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 bacteriaAzotobacter vinelandii andRhodopseudomonas capsulata

Abstract

SUMMARYAn 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 of 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 Azotobacter 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 1 s N 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.

Isolation of potential phototrophic purple non-sulphur bacteria in paddy and their effects on paddy seedlings in hydroponic culture

“…Based on others findings confirmation with this paper result it can be concluded that inoculation gives benefits to rice seedling growth that almost commensurate with the addition of 40 ppm of nitrogen (ammonium chloride). This result is in harmony with the findings of others (Lee et al, 1977;Maudinas et al, 1981;Elderly and Elbanna 1999;Ramchander et al, 2012). With all these supportive findings and obtained results, PPNSB group of bacterium definitely have plant growth promoting activity.…”

“…Kobayashi and Haque (1971) suggested a possible growth-promoting role of phototrophic purple non-sulphur bacteria (PPNSB) in rice fields. Maudinas et al (1981) showed that in the absence of chemical nitrogen (Ammonium chloride), but in the presence of the diazotrophs Azotobacter vinelandii and Rhodopseudomonas capsulatus (now Rhodobacter capsulatus) in a liquid medium, rice plants can benefit from germination up to ear stage. Eldin and Elbanna (2011) also showed field evidence for the potential of Rhodobacter capsulatus as biofertilizer for flooded rice.…”

Enhancement of growth and yield of tomato by Rhodopseudomonas sp. under greenhouse conditions

“…The pigments, metabolites, and nutrients made by PNSB could give some positive effects on plant growth. Although nitrogen fixation (Maudinas et al, 1981) and auxin production (Rajasekhar et al, 1999) by PNSB have been reported, a systematic field application of PNSB for growth promotion and quality improvement of agricultural crops has not been carried out many times. In our previous study, isolated PNSB strains Rhodopseudomonas sp.…”

Purple non‐sulphur bacteria and plant production: benefits for fertilization, stress resistance and the environment

“…Purple non‐sulphur bacteria are distributed in various habitats exposed to sunlight and atmospheric N 2 (including paddy fields), and their contribution to rendering nitrogen bioavailable to plants has been demonstrated. For instance, when inoculated in a hydroponic nutrient solution lacking a nitrogen source, ammonium was detected in the medium (< 10 μM) (Maudinas et al ., ). Therefore, PNSB being one of the dominant species in paddy fields (Elbadry et al ., ,) significantly contribute to nitrogen fertility as rice yields can reach values up to 2.0–3.5 ton of nitrogen per hectare using only nitrogen originating from soil organic matter and biological N 2 fixation (Kundu and Ladha, ).…”

“…For example, Maudinas et al . () inoculated R. capsulatus B10 in a hydroponic medium (deprived of a nitrogen source), and this strain alone was unable to sustain plant growth in such a system. On the other hand, Elbadry and Elbanna () used R. capsulatus DSM 155 in a similar experiment, where normal plant growth was observed.…”