GNOTOBIOTIC CULTURES OF RICE PLANTS UP TO EAR STAGE IN THE ABSENCE OF COMBINED NITROGEN SOURCE BUT IN THE PRESENCE OF FREE LIVING NITROGEN FIXING BACTERIA AZOTOBACTER VINELANDII AND RHODOPSEUDOMONAS CAPSULATA

• Published in: Plant and soil 1981-01, Vol.60 (1), p.85-97
• Main Authors: MAUDINAS, B., CHEMARDIN, M., YOVANOVITCH, E., GADAL, P.
• Format: Article
• Language: English
• Subjects: Azotobacter vinelandii; Bacteria; Gnotobiotics; Nitrogen; Nitrogen fixation; Oryza sativa; Plant roots; Plants; Rhizosphere; Rhodobacter capsulatus; Rhodopseudomonas capsulata; Rice
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/BF02377114

An all glass tight growth chamber, entirely sterilizable, has been constructed to carry out axenic and gnotobiotic cultures of rice plants (Oryza sativa L.). When grown in liquid medium and in the absence oí combined nitrogen but in the presence of the diazotrophs Azotobacter vinelandii and Rhodopseudomonas capsulata, rice plants exhibited a complete biological cycle from germination up to ear stage, during a period of time similar to the one encountered in french paddy soil of Camargue. In one experiment, mannitol was given to rice culture medium together with Azotobacler vinelandii and Rhodopseudomonas capsulata. In another experiment, mannitol was not given together with Rhodopseudomonas, and still positive nitrogen gain was obtained, although it was less than culture with mannitol. When ¹⁵N labeled cells of Rhodopseudomonas were added in rice culture medium, ¹⁵N was partly transferred to rice plant. Among the nitrogen substances excreted from the bacteria in the rhizosphere medium, large organic molecules were shown to be the most abundant in our experimental conditions. Moreover, the concentration of free ammonia or aminoacids present in the rice rhizosphere were always compatible with a bacterial nitrogenase activity.