Rôle d'une bactérie productrice d'exopolysaccharides (Rhizobium sp.) dans l'agrégation du sol rhizosphérique du tournesol : conséquences de l'inoculation sur la structuration du sol et la nutrition minérale de la plante

Abstract : The bacterial strain Y AS34, selected for exopolysaccharide (EPS) production, was isolated from the rhizoplane of sunflower (Helianthus annuus) in a Dystric Cambisol. From cartography and sequencing of the 16S rDNA gene it was concluded that strain Y AS34 belongs to the genus Rhizobium. The gelatinous EPS produced by this strain was different from succinoglycan usually produced by bacteria belonging to the genus Rhizobium. In the presence of 1 % (w/w) of the EPS purified from strain Y AS34, the water holding capacity of soil from St-Florent-sur-Cher was enhanced by 50%. Inoculation of sunflower seeds and soil with strain Y AS34 led to a significant increase of rootadhering soil mass per root biomass (+80%), under both, water stress and normal water supply conditions. Concomittantly with this bacterial effect on the mass of root-adhering soil, an increase of soil macro-porosity (pore diameter between 5 and 50 mm) was observed. In addition to these physical changes of root-adhering soil, nitrogen uptake by sunflower was significantly increased after inoculation with Rhizobium sp. Y AS34 in the presence of 1 N-nitrates. Strain y AS34 seems to modify the soil structure around the root system in a way that the water supply of sunflower and its nitrogen uptake is increased counteracting the effect of water deficit on sunflower growth.
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http://docnum.univ-lorraine.fr/prive/SCD_T_1997_0169_ALAMI.pdf
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Submitted on : Thursday, March 29, 2018 - 11:00:15 AM
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Younes Alami. Rôle d'une bactérie productrice d'exopolysaccharides (Rhizobium sp.) dans l'agrégation du sol rhizosphérique du tournesol : conséquences de l'inoculation sur la structuration du sol et la nutrition minérale de la plante. Sciences agricoles. Université Henri Poincaré - Nancy 1, 1997. Français. ⟨NNT : 1997NAN10169⟩. ⟨tel-01747448⟩

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