Loud.

The essential oil and extract obtained from the wood chips of Cedrus deodara by hydrodistillation and percolation respectively have been analyzed by GC-FID and GC-MS techniques. Thirty four compounds were identified from the essential oil and twenty six from the extract accounting for 98.3 and 94.6% respectively of total identifications. While the major components of the oil were beta-himachalene (38.3%), alpha-himachalene (17.1%) and gamma-himachalene (12.6%), those of the extracts were E-gamma-atlantone (38.5%) and E-alpha-atlantone (10.2%).