Author(s): Bertrand H, Plassard C, Pinochet X, Touraine B, Normand P,
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Abstract A plant growth-promoting rhizobacterium belonging to the genus Achromobacter was isolated from the oil-seed-rape (Brassica napus) root. Growth promotion bioassays were performed with oilseed rape seedlings in a growth chamber in test tubes containing attapulgite and mineral nutrient solution, containing NO3- as N source. The presence of this Achromobacter strain increased shoot and root dry weight by 22-33\% and 6-21\%, respectively. Inoculation of young seedlings with the Achromobacter bacteria induced a 100\% improvement in NO3- uptake by the whole root system. Observations on the seminal root of seedlings 20 h after inoculation showed that there was an enhancement of both the number and the length of root hairs, compared to non-inoculated seedlings. Electrophysiological measurements of NO3- net flux with ion-selective microelectrodes showed that inoculation resulted in a specific increase of net nitrate flux in a root zone morphologically similar in inoculated and non-inoculated plants. The root area increased due to root hair stimulation by the Achromobacter bacteria, which might have contributed to the improvement of NO3- uptake by the whole root system, together with the enhancement of specific NO3- uptake rate. Moreover, inoculated plants showed increased potassium net influx and proton net efflux. Overall, the data presented suggest that the inoculation of oilseed-rape with the bacteria Achromobacter affects the mineral uptake.
This article was published in Can J Microbiol
and referenced in Journal of Fertilizers & Pesticides