Indigenous rhizosphere microbial consortium from a Fusarium-suppressive soil attenuates combined salinity and Fusarium wilt stress in tomato (Solanum lycopersicum cv. Pusa Ruby)

¹ Amity Institute of Organic Agriculture, Amity University, Sector-125, Noida 201303, Uttar Pradesh, India
² Amity Food & Agricultural Foundation, Amity University, Noida, Uttar Pradesh 201301, India

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Abstract

Combined salinity and soil-borne Fusarium wilt limit tomato production in salt-affected belts of north-western India. Most field interventions still rely on single-strain inoculants. We tested whether a crude indigenous rhizosphere microbial consortium (RMC) recovered from a healthy tomato in a Fusarium-affected saline village soil could attenuate combined abiotic and biotic stress in Solanum lycopersicum cv. Pusa Ruby. A randomized block pot experiment with seven treatments (n = 3 pots, 2 plants per pot) crossed organic versus saline soil with the presence or absence of Fusarium oxysporum f. sp. lycopersici (FOL, 10⁵ spores g^-1 soil) and with or without 5 mL of RMC slurry per plant. Plant height, branch number and disease severity index (DSI) were recorded at 20, 40 and 60 days after transplanting. Under combined stress without RMC, plant height at 60 days after transplanting was 48.7% lower than the unstressed control and mean DSI reached 46%. Application of RMC under the same combined stress increased plant height by 75.3% relative to the no-RMC contrast (within 10% of the unstressed control) and reduced mean DSI to 10% (a 78.3% relative reduction). Plant height was strongly inversely associated with DSI across treatments (R² = 0.99, n = 7 treatment means). The RMC effect was largest under combined stress and smallest under Fusarium -only stress. Whole-community rhizosphere transplants from suppressive soils merit field-scale evaluation as a low-cost amendment for marginal saline lands.