In-vitro evaluation of natural farming inputs against Macrophomina phaseolina causing dry root rot of Chickpea

Résumé fourni par la source

Dry root rot caused by Macrophomina phaseolina is an important soil-borne disease of chickpea, particularly under warm and moisture-deficit conditions. The present investigation was undertaken to study the symptomatology, isolation, identification and pathogenicity of M. phaseolina and to evaluate natural farming inputs, in-vitro using sick soil method for its management and poisoned food technique. Diseased chickpea plants exhibited lower leaf chlorosis, progressive wilting, drying, collar and root discoloration, root bark peeling and extensive root deterioration. The pathogen was isolated on Potato Dextrose Agar (PDA), producing dirty-white mycelium that gradually turned grey to black, with abundant black microsclerotia after 7-8 days. Microscopic examination revealed septate, light- to dark-brown hyphae and spherical to oval microsclerotia. Pathogenicity was confirmed under glasshouse conditions, with characteristic symptoms appearing within 15-20 days after sowing and successful re-isolation of the pathogen. Seven natural farming inputs were evaluated in-vitro at 20% concentration using the poisoned food technique. Beejamrit recorded the greatest inhibition of mycelial growth (90.29%) with colony diameter (8.67 mm), followed by Jeevamrit (64.14%), Cow urine (40.35%), Ghanjeevamrit (27.58%), Neem cake (25.37%), Ramban (22.41%) and Sour buttermilk (11.95%). Under pot culture conditions, combined application of natural inputs was more effective than individual treatments. Treatment T6, comprising Neem cake 1 t/ha (SA) + 20% Beejamrit 200 ml/kg (ST) + 10% Jeevamrit 500 L/ha at 30, 45, 60 DAS (FS), recorded the highest germination (86.67%), root length (12.60 cm), shoot length (26.17 cm), plant height (31.16 cm) and vigour index (3008.66). It also resulted in the lowest disease incidence (11.57%) and maximum disease reduction over control (85.23%). The study demonstrated that strategic integration of natural farming inputs, particularly Neem cake, Beejamrit and Jeevamrit, can effectively suppress dry root rot and promote chickpea growth.

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