The role of vesicular-arbuscular mycorrhizas (VAM) in the phosphorus nutrition of cowpea (Vigna unguiculata (L.) Walp)

1991 ◽  
Vol 42 (1) ◽  
pp. 129 ◽  
Author(s):  
BM Ikombo ◽  
DG Edwards ◽  
CJ Asher
Keyword(s):  
Vigna Unguiculata ◽  
Phosphorus Deficiency ◽  
Phosphorus Nutrition ◽  
Strong Increase ◽  
Phosphorus Concentration ◽  
Sequence Of Events ◽  
Mycorrhizal Association ◽  
Low Phosphorus ◽  
Unsterilized Soil

An experiment was conducted to establish the role of VAM in the phosphorus nutrition and early growth of cowpea (Vigna unguiculata (L.) Walp.) cv. Vita 4 in a podzolic soil (Haplustult). The experiment involved four treatments: (1) plants grown in unsterilized soil adequately supplied with phosphorus (240 kg P ha-1), (2) plants grown in unsterilized soil with low phosphorus (10 kg P ha-1), (3) and (4) plants grown in methyl bromide sterilized soil with low phosphorus (10 kg P ha-1). Plants in treatments (1), (2) and (3) were inoculated with Bradyrhizobium. A series of harvests was taken from 14 to 42 days after sowing; 15 harvests at two-day intervals from treatment (2) and 5 harvests at 7-day intervals from the other treatments. Root infection by VAM did not occur in plants grown in the sterilized soil treatments (3) and (4); growth of these plants was poor, and they showed symptoms of severe phosphorus deficiency. Phosphorus concentrations in the youngest fully expanded leaf (YFEL) of plants grown in treatments (3) and (4) were in the range 0.10 to 0.16% at all harvests. Plants which were grown in the unsterilized soil with 240 kg P ha-l (treatment (1)) grew very well; they had a high concentration of phosphorus (0.3 1 to 0.75%) in the YFEL at all harvests and exhibited a delayed and reduced level of infection by VAM. Plants grown in the unsterilized soil with 10 kg P ha-l (treatment (2)) were strongly colonized by VAM; infection was apparent at 14 days after sowing and reached a maximum (85% of root segments colonized) at 36 days after sowing. A strong increase in phosphorus concentration in the YFEL of plants grown in treatment (2) commenced at 22 days after sowing, while an increase in dry matter yield and phosphorus content of the whole tops above that of non-mycorrhizal plants grown in the sterilized soil was observed at 30 days after sowing. The sequence of events leads us to conclude that the recovery of cowpea plants from early phosphorus deficiency stress resulted from increased phosphorus absorption following the development of a mycorrhizal association with the roots.

Acid phosphatase activity of intact roots and phosphorus nutrition in plants. 1. Assay conditions and phosphatase activity

1980 ◽  
Vol 31 (3) ◽  
pp. 429 ◽  
Author(s):  
KD McLachlan
Keyword(s):  
Reaction Time ◽  
Phosphatase Activity ◽  
Microbial Contamination ◽  
Plant Root ◽  
Phosphorus Deficiency ◽  
Reaction Times ◽  
Subterranean Clover ◽  
Phosphorus Nutrition ◽  
Nitrophenyl Phosphate ◽  
Low Phosphorus

This veries sets out to investigate the possibility of developing root phosphatase activity as an indicator of plant efficiency in obtaining phosphorus from low phosphorus situations. This paper examines the effect of substrate pH, temperature, reaction time, microbial contamination and phosphorus nutrition on the expression of phosphatase activity of plant roots. Rye, wheat, buckwheat and subterranean clover plants have been used. Phosphatase (E.C. 3.1.3.4.1) activity measured by p-nitrophenyl phosphate (PNPP) assay was essentially the activity of the plant root. Increased acidity in the substrate, on its own, did not hydrolyse PNPP nor did microbial contamination significantly affect the plant value. Temperature and reaction time were positively related to the assay value, least variation in assay values occurring with substrate temperatures of 20�C and reaction times of 60-120 min. Optimum pH for phosphatase activity lay in the range pH 5-6. Deficient plants had greater activities than sufficient ones. There was no evidence of alkaline phosphatase activity with phosphorus deficiency. In wheat, the phosphatase activity increased within the first 4 days of plants being deprived of phosphorus and reached its peak in 8 days. Some of the phosphatase was soluble, but most was associated with the root itself. There was evidence that it could be strongly adsorbed on cellulose nitrate filters.

scholarly journals The effect of inoculation with arbuscular mycorrhizal fungus Rhizophagus irregularis on cytokinin content in a highly mycotrophic Medicago lupulina line under low phosphorus level in the soil

2017 ◽  
Vol 63 (No. 11) ◽  
pp. 519-524 ◽  
Author(s):  
Yurkov Andrey ◽  
Veselova Svetlana ◽  
Jacobi Lidia ◽  
Stepanova Galina ◽  
Yemelyanov Vladislav ◽  
...  
Keyword(s):  
Phosphorus Deficiency ◽  
Mycorrhizal Fungus ◽  
Arbuscular Mycorrhizal ◽  
Zeatin Riboside ◽  
Rhizophagus Irregularis ◽  
Medicago Lupulina ◽  
Hormone Balance ◽  
Low Phosphorus ◽  
Am Symbiosis

The study is focused on the elucidation of the role of cytokinins (CKs, zeatin and zeatin riboside) in the development of effective arbuscular mycorrhiza (AM) symbiosis with Medicago lupulina. An important mechanism involved in the regulation of host plant growth is supposed to be linked to the modulation of plant hormone balance. The data obtained revealed the formation of an effective AM-symbiosis (M. lupulina + Rhizophagus irregularis) under phosphorus-deficiency. At the shooting stage (35<sup>th</sup> day after sowing), it is characterized by a decrease in the root:shoot ratio, the lowering in arbuscules and vesicle abundances, but an increase in the intensity of mycelium development. Mycorrhized plants differed from the control ones by higher CK levels in both roots and leaves. Zeatin and zeatin riboside concentration exhibited uneven alterations over time. A role of mycelium in the modulation of CK balance has been discussed.

scholarly journals Mehlich 3 extractant used for the evaluation of wheat-available phosphorus and zinc in calcareous soils

2018 ◽  
Vol 64 (No. 2) ◽  
pp. 53-57 ◽  
Author(s):  
Sedlář Ondřej ◽  
Balík Jiří ◽  
Kulhánek Martin ◽  
Černý Jindřich ◽  
Kos Milan
Keyword(s):  
Stem Elongation ◽  
Phosphorus Deficiency ◽  
Calcareous Soils ◽  
Phosphorus Nutrition ◽  
Shoot Biomass ◽  
Phosphorus Concentration ◽  
Available Phosphorus ◽  
Nitrogen Concentrations ◽  
One Year ◽  
Index Ratio

Relation between wheat (Triticum aestivum) nutritional status determined at the beginning of stem elongation and during anthesis, respectively, and available content of phosphorus (P-M3) and zinc (Zn-M3) determined by the Mehlich 3 extractant was studied. Both one-year pot experiment with spring wheat and two-year on-farm trials with winter wheat were run on various calcareous soils (pH values of 7.18–7.94, median 7.80, P-M3 1–289 ppm, median 54, and Zn-M3 2–14 ppm, median 4), in the Czech Republic (Central Europe). Phosphorus nutrition index (ratio of phosphorus concentration in shoot biomass to critical phosphorus concentration – P<sub>c</sub>) was calculated using the Belanger et al.’s model: P<sub>c</sub> = –0.677 + 0.221N – 0.00292N(2), where both phosphorus and nitrogen concentrations were expressed in g/kg shoot dry matter. Unlike phosphorus concentration in shoot biomass, phosphorus nutrition index significantly correlated with P-M3 content in soil. Optimal values of the phosphorus nutrition index were recorded if P-M3 was 51–68 ppm. Zinc concentration in shoot biomass more strongly correlated with P:Zn ratio (M3) in soil compared to Zn-M3 content in soil. P:Zn ratio in shoot biomass of 130:1 did not lead to phosphorus deficiency and corresponded to P:Zn (M3) ratio in soil of 9.3:1–14.3:1.

Dietary cholecalciferol lowers the maximal activity of intestinal mucosa phytase in ducklings fed low-phosphorus diets

2011 ◽  
Vol 91 (3) ◽  
pp. 399-404
Author(s):  
E. M. Onyango ◽  
O. Adeola
Keyword(s):  
Total Phosphorus ◽  
Intestinal Mucosa ◽  
Maximal Activity ◽  
Phosphorus Concentration ◽  
Available Phosphorus ◽  
Total Phosphorus Concentration ◽  
Ileal Digestibility ◽  
Low Phosphorus ◽  
The Individual

Onyango, E. M. and Adeola, O. 2011. Dietary cholecalciferol lowers the maximal activity of intestinal mucosa phytase in ducklings fed low-phosphorus diets. Can. J. Anim. Sci. 91: 399–404. The role of cholecalciferol and phosphorus in the regulation of intestinal mucosa phytase was investigated in White Pekin ducklings. Ninety-six 7-d-old male ducklings were grouped by weight into six blocks of four cages with four ducklings per cage. The average weights of the individual birds in the six subgroups were: 282, 270, 263, 255, 247 and 236 g, respectively. Four corn-soybean meal-based mash diets were randomly assigned to cages within each block. The four diets consisted of cholecalciferol at 0 or 75 µg kg–1 and total phosphorus at 3.6 or 7.0 (or 0.12 or 0.46 available phosphorus, respectively) g kg−1 in a 2×2 factorial arrangement. Birds were fed the experimental diets for 9 d under conditions that excluded ultraviolet light. Ducklings fed diets with cholecalciferol concentration at 75 µg kg−1 of diet showed a lower maximal activity and Km value of intestinal mucosa phytase (P<0.05), and higher apparent ileal digestibility of calcium (P<0.0001). Ducklings fed diets with total phosphorus concentration at 7.0 g kg−1 of diet showed no change in intestinal mucosa phytase activity, but had higher weight gain, feed intake, tibia ash, ileal digestibility of phosphorus (P<0.0001), and feed efficiency (P<0.001). In conclusion, dietary cholecalciferol decreased the maximal activity and Km value of intestinal mucosa phytase in ducklings fed low-phosphorus diets.

The effect of anaerobic zone mixing on the performance of a three-stage Bardenpho plant

1998 ◽  
Vol 38 (1) ◽  
pp. 55-62 ◽  
Author(s):  
S. C. Williams ◽  
J. Beresford
Keyword(s):  
Detrimental Effect ◽  
Flow Characteristic ◽  
Tracer Tests ◽  
Poor Performance ◽  
Phosphorus Concentration ◽  
Effluent Quality ◽  
Mixing Energy ◽  
The United Kingdom ◽  
Low Phosphorus ◽  
Anaerobic Zone

Thames Water have built a three-stage Bardenpho activated sludge plant to treat 50% of the wastewater flow at Slough in the United Kingdom. Following commissioning, the plant performed well in terms of nitrification and denitrification but did not produce an effluent with a low phosphorus concentration. One possible explanation for the poor performance was the mixing of the anaerobic zone. The flow characteristic of the anaerobic zone was identified by tracer tests and alternative mixing regimes were tested. The results showed that reducing the mixing energy in the anaerobic zone had no detrimental effect on the effluent quality. The plant has operated with the reduced mixing input for nine months and the effluent phosphorus concentration has been reduced from 2.1 mgl−1 to 0.8 mgl−1.

scholarly journals What Is the Metabolic Amplification of Insulin Secretion and Is It (Still) Relevant?

Metabolites ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 355
Author(s):  
Ingo Rustenbeck ◽  
Torben Schulze ◽  
Mai Morsi ◽  
Mohammed Alshafei ◽  
Uwe Panten
Keyword(s):  
Insulin Secretion ◽  
Beta Cell ◽  
Adenine Nucleotides ◽  
Pancreatic Beta Cell ◽  
Secretory Response ◽  
Mitochondrial Activity ◽  
Insulin Synthesis ◽  
Sequence Of Events ◽  
Insulin Granules

The pancreatic beta-cell transduces the availability of nutrients into the secretion of insulin. While this process is extensively modified by hormones and neurotransmitters, it is the availability of nutrients, above all glucose, which sets the process of insulin synthesis and secretion in motion. The central role of the mitochondria in this process was identified decades ago, but how changes in mitochondrial activity are coupled to the exocytosis of insulin granules is still incompletely understood. The identification of ATP-sensitive K+-channels provided the link between the level of adenine nucleotides and the electrical activity of the beta cell, but the depolarization-induced Ca2+-influx into the beta cells, although necessary for stimulated secretion, is not sufficient to generate the secretion pattern as produced by glucose and other nutrient secretagogues. The metabolic amplification of insulin secretion is thus the sequence of events that enables the secretory response to a nutrient secretagogue to exceed the secretory response to a purely depolarizing stimulus and is thus of prime importance. Since the cataplerotic export of mitochondrial metabolites is involved in this signaling, an orienting overview on the topic of nutrient secretagogues beyond glucose is included. Their judicious use may help to define better the nature of the signals and their mechanism of action.

Peripheral muscarinic control of norepinephrine release in the cardiovascular system

1980 ◽  
Vol 239 (6) ◽  
pp. H713-H720 ◽  
Author(s):  
E. Muscholl
Keyword(s):  
Physiological Role ◽  
Sympathetic Nerves ◽  
Adrenergic Nerve ◽  
Sequence Of Events ◽  
Adrenergic Response ◽  
Adrenergic Nerve Terminals ◽  
Muscarinic Cholinergic ◽  
Related Compounds ◽  
Stimulation Of

Activation of muscarinic cholinergic receptors located at the terminal adrenergic nerve fiber inhibits the process of exocytotic norepinephrine (NE) release. This neuromodulatory effect of acetylcholine and related compounds has been discovered as a pharmacological phenomenon. Subsequently, evidence for a physiological role of the presynaptic muscarinic inhibition was obtained on organs known to be innervated by the autonomic ground plexus (Hillarp, Acta. Physiol. Scand. 46, Suppl. 157: 1-68, 1959) in which terminal adrenergic and cholinergic axons run side by side. Thus, in the heart electrical vagal stimulation inhibits the release of NE evoked by stimulation of sympathetic nerves, and this is reflected by a corresponding decrease in the postsynaptic adrenergic response. On the other hand, muscarinic antagonists such as atropine enhance the NE release evoked by field stimulation of tissues innervated by the autonomic ground plexus. The presynaptic muscarine receptor of adrenergic nerve terminals probably restricts the influx of calcium ions that triggers the release of NE. However, the sequence of events between recognition of the muscarinic compound by the receptor and the process of exocytosis still remains to be clarified.

Exhibition 58: Modern Architecture in England, Museum of Modern Art, 1937

2013 ◽  
Vol 56 ◽  
pp. 277-298 ◽  
Author(s):  
Alan Powers
Keyword(s):  
New York ◽  
Modern Art ◽  
Modern Architecture ◽  
Museum Of Modern Art ◽  
Multiple Sequence ◽  
Sequence Of Events ◽  
The World ◽  
The Usa ◽  
New Yorkers

Exhibition 58: Modern Architecture in England, held between 10 February and 7 March 1937 at the Museum of Modern Art in New York (MoMA), was a notable event. Amidst claims that ‘England leads the world in modern architectural activity’, the exhibition ‘amazed New Yorkers’ and equally surprised English commentators. However, it has not subsequently received any extended investigation. The present purpose is to look at it as a multiple sequence of events, involving other exhibitions, associated publications and the trajectories of individuals and institutions, through which tensions came to the surface about the definition and direction of Modernism in England and elsewhere. Such an analysis throws new light on issues such as the motives for staging the exhibition, the personnel involved and associated questions relating to the role of émigré architects in Britain and the USA, some of which have been misinterpreted in recent commentaries.Hitchcock's unequivocal claim for the importance of English Modernism at this point still arouses disbelief, and raises a question whether it can be accepted at face value or requires explaining in terms of some other hidden intention.

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