Phosphorus Deficiency and its Variation among Lakes

1990 ◽  
Vol 47 (6) ◽  
pp. 1077-1084 ◽  
Author(s):  
David J. Currie
Keyword(s):  
United States ◽  
Seasonal Variation ◽  
Water Chemistry ◽  
Rate Constant ◽  
Seasonal Variability ◽  
Bacterial Abundance ◽  
Phosphorus Deficiency ◽  
Northeastern United States ◽  
P Deficiency ◽  
P Concentration

The severity of phosphorus deficiency varies greatly among lakes. Is this variation related to particular morphological, chemical, or biological characteristics of lakes? These questions were addressed by sampling 49 lakes in Quebec, Ontario, and the northeastern United States. The rate constant of orthophosphate uptake (k1), a measure of orthophosphate demand:supply, proved to be only weakly related to watershed area and to the total phosphorus (P) concentration of the water (R2 = 0.210). Abundance of the biota and other aspects of water chemistry were all unrelated to the intensity of P-deficiency as it varies among lakes. In contrast, within-lake seasonal variability of the rate constant of orthophosphate turnover (kt, which is approximately equal to k1) is strongly related to temperature and bacterial abundance (R2 = 0.575 to 0.828). The results indicate that the seasonal variation in phosphorus deficiency depends strongly on bacterioplankton activity, whereas inter-lake variability in phosphorus deficiency is determined mainly by factors other than morphometry, plankton abundance, or trophic richness.

Phosphate Uptake by Spirodela and Lemna during Early Phosphorus Deficiency

1987 ◽  
Vol 14 (5) ◽  
pp. 561
Author(s):  
I.R McPharlin ◽  
R.L Bieleski
Keyword(s):  
Phosphorus Deficiency ◽  
Fold Increase ◽  
P Fractions ◽  
P Deficiency ◽  
First Order ◽  
Phosphate Ion ◽  
P Concentration ◽  
Uptake Rates ◽  
Spirodela Oligorrhiza

Growth, internal P concentration and Pi uptake was investigated in sterile cultures of Spirodela oligorrhiza (Kurz) Hegelm. and Lemna major L. plants during early P-deficiency. Within 12 h of transfer to a P-deficient medium, Pi uptake rates by P-deficient (- P) plants were enhanced 30-120% compared with P adequate (+ P) controls at 1-1000 �M external [Pi]. The enhancement in Pi uptake rates with P-deficiency normally preceded, and was more pronounced than, other effects of P-deficiency such as reduced growth, reduced internal [P] and appearance of visual symptoms. Enhanced Pi uptake rates in - P compared with +P plants resupplied with Pi was more closely correlated with a fall in the internal [Pi] (r = -0.93 to -0.98) than with a fall in the concentration of three other P fractions (i.e. ester P, lipid P, and residual P). The role of tissue [Pi] in Spirodela and Lemna plants as a possible determinant of Pi uptake rates is discussed. Kinetic analysis showed that enhanced Pi uptake in -P compared with + P plants resupplied with Pi was the result of a 2-4-fold increase in V*max of two first- order systems and not by an increased affinity (i.e. reduced K*m) of the carrier for the phosphate ion.

scholarly journals Monopotassium phosphate (KH2PO4) and salicylic acid (SA) as seed priming in Vicia faba L. and Vicia sativa L.

2020 ◽  
Vol 36 (6) ◽  
Author(s):  
Wissal M'Sehli ◽  
Nadia Kallala ◽  
Karima Jaleli ◽  
Amal Bouallegue ◽  
Haythem Mhadhbi
Keyword(s):  
Vicia Faba ◽  
Seedling Establishment ◽  
Plant Biomass ◽  
Phosphorus Deficiency ◽  
Seed Priming ◽  
Vicia Sativa ◽  
P Deficiency ◽  
Exogenous Application ◽  
P Concentration ◽  
The Impact

The first experiment was conducted to evaluate the impact of seed priming on germination behavior and seedling establishment in Vicia faba and Vicia sativa, for that, seeds priming was done using SA (100 µM) and KH2PO4. In order to determine the optimal concentration of KH2PO4 for improving germination, different concentrations were used: 25 µM, 50 µM, and 100 µM. The best germination behavior and seedling establishment were obtained with 25 and 50 µM KH2PO4, respectively for Vicia faba and Vicia sativa. Moreover, data showed that 100 µM of SA improved seed germination as well as the seedling establishment for both species. The second experiment was carried out to investigate the influence of seed priming for improving phosphorous (P) deficiency tolerance. To do, seedling obtained from primed and nonprimed seeds were grown in a hydroponic culture system with three different treatments: control (C, medium containing sufficient P concentration: 360 µM KH2PO4), direct phosphorus-deficient (DD, medium containing only 10 µM KH2PO4), and induced P deficiency by bicarbonate (ID, medium containing sufficient P concentration: 360 µM KH2PO4 + 0.5 g L-1 CaCO3 + 10 mM NaHCO3). Furthermore, the role of exogenous SA applied to P deficiency tolerance enhancement was explored. Seed priming or the exogenous application of SA significantly reduced the severity effect of P deficiency. In fact, the pretreated plants were observed more tolerant to P deficiency as reflected from the significant increase in plant biomass, P uptake, and an efficient antioxidant system. Overall, this paper highlights the beneficial effect of seeds priming or the exogenous application of SA in the improvement of plant tolerance to phosphorus deficiency.

scholarly journals Blood Phosphorus Concentration as an Indicator of Phosphorus Deficiency in Growing Cattle

Proceedings ◽  
2020 ◽  
Vol 36 (1) ◽  
pp. 136
Author(s):  
Rob Dixon ◽  
Stephen Anderson ◽  
Lisa Kidd ◽  
Mary Fletcher
Keyword(s):  
Diet Quality ◽  
Rainy Season ◽  
Phosphorus Deficiency ◽  
Cattle Grazing ◽  
Phosphorus Concentration ◽  
Threshold Values ◽  
P Deficiency ◽  
Inorganic P ◽  
P Concentration ◽  
Young Cattle

Inadequate intakes of phosphorus (P) by cattle can cause P deficiency and severely reduce productivity. Blood inorganic P concentration (Pi) is often used as an indicator of P deficiency. Results from two experiments (E1 and E2) with young cattle grazing tropical P-deficient rainy season pastures without or with additional P, or fed in pens on higher energy pelleted diets ranging in P concentration (E3), were used to examine the relationships between Pi and liveweight (LW) gain. When Pi was >2.0 mmol/L average LW gains were 0.71, 0.85 and 1.04 kg/day in E1, E2 and E3, respectively. These differences between experiments were most likely associated with diet limitations other than P. LW gain was related curvilinearly in E1 and E2, and linearly in E3, with Pi. The Pi ranged from ca. 1.0 mmol/L through to 2.5–3.0 mmol/L in each experiment. The reductions in LW gains from the maximum at Pi > 2.0 mmol/L for several lower Pi concentrations were calculated from these relationships. At Pi = 1.0 mmol/L the LW gains were 36–60% of the maximum, at Pi = 1.5 mmol/L LW gains were 59–84% of the maximum, and at Pi = 2.0 mmol/L the LW gains were 82–98% of the maximum. The reductions in LW gain at each Pi were substantially greater for E3 than for E1 and E2. It is concluded that the Pi threshold indicative of P deficiency varies with the diet quality and that the threshold values are substantially higher with higher diet quality.

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