Nitrogen Metabolism of Halophytes Ii. Nitrate Availability and Utilization

Stewart, George R.; Lee, J. A.; Orebamjo, T. O.

doi:10.1111/j.1469-8137.1973.tb04405.x

Cited by 114 publications

(44 citation statements)

References 11 publications

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“…Determinations of nitrate reductase activity, normally in triplicate, were made using the field assay technique described in a previous paper (Stewart et al, 1973). In species with low activities, the propanol, nitrate and phosphate concentrations and the pH of the assay solution were varied to determine optimal conditions.…”

Section: Methodsmentioning

confidence: 99%

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Nitrate Utilization by Species From Acidic and Calcareous Soils

1974

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SUMMARYNitrate utilization by calcicole and calcifuge species has heen measured using a field assay for nitrate reductase. Certain calcifuge species, notably members of the Ericaceae, showed no detectable enzyme activity in the field and very low values in the laboratory even after nitrate feeding. It is concluded that these species have a restricted ability to utilize nitrate. Other calcifuge species and all the species from calcareous soils had detectable nitrate reductase activities in the field and responded to nitrate addition by large increases in enzyme activities. Some of these species were used to compare nitrate utilization in a number of acidic and calcareous soils. Nitrate was utilized in all the soils, but utilization was minimal in ombrogenous peat. A comparison of closely adjacent acidic and calcareous soils showed that nitrate is an important source of inorganic combined nitrogen in at least some acidic soils.

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Section: Methodsmentioning

confidence: 99%

“…Plant analyses were carried out as described by Stewart et al (1972). ' Determinations of nitrate reductase activity, normally in triplicate, were made using the field assay technique described in a previous paper (Stewart et al, 1973).…”

Section: Methodsmentioning

confidence: 99%

Nitrate Utilization by Species From Acidic and Calcareous Soils

1974

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“…Nitrate reductase activity (NRA) of leaves was determined [14] . Five ml incubation medium comprising 100 mL 0.1 M phosphate buffer (PH 7.5), 1.5 g potassium nitrate and 1 mL 4% propan-1-ol, was used to incubate 0.4 g finely cut leaves from each replicate, for an hr at a room temperature of 30°C.…”

Section: Determination Of Nitrate Reductase Activitymentioning

confidence: 99%

Salicylic Acid Protects Nitrate Reductase Activity, Growth and Proline in Amaranth and Tomato Plants during Water Deficit

Umebese¹,

Olatimilehin²,

Ogunsusi³

2009

American J. of Agricultural and Biological Sciences

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Problem statement: Seedlings of Amaranthus hybridus cv. NHAC-3 (large green, amaranth) and Lycopersicum esculentum cv. Roma (tomato) were subjected to 7 days water stress at Early Vegetative (EV), Late Vegetative (LV), Early Flowering (EF) and Late Flowering (LF) stages of growth to study the impact on leaf water potential (ψ w ), Nitrate Reductase Activity (NRA), growth (plant height, shoot and root biomass) and proline content of both plants. Approach: Two concentrations of salicylic acid (1 and 3 mM SA) were applied to stressed plants to study the level of protection given by SA to the plants. Leaf ψ w was significantly reduced (p = 0.05) during stress treatment at nearly all stages of growth in both plants. Leaf ψ w was in the range -0.25 to -1.42 (unstressed) and -1.45 to -2.02 (stressed) in tomato plants while in amaranth it was -0.7 to -1.62 (unstressed) and -1.62 to -2.68 (stressed). As 3 mM SA increased leaf ψ w to values close to the control (unstressed plants). NRA was significantly (p = 0.05) reduced by stress treatment at the LV stage of amaranth, EF stage of tomato and LF stage of both plants. Results: Thus, the reduction of NRA was more pronounced at the reproductive stage of both plants. As 3 mM SA was effective in maintaining NRA at levels similar to the control in both plants. Stress treatment reduced plant height significantly (p = 0.05) at the vegetative stages of both plants and 3 mM was also effective in keeping plant height similar to the control. Though shoot biomass was affected by water stress, SA treatment was not very effective in preserving the biomass during stress. Root biomass of plants was reduced by stress treatment at the reproductive stage and only tomato plants responded positively to 3 mM SA. Proline content was only slightly increased at all stages of growth in stressed plants but 3 mM SA induced a two-fold increase in proline content at the vegetative stage of tomato (EV and LV) and significant increases (p = 0.05) at almost all stages of growth of amaranth. Conclusion/Recommendations: The build up of proline, an osmolyte, by SA in stressed plants increased the capacity of plants to absorb water from the soil as shown by the increase in leaf ψ w of both plants from -1.45 to -0.25 . SA was more effective in protecting the plants against the adverse effects of water stress when the stress was given at the vegetative stages (EV and LV) than at the flowering stages (EF and LF).

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“…A modification of the in vivo assay described by Stewart, Lee and Orebamjo (1973) was employed (Meade, 1982). Three capitula were placed in a large side-arm tube containing 5 cm^ of assay medium (100 mM phosphate buffer, pH 7-5, containing 75 mM potassium nitrate and 0-75 % propan-1-ol).…”

Section: Nitrate Reductase Assaymentioning

confidence: 99%

Nitrate Reductase Activity of Sphagnum Species in the South Pennines

Press

Lee

1982

New Phytologist

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SUMMARYBulk deposition of nitrate, ammonium and organic nitrogen was greater at a South Pennine blanket peat site than at a sinnilar, relatively unpolluted site in the Berwyn Mountains, North Wales. Sphagnum cuspidatum, transplanted from North Wales to the South Pennines, showed a rapid induction of nitrate reductase activity^ which declined after 4 days. A laboratory induction experiment demonstrated a sinnilar phenomenon on solutions containing 1 mM nitrate. In the presence of 1 mM ammonium, much less nitrate reductase activity was induced. Ammonium accumulated in both nitrate grown plants in the laboratory and in field transplants, which suggests that it may be responsible for the observed declines in enzyme activity. The results are discussed in relation to the nitrogen nutrition of blanket bog plants.

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Nitrogen Metabolism of Halophytes Ii. Nitrate Availability and Utilization

Cited by 114 publications

References 11 publications

Nitrate Utilization by Species From Acidic and Calcareous Soils

Nitrate Utilization by Species From Acidic and Calcareous Soils

Salicylic Acid Protects Nitrate Reductase Activity, Growth and Proline in Amaranth and Tomato Plants during Water Deficit

Nitrate Reductase Activity of Sphagnum Species in the South Pennines

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