Browsing by Author "Leena Gohain"

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Antifungal activity of two alkaloids of Zephyranthes citrina and their field efficacy against powdery mildew (Erysiphe cichoracearum) of balsam
(2010) Udai P. Singh; Leena Gohain; Sudarshan Maurya; Amitabh Singh; Vidya B. Pandey; Ashok K. Singh
The anti-fungal activity of two alkaloids isolated from bulbs of Zephyranthes citrina was observed against 10 fungi, viz, Aternaria solani, A. triticina, Curvularia lunata, C. maculuns, Cercospora malvacearum, Erysiphe sp., Fusarium udum, Helminthosporium pisi, H. speciferum and Ustilago cynodontis. Different concentrations (200, 400, 600, 800, 1000 μg/ml of alkaloids (A and B) were used. Spore germination was inhibited at 600, 800, 1000 μg/ml. B alkaloid was used against Erysiphe cichoracearum causing powdery mildew in balsam (Impatiens balsamina) in the field as pre-and post-inoculation treatments at 1000, 1500, 2000 μg/ml doses. The extract was effective in both pre-and post-inoculation treatments. Foliar application of this alkaloid resulted in inducing synthesis of phenolic acid in the leaves of balsam. Maximum phenolics were detected in the leaves treated with 1500 μg/ml in both pre-and post-inoculation treatments. The increase in the production of phenolics in treated leaves of balsam can be correlated with the induction of resistance in treated plants against powdery mildew. The significant efficacy of the alkaloid under field conditions opens the possibility of its use by farmers for also controlling other diseases. © 2010 Taylor & Francis.
Foliar spray of aqueous extract of neem (azadirachta indica) cake to control balsam (Impatiens balsaminia) powdery mildew
(2010) U.P. Singh; S. Maurya; Amitabh Singh; Leena Gohain
Neem cake is used as a soil amendment. It releases nutrient into the soil very slowly. It is also an insect repellent. It improves the physical as well as biological conditions of the soil such as soil aeration, water holding capacity and also the microflora in the rhizosphere. Aqueous extract of neem cake was used against powdery mildew (Erysiphe cichoracearum) of balsam (Impatiens balsaminia) in the field at 25, 50, 75 and 100%. The efficacy was observed even at low concentrations (25%). Foliar application of aqueous extract of neem cake induced synthesis of phenolic acids in balsam. Maximum phenolic acid was detected in balsam plant leaves treated with 50% neem cake followed by 75% in both pre-and post-inoculation treatments. The induction of phenolic acid in plants was correlated with the induction of resistance in treated plants against powdery mildew. © 2010 Taylor & Francis.
Phenolic acid changes in mycelia of Sclerotium rolfsii as influenced by neem (Azadirachta indica) cake and Zephyarenthes citrina bulb
(2010) U.P. Singh; Leena Gohain; Amitabh Singh; S. Maurya; S. Sahni
High performance liquid chromatographic (HPLC) analysis of mycelia of Sclerotium rolfsii grown on neem cake, and Zephyarenthes citrina bulb incorporated media was carried out. Several phenoloic acids, e.g., gallic, tannic, caffeic, cinnamic, chlorogenic and O-coumeric acids, were found in considerable amounts in treated mycelial mat as compared to the control. The amount of phenloic acids increased with increased concentration of both the materials in mycelia of 7 and 14 day-old cultures. Due to anti-oxidant and several other properties of phenolic acids, the senescence of the fungus has been prolonged which may be one probable reason of sustaining the virulence of the pathogen. © 2010 Taylor & Francis.