Abstract
The demand for products and technologies based on plants to control plant pathogens has increased in recent years due to concern about the use of hazardous pesticides. In the present investigation, washings of vermicompost (called biowash) prepared from foliage of Jatropha (Jatropha curcas), Annona (Annona squamosa) and Parthenium (Parthenium hysterophorus) were evaluated against fungal pathogens viz. Fusarium oxysporum f. sp. ciceri (FOC; causes wilt in chickpea), Sclerotium rolfsii (causes collar rot in chickpea) and Macrophomina phaseolina (causes charcoal rot in sorghum). Crude biowash of the botanicals were partitioned against ethyl acetate and the resultant organic and aqueous fractions were tested against the fungi. Similarly, crude biowash was also passed through C18 solid phase extraction cartridges and the resultant adsorbed and non-adsorbed fractions were tested against the fungi. Organic fractions of all the three biowash at 0.5% inhibited the growth of S. rolfsii between 78 and 87%, M. phaseolina between 62 and 65%, whereas only Parthenium was able to effectively inhibit FOC (91%), compared to control. Adsorbed fractions of all the three biowash at 0.5% inhibited the growth of S. rolfsii between 81 and 92%, M. phaseolinabetween 76 and 77% and FOC between 26 and 49%, compared to control. Both aqueous and non-adsorbed fractions of all the three biowash did not inhibit any of the fungi. Since Jatropha biowash showed consistently higher levels of inhibition (>80%) in both fractionation methods on S. rolfsii, this was selected for further purification of their secondary metabolites. When the organic fraction of Jatropha biowash was further fractionated by C18 open column chromatography with eluent 5, 10, 20, 40, 60, 80 and 100% MeOH fractions, only 80% methanol (MeOH) fraction was found to inhibit S. rolfsii. The active 80% MeOH fraction showed three clear bands when chromatographed on Silica Gel 60 F254 thin layer chromatography (TLC) plates with Rf values 0.95, 0.90 and 0.70. Hence, it was concluded that one of these three bands could be the active ingredients that inhibited S. rolfsii and can be further exploited as a bio-fungicide. Key words: Botanicals, jatropha, annona, parthenium, biowash, Sclerotium rolfsii,Fusarium oxysporum f. sp. ciceri, Macrophomina phaseolina, secondary metabolites.
Highlights
Fusarium wilt and collar rot of chickpea, caused by Fusarium oxysporum f. sp. ciceri (FOC) and Sclerotium rolfsii Sacc., respectively and charcoal rot of sorghum caused by Macrophomina phaseolina, are the three major soil and seed borne diseases of chickpea and sorghum prevalent in most chickpea and sorghum growing countries (Gopalakrishnan et al, 2005; ICRISAT, 1978 and 1991)
Washings of vermicompost prepared from foliage of Jatropha (Jatropha curcas), Annona (Annona squamosa) and Parthenium (Parthenium hysterophorus) were evaluated against fungal pathogens viz. Fusarium oxysporum f. sp. ciceri (FOC; causes wilt in chickpea), Sclerotium rolfsii and Macrophomina phaseolina
Organic fractions of Parthenium, Jatropha and Annona biowash at 0.5% inhibited the growth of M. phaseolina by 62, 62 and 65%, respectively and S. rolfsii by 85, 87 and 78%, respectively, compared to that of the control (Figures 1 and 3)
Summary
Fusarium wilt and collar rot of chickpea, caused by Fusarium oxysporum f. sp. ciceri (FOC) and Sclerotium rolfsii Sacc., respectively and charcoal rot of sorghum caused by Macrophomina phaseolina, are the three major soil and seed borne diseases of chickpea and sorghum prevalent in most chickpea and sorghum growing countries (Gopalakrishnan et al, 2005; ICRISAT, 1978 and 1991). It has been possible to manage these diseases by use of chemicals, with the increasing concern over environmental pollution by pesticides, major efforts are being made to develop environment friendly methods of plant disease control. These include use of antagonist or competitor populations of a third organism and botanicals to suppress a pathogen population, making it less abundant and less damaging than it would be otherwise. Compounds derived from such plants in general, possess no mammalian toxicity and should be exploited for controlling pathogens and insect pests of agriculturally important crops
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
