Effets des rhizobactéries PGPR sur le rendement et les teneurs en macroéléments du maïs sur sol ferralitique non dégradé au Sud-Bénin

L’objectif de l’étude est d’évaluer les effets de 15 rhizobactéries promotrices de croissance végétative (PGPR en Anglais) sur le rendement et l’état nutritionnel des plants de maïs sur sol ferralitique non dégradé du Sud-Bénin. Les semences de maïs ont été inoculées avec des concentrations microbiennes d’environ 108 UFC/ml. Les teneurs en azote, en phosphore et en potassium d’échantillons de plants de maïs ont été déterminées. Les valeurs de rendement du maïs ont été soumises à une analyse de la variance à deux facteurs. Les rhizobactéries Pseudomonas fluorescens ont induit le rendement de maïs le plus élevé, dépassant de 41,46% le rendement de maïs obtenu avec l’inoculation de P. putida et de 118,05% le rendement de maïs obtenu au niveau des plants non inoculés. Les rendements de maïs induits par P. putida et Azospirillium lipoferum sont supérieurs respectivement de 54,17% et de 26,39% au rendement obtenu au niveau des plants non inoculés. Les résultats obtenus augurent de la possibilité d’utiliser les rhizobactéries PGPR comme des engrais biologiques pour une production durable de maïs. Au Sud du Bénin, où la pression démographique est forte et la baisse de la fertilité des sols croissante, l’utilisation de méthodes biologiques pour accroître les récoltes est une solution incontournable.Mots clés: Rhyzobactéries, Rendement, Maïs, Sol ferralitique, Béni

Metabolic and biofungicidal properties of maize rhizobacteria for growth promotion and plant disease resistance

Plant growth promoting rhizobacteria (PGPR) are known to influence plant growing both by direct and/or indirect mechanisms. This study aimed to establish PGPR profile of 15 bacteria isolated from maize (Zea mays L.) rhizosphere in Benin. These rhizobacteria were screened in vitro for the  plant growth promoting traits like production of indole acetic acid (IAA), ammonia (NH3), hydrogen cyanide (HCN), catalase, exopolysaccharides and antifungal activity against phytopathogenic fungi for example Fusarium verticillioides, that is an important maize pathogenic. Most rhizobacteria strains were found to produce catalase (100%), exopolysaccharides (100%), ammonia (86.66%), hydrogen cyanide (80%) and indole acetic acid (60%). Pseudomonas putida, Pseudomonas fluorescens and Azospirillum lipoferum have highly produced many of the investigated metabolites. Streptomyces  hygroscopicus, Streptomyces  fasciculatus, Pseudomonas aeruginosa, P. putida, P. fluorescens and A. lipoferum inhibited mycelial growth of F. verticillioides and Aspergillus ochraceus. P. fluorescens and P. aeruginosa were highly antagonistic against F. verticillioides (52.24% of mycelial growth inhibition) and A. ochraceus (58.33% of mycelial growth inhibition). These results suggest the possibility to use these rhizobacteria as biological fertilization to increase maize yield and the biological control of F. verticillioides and A. ochraceus. Key words: Rhizobacteria, Plant growth promoting rhizobacteria (PGPR), antifungal activities, biological control, Benin

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Not AvailableThe increasing demand for crop production, given worldwide increases in the human population, puts pressure on moving natural resources towards sus-tainable development. This creates a big challenge for the upcoming generation. If improvement is not successful, there exists the unfortunate consequence that global food production may soon become insufficient to feed all of the world’s people. It is therefore essential that agricultural productivity be significantly increased in a more sustainable and environmentally friendly approach. Plant-beneficiary rhizo-bacteria (PBR) naturally activate microorganisms found in the soil. Because they are inexpensive, effective, and environmentally friendly, PBR are gaining impor-tance for use in crop production by restoring the soil’s natural fertility and protect-ing it against drought and soil diseases, thereby stimulating plant growth. PBR decrease the use of chemical fertilisers, pesticides, and artificial growth regulators; the intensive use of these inputs has led to severe health and environmental hazards, such as soil erosion, water contamination, pesticide poisoning, decreased ground-water table, water logging, surface crusting and depletion of biodiversity. The use of PBR has been proven to be an environmentally sound way of increasing crop yields by facilitating plant growth through either a direct or indirect mechanism with the aim of sustaining soil health over the long term. (7) (PDF) Towards Plant-Beneficiary Rhizobacteria and Agricultural Sustainability. Available from: https://www.researchgate.net/publication/325854138_Towards_Plant-Beneficiary_Rhizobacteria_and_Agricultural_Sustainability [accessed Nov 19 2018].Not Availabl