Root respiration and bacterial population of roots I. Effect of nitrogen source, potassium nutrition and aeration of roots

Trolldenier, G.; Rheinbaben, W. Von

doi:10.1002/jpln.19811440405

Cited by 29 publications

(12 citation statements)

References 13 publications

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“…2). This is opposite to findings by Trolldenier and von Rheinbaben (1981a) for wheat and Trolldenier (1973) for rice who observed that with NH4+-nutrition, bacterial abundances on roots were higher than with NO3--nutrition in hydroponic culture. The lower numbers of bacteria with NH4 ÷ could be the result of lower pH on the root surface due to release of protons with NH4 ÷ uptake (Marschner et al, 1986).…”

Section: Discussioncontrasting

confidence: 56%

“…Kraffczyk et al (1984) measured the rate of exudation of sugars, organic acids and amino acids from maize roots grown in nutrient solution at different potassium levels. Low potassium supply significantly increased the total amount of sugars, organic acids and amino acids exuded per gram root dry matter and this presumably explains the higher numbers of total bacteria on roots and the higher respiration rates initially found at low potassium level by Trolldenier and von Rheinbaben (1981a;.…”

Section: Introductionmentioning

confidence: 96%

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Root exudation and rhizoplane bacterial abundance of barley (Hordeum vulgare L.) in relation to nitrogen fertilization and root growth

et al. 1990

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The abundance of bacteria in the rhizoplane of barley varieties was investigated at different soil nitrogen levels. Increased amendments of nitrogen resulted in higher bacterial numbers in the rhizoplane of barley seedlings of different varieties. A negative correlation was found between nitrogen level in the soil and the growth rate of the seedling roots. The effect of nitrogen on the bacterial abundances could be indirect through changed root growth and thereby changed exudation. The exudation of soluble organic carbon compounds from barley seedling roots were measured in hydroponic culture. The effect of natural variation in root growth rate and of different concentrations of nitrogen in the nutrient solution was investigated. The amount of exudates constituted 2-66% of the dry weight increase in root biomass, depending on the root growth. Slower growing roots released considerably more organic carbon per unit root weight than faster growing roots. The variation in root exudation appeared to be mainly explained by differences in root growth, rather than of the nitrogen concentration in the nutrient solution. A significantly higher exudation rate was found during day time compared to night.

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Section: Discussioncontrasting

confidence: 56%

Section: Introductionmentioning

confidence: 96%

Root exudation and rhizoplane bacterial abundance of barley (Hordeum vulgare L.) in relation to nitrogen fertilization and root growth

et al. 1990

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“…1991;Cramer and Lewis 1993;Lang and Kaiser 1994;Martins-Loucao et al 2000), reports concerning its role in carbon and nitrogen partitioning in the rhizosphere are scanty. Higher root respiration due to ammonium rather than nitrate nutrition was partly attributed to increased root exudation and hence stimulation of bacterial growth (Trolldenier and von Rheinbaban 1981). Ammonium nutrition rather than nitrate nutrition is reported to increase root exudation by wheat roots, leading to increased lesion severity of the take-all fungus Gaeumannomyces graminis (Brown and Hornby 1987).…”

Section: Introductionmentioning

confidence: 99%

Sugar exudation by roots of kallar grass [ Leptochloa fusca (L.) Kunth] is strongly affected by the nitrogen source

Mahmood¹,

Woitke²,

Gimmler³

et al. 2002

Planta

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Exudation of sugars (glucose, fructose and sucrose) and that of cations and anions from intact roots of kallar grass [Leptochloa fusca (L.) Kunth] grown hydroponically with ammonium or nitrate (3 mM) as N source was investigated. In different experiments, plants grown on ammonium had slightly higher sugar contents than nitrate-grown plants, but their total sugar exudation during a 2-h period was up to 79-fold higher than under nitrate nutrition. Relative root exudation of inorganic anions and cations and that of amino acids (as a percentage of the internal contents exuded per time) was either similar or slightly higher from ammonium-grown than from nitrate-grown plants. Analysis of root architectural parameters revealed that ammonium-grown plants had a higher number of root tips/side roots per gram root fresh weight than nitrate-grown plants, whereas other root parameters, viz. length, diameter, volume and surface area were similar under the two N sources. A majority of the fine roots having diameter up to 0.4 mm represented up to 86% of the total root length, 64% of the total root surface area, and 35% of the total root volume; the root length and surface area per root system of that major root population were similar in ammonium- and nitrate-grown plants. Apparently, root architecture was not responsible for the different exudation rates. Within 12-24 h after shifting ammonium-grown plants to nitrate nutrition, root sugar levels and visible root architecture remained unchanged, yet the sugar exudation rate was reduced 30-fold. Short-term uptake of [14C]glucose (10 microM) from the rooting medium was similar for ammonium- and nitrate-grown plants. Thus, the very different sugar exudation rates were neither related to internal root sugar concentration, nor to the different root architecture, nor to differential resorption of sugars by ammonium- versus nitrate-grown plants. Increased external Ca2+ did not alter sugar exudation, and decreased external pH (4.5) only slightly increased sugar exudation from roots of nitrate-grown plants kept at pH 6.5. It is suggested that the much higher sugar exudation in response to ammonium may facilitate the ecologically and economically important association of diazotrophs with kallar grass roots.

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“…CO 2 concentration was higher in the rhizosphere than in non-rhizosphere soil, especially in pot experiments; a likely result of greater microbial population and respiration in the rhizosphere (Trolldenier and Rheinbaben, 1981). Indeed, based on the measurements of microbial respiration, it was reported that microbial activity in the rhizosphere was 2-4 times higher than in the bulk soil (Lynch and Wood, 1988).…”

Section: Discussionmentioning

confidence: 99%

Ethylene and carbon dioxide concentrations of soils as influenced by rhizosphere of crops under field and pot conditions

Otani

1993

Plant Soil

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A method for collecting low volumes of soil gas from a small region, and a technique for determining small concentrations of ethylene using an enrichment process are described. Using these methods, it was found that ethylene and carbon dioxide (CO2) concentrations of soils varied considerably depending on the presence or absence of a rhizosphere. Ethylene was much higher (31-375 nL L-l; mean: 207) in non-cropped areas (i.e., soils without rhizosphere) than in the rhizosphere region (8-136nL L-l; mean: 38) of a field in which maize or soybean were grown. On the other hand, CO 2 concentrations were higher in rhizosphere than in non-rhizosphere soil, especially in pot experiments. The rate of ethylene decomposition was, however, much greater in rhizosphere soil (55 nL g-i day-l) than in non-rhizosphere soil (34 nL g-I day-i). Higher microbial activity was presumed to result in the decrease of ethylene concentration and the increase in CO 2 in rhizosphere regions. The implications of these results in relation to the influence of ethylene in rhizosphere on plant growth, and the role of soil microbes on decomposition of ethylene is discussed.

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Root respiration and bacterial population of roots I. Effect of nitrogen source, potassium nutrition and aeration of roots

Cited by 29 publications

References 13 publications

Root exudation and rhizoplane bacterial abundance of barley (Hordeum vulgare L.) in relation to nitrogen fertilization and root growth

Root exudation and rhizoplane bacterial abundance of barley (Hordeum vulgare L.) in relation to nitrogen fertilization and root growth

Sugar exudation by roots of kallar grass [ Leptochloa fusca (L.) Kunth] is strongly affected by the nitrogen source

Ethylene and carbon dioxide concentrations of soils as influenced by rhizosphere of crops under field and pot conditions

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