Efficacy of Jatropha, Annona and Parthenium biowash on Sclerotium rolfsii, Fusarium oxysporum f. sp. ciceri and Macrophomina phaseolina, pathogens of chickpea and sorghum

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. phaseolina between 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 activeingredients 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

Evaluation of bacteria isolated from rice rhizosphere for biological control of charcoal rot of sorghum caused by Macrophomina phaseolina (Tassi) Goid

Abstract A total of 360 bacteria, isolated from the rhizospheres of a system of rice intensification (SRI) fields, were characterized for the production of siderophore, fluorescence, indole acetic acid (IAA), hydrocyanic acid (HCN) and solubilization of phosphorus. Of them, seven most promising isolates and -360) were screened for their antagonistic potential against Macrophomina phaseolina (causes charcoal rot in sorghum) by dual culture assay, blotter paper assay and in greenhouse. All the seven isolates inhibited M. phaseolina in dual culture assay, whereas six isolates solubilized phosphorous (except SRI-360), all seven produced siderophore, four produced fluorescence (except SRI-178, -229 and -305), six produced IAA (except SRI-305) and five produced HCN (except SRI-158 and -305). In the blotter paper assay, no charcoal rot infection was observed in SRI-156-treated sorghum roots, indicating complete inhibition of the pathogen, while the roots treated with the other isolates showed 49−76% lesser charcoal rot infection compared to the control. In the antifungal activity test (in green house on sorghum), all the isolates increased shoot dry mass by 15−23% and root dry mass by 15−20% (except SRI-158 and -360), over the control. In order to confirm the plant growthpromoting (PGP) traits of the isolates, the green house experiment was repeated but, in the absence of M. phaseolina. The results further confirmed the PGP traits of the isolates as evidenced by increases in shoot and root dry mass, 22−100% and 5−20%, respectively, over the control. The sequences of 16S rDNA gene of the isolates were matched with Pseudomonas plecoglossicida, Brevibacterium antiquum, Bacillus altitudinis, Enterobacter ludwigii, E. ludwigii, Acinetobacter tandoii and P. monteilii, respectively in BLAST analysis. This study indicates that the selected bacterial isolates have the potential for PGP and control of charcoal rot disease in sorghum.

K and Rupela : Evaluation of actinomycete isolates obtained from herbal vermicompost for the biological control of Fusarium wilt of chickpea. International crop research institute for semiarid tropics (ICRISAT),

ABSTRACT A total of 137 actinomycetes cultures, isolated from 25 different herbal vermicomposts, were characterized for their antagonistic potential against Fusarium oxysporum f. sp. ciceri (FOC) by dual-culture assay. Of the isolates, five most promising FOC antagonistic isolates were characterized for the production of siderophore, cellulase, protease, hydrocyanic acid (HCN), indole acetic acid (IAA) and antagonistic potential against Rhizoctonia bataticola, which causes dry root rot in chickpea (three strains viz. RB-6, RB-24 and RB-115) and sorghum (one strain). All of the five FOC antagonistic isolates produced siderophore and HCN, four of them (except KAI-90) produced IAA, KAI-32 and KAI-90 produced cellulase and CAI-24 and CAI-127 produced protease. In the dual-culture assay, three of the isolates, CAI-24, KAI-32 and KAI-90, also inhibited all three strains of R. bataticola in chickpea, while two of them (KAI-32 and KAI-90) inhibited the lonely strain in sorghum. When the FOC antagonistic isolates were evaluated further for their antagonistic potential in the greenhouse and wilt-sick field conditions on chickpea, 45-76% and 4-19% reduction of disease incidence were observed, respectively compared to the control. The sequences of 16S rDNA gene of the isolates CAI-24, CAI-121, CAI-127, KAI-32 and KAI-90 were matched with Streptomyces tsusimaensis, S. caviscabies, S. setonii, S. africanus and an identified species of Streptomyces, respectively using the BLAST searching. This study indicated that the selected actinomycete isolates have the potential for biological control of Fusarium wilt disease in chickpea