Evaluation of Nitrogen Fixation in Sorghum Cultivars Inoculated with Different Strains of Azospirillum spp.

Christiansen-Weniger, C.; Boddey, Robert M.; Döbereiner, Johanna

doi:10.1007/978-3-642-70791-9_17

Cited by 7 publications

(3 citation statements)

References 10 publications

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“…suggested that aluminium tolerance of grasses may be used for the selection of plant genotypes with a high affinity to rhizosphere nitrogenase activity. In a previous experiment with sorghum cultivars of different resistance against free aluminium we also observed that aluminium-tolerant cultivars had significantly higher associative N 2 fixation rates than an aluminium-sensitive cultivar (Christiansen-Weniger et al, 1985). …”

Section: Discussionmentioning

confidence: 93%

“…Inoculation experiments show widespread results, from no or even a negative effect (Owens, 1977;Schank et al, 1980) to a plant nitrogen increase of more than 120% (Cohen et al, 1980;Kapulnik et al, 1981a). Significant differences in response to Azospirillum inoculation are reported even between cultivars of the same plant species (Christiansen-Weniger et al, 1985;Wani et al, 1984).…”

Section: Introductionmentioning

confidence: 99%

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Associative N2 fixation and root exudation of organic acids from wheat cultivars of different aluminium tolerance

Christiansen-Weniger¹,

Groneman²,

Veen³

1992

Plant Soil

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Three wheat cultivars with different tolerances against free aluminium were grown monoxenically in association with Azospirillum brasilense. In situ nitrogen fixation, measured with the acetylene reduction assay, was higher by the aluminium-tolerant cultivars than by the sensitive cultivar. The transfer of fixed nitrogen to the host plant, determined by the 15N dilution technique, was also significantly higher in the aluminium-resistant wheat plants. The total accumulation of fixed nitrogen in the host plants due to an A. brasilense inoculation varied from approximately 13% to 17% of the total nitrogen in the root and 2.9% to 3.9% of the nitrogen in the shoot.The quantity and quality of exudates released in liquid nutrient solution were analysed separately for two of the wheat cultivars, one aluminium-tolerant and one aluminium-sensitive. After 29 days of growth the aluminium-tolerant plants exudated significantly higher total amounts of carbon than aluminium-sensitive plants. No differences between the two cultivars existed in the carbon exudation rate per gram dry root.Much higher concentrations of low molecular dicarboxylic acids i.e. succinic, malic and oxalic acid, were found in the exudates of aluminium-tolerant plants. Dicarboxylic acids are potential chelating compounds for positively charged metals such as aluminium and they may play an important role in protecting the plant against aluminium incorporation. They are also very suitable substrates for Azospirillum spp. It is therefore suggested that these factors may be causing the higher associative nitrogen fixation rates which was found in the aluminium-tolerant wheat cultivars.

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Section: Discussionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Associative N2 fixation and root exudation of organic acids from wheat cultivars of different aluminium tolerance

Christiansen-Weniger¹,

Groneman²,

Veen³

1992

Plant Soil

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“…which are transferred to their host plants appear to be small (3,21,29). Investigations in which the 15N isotope dilution technique was used indicated that most of the fixed nitrogen remained below ground, probably still bound to bacterial cells, and contributed only very little to the upper plant parts (7,34,38). In experiments performed with wheat plants that were monoxenically associated with Azospirillum brasilense, only 1 to 2% of the shoot nitrogen originated from atmospheric sources (6a).…”

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confidence: 99%

NH ₄ ⁺ -Excreting Azospirillum brasilense Mutants Enhance the Nitrogen Supply of a Wheat Host

Christiansen-Weniger¹,

Veen²

1991

Appl Environ Microbiol

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Spontaneous ethylenediamine-resistant mutants of Azospirillum brasilense were selected on the basis of their excretion of NH4'. Two mutants exhibited no repression of their nitrogenase enzyme systems in the presence of high (20 mM) concentrations of NH4'. The nitrogenase activities of these mutants on nitrogen-free minimal medium were two to three times higher than the nitrogenase activity of the wild type. The mutants excreted substantial amounts of ammonia when they were grown either under oxygen-limiting conditions (1 kPa of 02) or aerobically on nitrate or glutamate. The mutants grew well on glutamate as a sole nitrogen source but only poorly on NH4Cl. Both mutants failed to incorporate ["4C]methylamine. We demonstrated that nitrite ammonification occurs in the mutants. Wild-type A. brasilense, as well as the mutants, became established in the rhizospheres of axenically grown wheat plants at levels of >107 cells per g of root. The rhizosphere acetylene reduction activity was highest in the preparations containing the mutants. When plants were grown on a nitrogen-free nutritional medium, both mutants were responsible for significant increases in root and shoot dry matter compared with wild-type-treated plants or with noninoculated controls. Total plant nitrogen accumulation increased as well. When they were exposed to a 15N2-enriched atmosphere, both A. brasilense mutants incorporated significantly higher amounts of '5N inside root and shoot material than the wild type did. The results of our nitrogen balance and '5N enrichment studies indicated that NH4+-excreting A. brasilense strains potentially support the nitrogen supply of the host plants.

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N2-fixation by ammonium-excreting Azospirillum brasilense in auxine-induced root tumours of wheat (Triticum aestivum L.)

Christiansen-Weniger¹

1992

Biol Fertil Soils

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Evaluation of Nitrogen Fixation in Sorghum Cultivars Inoculated with Different Strains of Azospirillum spp.

Cited by 7 publications

References 10 publications

Associative N2 fixation and root exudation of organic acids from wheat cultivars of different aluminium tolerance

Associative N2 fixation and root exudation of organic acids from wheat cultivars of different aluminium tolerance

NH ₄ ⁺ -Excreting Azospirillum brasilense Mutants Enhance the Nitrogen Supply of a Wheat Host

N2-fixation by ammonium-excreting Azospirillum brasilense in auxine-induced root tumours of wheat (Triticum aestivum L.)

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Evaluation of Nitrogen Fixation in Sorghum Cultivars Inoculated with Different Strains of Azospirillum spp.

Cited by 7 publications

References 10 publications

Associative N2 fixation and root exudation of organic acids from wheat cultivars of different aluminium tolerance

Associative N2 fixation and root exudation of organic acids from wheat cultivars of different aluminium tolerance

NH 4 + -Excreting Azospirillum brasilense Mutants Enhance the Nitrogen Supply of a Wheat Host

N2-fixation by ammonium-excreting Azospirillum brasilense in auxine-induced root tumours of wheat (Triticum aestivum L.)

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NH ₄ ⁺ -Excreting Azospirillum brasilense Mutants Enhance the Nitrogen Supply of a Wheat Host