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Accueil du site → Doctorat → Inde → 2015 → Selection and utilization of Fluorescent Pseudomonads for enhancing production of sunflower crop in arid soil infested with Macrophomina phaseolina

Babasaheb Bhimrao Ambedkar University (2015)

Selection and utilization of Fluorescent Pseudomonads for enhancing production of sunflower crop in arid soil infested with Macrophomina phaseolina

Tewari, Sakshi

Titre : Selection and utilization of Fluorescent Pseudomonads for enhancing production of sunflower crop in arid soil infested with Macrophomina phaseolina

Auteur : Tewari, Sakshi

Université de soutenance : Babasaheb Bhimrao Ambedkar University

Grade : Doctor of Philosophy (PhD) 2015

Sommaire partiel
Sunflower is one of the fastest growing oilseed crop grown in India. Use of sunflower oil is in great demand as it trims down the incidence of cancer, hypertension, and the cholesterol in human beings. However, nowadays sunflower production is affected badly by several biotic and abiotic stresses. Amongst abiotic factors salinity is the main constraint that limits sunflower yield, whereas in biotic factors M. phaseolina is the phytopathogen which needs to be tackled in an ecofriendly and sustainable manner. M. phaseolina is fungal opportunist that likes to take advantage of stressed plant particularly in salinized regions and causes significant reduction in yields. Continuous use of chemicals in agriculture has resulted in degradation of soil fertility, formation of barren lands, disruption of soil ecology, development of resistant pathogens and ill effects on human health. Hence, there is an emergent need to develop biopreparations which can enhance plant growth, control phytopathogens, are effective even under stress conditions and above all are ecofriendly and hence lead to sustainability. Microbe-based formulations that can suppress the growth of phytopathogens and ameliorate the effect of abiotic stresses such as salinity are real alternatives to hazardous chemicals. In the present study, 110 fluorescent Pseudomonads were isolated from Kanpur (Uttar Pradesh) and adjoining areas. Isolates were characterized on the basis of morphological, physiological, biochemical and molecular basis. The vernacular name ‘fluorescent Pseudomonas group PF07-PF23 was coined for a group of 17 isolates from the rhizosphere of sunflower having characteristics that differentiate them from other members of fluorescent Pseudomonas spp. The isolates were monitored for stress tolerance capacity, plant growth promoting traits and biocontrol potential against M. phaseolina. On the basis of these attributes, two potent isolates, PF17 and PF23, were selected as they displayed maximum salt, temperature and pH tolerance. In nature all the stress conditions occur simultaneously hence multi - stress tolerance assay was conducted to check the survivability of isolates. Isolates displayed survivability when multiple shocks (of salinity, temperature and pH) were given simultaneously. Selected isolate PF23 was subjected to 16S rRNA gene sequence analysis, and was found to be P. aeruginosa. The 16S - 23S ITS region from PF17 gave a single amplicon of the size of 560 bp, which confirmed that the isolate was P. fluorescence. Protease, elastase and gelatinase activities of both the strains were checked so as to determine the pathogenicity. These initial level tests confirmed that both the strains were non-pathogenic, a virulent and hence safe to use. However, clinical trials will also be performed to completely ensure the safety before using these strains at large scale.

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Page publiée le 28 février 2021