Sitansu Pan ¹, Someshwar Bhagat ²

Affiliations
1 Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal - 741252, IN
2 Division of Field Crops, Central Agricultural Research Institute, Port Blair, Andaman-744101, IN

Abstract

Ten isolates of Trichoderma spp. isolated from rhizosphere of different crops were evaluated for their antagonistic potential against five soil borne plant pathogens, viz., Rliizoctonia solani, Fusarium oxysporum f sp radicis-lycopersici, Macrophomina phaseolina and Sclerotium rolfsii using dual culture technique and production of volatile and non-volatile antibiotics. Sclerotial antagonism by the biocontrol strains was tested with R. solani and S. rolfsii. The isolate T₂, T₄ and T₇ against ^Pythium sp., T₁, T₇ and T₁₀ against F. oxysporum f. sp radicislycopersici, T₃ and T₉ against R. solani, T₇ against S. rolfsii and T₆ against M. phaseolina were the most efficient. The highest percentage inhibition of respective pathogen through the production of certain metabolites of Trichoderma isolates was recorded with T₇ against Pythium sp, and Fusarium oxysporum sp. radicis-lycopersici, T₁ against R. solani, T₅ and T₆ against S. rolfsii and T₉ isolate against M. phaseolina. Trichoderma isolate T₉ and T₂ were most effective in inhibition of sclerotia formation, production and germination of sclerotia of R. solani and S. rolfsii, respectively.

Keywords

Antagonistic Potential, Sclerotial Antagonism, Trichoderma Spp., Volatile And Nonvolatile Metabolites.

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Someshwar Bhagat ¹, Sitansu Pan ²

Affiliations
1 Division of Field Crops, Central Agricultural Research Institute, Port Blair- 744101, Andaman & Nicobar Islands, IN
2 Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia - 741252, West Bengal, IN

Abstract

Ten isolates of Trichoderma spp. isolated from rhizosphere region Of different crops were evaluated for their ability to produce extracellular hydrolytic enzymes, viz., β-1, 3 glucanase, chitinase and cellulase enzymes with different concentrations ef carbon sources, pM, and temperature levels and the induction of systemic resistance in gram seedlings. Highest chitinase and β-1, 3 glucanase activity were observed in TR₂ isolate whereas TH₂ isolate exhibited highest activity of cellulase. TH₁ and TH₅ were the next best isolates in their chtinase enzyme activity. Similarly, TR₁ and TH₁ isolates followed the TR₂ for β-1, 3-glucanase activity. The activity of cellulase was highest in TH₂ isolate followed by TH₅ and TR₂, which were statistically significant. The enzyme β-1,3 glucanase was produce in media with pH 4.0 to 8.0 with an optimum pH5.5. The optimum pH for chitinase and cellulase enzyme activity was recorded at 5.0. With the variable temperatures, i.e., 20, 25, 30, 35 and 40°C, the enzyme activities of all three enzymes showed highest at 30°C. The activities of enzymes β-1,3 glucanase and chitinase was recorded highest at 3.0 and 4.0% concentrations of glucan and chitin, respectively whereat 0.75% concentration of cellulose showed highest cellulase activity. The highest induced resistance by Trichoderma isolates in gram seedlings, was recorded by TR₁, through the increase activity of PAL and β-1,3 glucanase and TH₁ by enhance activity of peroxidase enzyme.

Keywords

β,-1,3 Glucanase, Cellulase, Chi Tinase, Induced ResistanceTrichodermaspp.

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Someshwar Bhagat ¹, Sitansu Pan ¹

Affiliations
1 Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, 741252, West Bengal, IN

Abstract

The study on the management of collar rot of cauliflower, caused by Rhizoctoniu solani by a talc-based formulation of Trichoderma harzianum, was carried out during the early rabi seasons of 2005-06 and 2006-07 under field condition at Mohanpur, West Bengal with isolates of T. harzinum. The seedling dip and soil application of T. harzianum (talc-based) @ 200g per plot significantly reduced the disease incidence (63.6%) at 50 DAT followed by pre-transplanting seedling tip in T. harzianum spore suspension @ 5g/l combined with soil application of talc formulation @ 100g/plot (52.7%) and soil application of the talc formulation of T. Iiarzianum at 200g/plot (50.9%) treatment and there was corresponding yield increase in the respective treatments. The highest population density of T. harzianum was recorded in the plot treated with seedling tip and soil application (210 cfu/g soil) and the lowest in the control plot (7.5 cfu/g soil).

Keywords

Biological Management, Cauliflower, Root and Collar Rot, Talc-Based Formulation T. harzianum.

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D. K. Saha ¹, Sitansu Pan ¹

Affiliations
1 Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya Mohanpur, Nadia 741 252, West Bengal, IN

Abstract

Ability of Gliocladium virens Miller, Giddens and Foster to colonise groundnut stem pieces used as organic bait in soil was studied under varying conditions like inoculum density, soil pH, soil moisture and temperature. High temperature (40°C) was lethal for the saprophytic activities of the antagonist as colonisation of the bait was completely inhibited. In air dry soil (ca. 6.0% mhc) colonisation of bait was low (ca. 5.0 - 8.0 %) particularly at lower temperature (20°C) and low level of inoculum (20 mg/100 g soil). Acid soil (pH 5.6) at 50% soil moisture and 30°C temperature gave maximum colonisation of bait. Per cent colonisation of bait was less at either side of this temperature moisture optima.

Keywords

Antagonist, Competitive Colonisation, Gliocladium virens, Inoculum, Organic Bait.

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D. K. Saha ¹, Sitansu Pan ¹

Affiliations
1 Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal 741252, IN

Abstract

Phialospores of four isolates of Gliocladium virens viz., 15GV₁, 26GV₁, 1AGV₂ and IAGV₆ responded differentially to soil fungistasis in different soils of West Bengal according to the properties of soils explored. The pH of soil appeared to be the cardinal factor. The effect of soil fungistasis was more pronounced in alkaline soil followed by neutral soil but gradually decreased due to reduction of soil pH to acidic level. Fungistasis was more in unsterilized soil compared to sterilised one.

Keywords

Gliocladium virens, Phialospore, Fungistasis, Soil pH, Soil Type.

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D. K. Saha ¹, Sitansu Pan ¹

Affiliations
1 Department of Plant Pathology, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal, Pin-741 252, IN

Abstract

Formulation and application methods are often of paramount importance in biological control (Papavizas and Lumsden, 1980; Papavizas and Lewis, 1983; Papavizas et al .. 1984). Accordingly several techniques viz, antagonist in liquid (Kerr, 1980), organic matter (Wells et al., 1972), as seed treatment (Harmen et al., 1980; Windel, 1981; Fravel et al., 1985) and in vermiculite or in clay such as pyrax (Fravel et al., 1983) have been tested.

Keywords

Gliocladium virens, Formulation, Sodium Alginate Prill, Shelf Life.

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