In-vitro & In-vivo Studies on Antimicrobial and Plant Growth Promoting Efficacy of Fluorescent Pseudomonads

Aims: Excessive use of chemical fungicides cause environmental pollution and its residual effects are deleterious for human and animal consumption. So, application of biological control agents in IDM is an ecofriendly complement to manage the diseases as well as to protect the environment. PGPRs are free living microorganisms which have antimicrobial properties as well as exert beneficial effects to plant growth.

Study Design: This present study has been designed to identify potential indigenous fluorescent Pseudomonads strains from different crop ecosystems under Eastern Gangetic plains of West Bengal. Study of Plant growth promoting properties and antimicrobial properties were done under both in-vitro and in vivo condition.

Place and Duration of Study: Uttar Banga Krishi Viswavidyalaya, Pundibari, Cooch Behar, West Bengal, Duration 03years

Methodology: Under this experiment 22 bacterial isolates were isolated and purified from different rhizosphere. Isolates were identified based on different biochemical test like catalase, oxidase activity, citrate utilization. The major plant growth promoting properties like P, K and Zn solubilisation efficiency were tested. In-vitro antimicrobial properties were also tested like HCN production, Volatile and non volatile compounds production etc. Based on in-vitro performance, best performing isolate was selected for in-vivo in Lentil against Stemphylium botryosum, a major disease causing fungi of lentil. IDM practice was done in three stages like Seed treatment, Prophylactic spray and Therapeutic spray and three lentil variety WBL 77(Maitree), Pusa Ageti and MN12 were used.

Results: Most of the isolates showed positive result in biochemical tests and performed well i.r.o. PGP properties and antimicrobial properties. In field trial UBPF5 gave a promising result. PF5 isolate was identified through 16S rRNA based molecular method and sample showed 99.25% similarity with Pseudomonas gessardii based on nucleotide homology and phylogenetic analysis. In comparison to different combination of treatments cuprous chloride as seed treatment, Pseudomonas sp. as prophylactic spray and for therapeutic purpose Boscalid + Pyroclostrobin were found mostly efficient in respect of disease incidence as well as plant growth and yield. Prophylactic spray with Pseudomonas sp. in combination with biological seed treatment and therapeutic application of fungicide has resulted in 26-38% reduction in disease incidence and 28-32% increment in yield.

Conclusion: So, use of PGPR in combination with chemical fungicides is an eco-friendly tool to manage plant diseases in a sustainable manner.