Nitrogen source effects on Al toxicity in nonmycorrhizal and mycorrhizal pitch pine (Pinus rigida) seedlings. I. Growth and nutrition

1990 ◽  
Vol 68 (12) ◽  
pp. 2644-2652 ◽  
Author(s):  
Jonathan R. Cumming ◽  
Leonard H. Weinstein
Keyword(s):  
Nitrogen Source ◽  
Critical Factor ◽  
Aluminium Toxicity ◽  
Ectomycorrhizal Fungus ◽  
Al Toxicity ◽  
Sand Culture ◽  
P Availability ◽  
Pinus Rigida ◽  
P Limitation ◽  
Pitch Pine

Previous studies indicated that the association of Pisolithus tinctorius with pitch pine (Pinus rigida) seedling roots prevented Al toxicity from developing when seedlings were exposed to 200 μM Al in sand culture. The ectomycorrhizal fungus reduced seedling Al uptake and maintained P nutrition when seedlings were cultured on one-quarter strength Johnson's solution containing 3.5 and 0.5 mM [Formula: see text] and [Formula: see text], respectively. To broaden the scope of these findings, nonmycorrhizal and mycorrhizal seedlings were grown on one-quarter strength Johnson's solution modified to contain [Formula: see text], NH4NO3, or [Formula: see text]. Seedlings were exposed to 0 or 200 μM Al for 6 weeks. Reductions in seedling height growth rate and final shoot weight in response to Al occurred in nonmycorrhizal seedlings grown with [Formula: see text]. Root weights were consistently reduced by Al under all N-source combinations. Increasing proportions of [Formula: see text], in the nutrient solution increased cation accumulation in roots and shoots and depressed tissue anion concentrations. The coprecipitation of Al and Pi in roots of Al-treated seedlings further limited P availability in this treatment. Mycorrhizal infection maintained growth and foliar P levels under Al exposure, suggesting that Al-induced P limitation was a critical factor in nonmycorrhizal seedlings grown on primarily [Formula: see text]-based nutrient solutions. Key words: Pinus rigida, ectomycorrhizal, aluminium toxicity, nitrogen source.

Nitrogen source effects on Al toxicity in nonmycorrhizal and mycorrhizal pitch pine (Pinus rigida) seedlings. II. Nitrate reduction and NO3− uptake

1990 ◽  
Vol 68 (12) ◽  
pp. 2653-2659 ◽  
Author(s):  
Jonathan R. Cumming
Keyword(s):  
Nitrogen Source ◽  
Nitrate Reduction ◽  
Al Toxicity ◽  
Pisolithus Tinctorius ◽  
Sand Culture ◽  
Root Tips ◽  
Pinus Rigida ◽  
Pine Seedlings ◽  
Pitch Pine ◽  
Nr Activity

Nitrogen source utilization, mediated by the ectomycorrhizal symbiont Pisolithus tinctorius, may modulate Al toxicity in pitch pine (Pinus rigida) seedlings. Nitrate reduction, occurring primarily in the roots of pitch pine seedlings, represents a critical metabolic pathway that may be directly sensitive to Al or indirectly affected by changes in NO3− availability associated with Al exposure or mycorrhizal infection. To investigate these possibilities, pitch pine seedlings were grown in sand culture with NO3−, NH4NO3, or NH4+ and exposed to 0 or 200 μM Al for 6 weeks. Foliar N concentrations, root nitrate reductase (NR) activity, and Al inhibition of NR activity were highly dependent on the proportion of NO3− of the nutrient solution. The association of Pisolithus tinctorius with seedling roots reduced both root and foliar NR activity compared with non-inoculated controls, suggesting that NO3− uptake and translocation to foliage was reduced by the symbiont. This was confirmed by using 36ClO3− to measure unidirectional plasma membrane NO3− fluxes. Mycorrhizal root tips absorbed 50% less NO3− than nonmycorrhizal root tips. Preferential use of NH4+ by ectomycorrhizal roots may thus result in reduced movement of Al into root tissue and amelioration of Al toxicity. Key words: Pinus rigida, ectomycorrhizae, aluminum toxicity, nitrogen source.

scholarly journals On the potential vegetation feedbacks that enhance phosphorus availability – insights from a process-based model linking geological and ecological timescales

2014 ◽  
Vol 11 (13) ◽  
pp. 3661-3683 ◽  
Author(s):  
C. Buendía ◽  
S. Arens ◽  
T. Hickler ◽  
S. I. Higgins ◽  
P. Porada ◽  
...  
Keyword(s):  
Biomass Production ◽  
Primary Productivity ◽  
Chemical Weathering ◽  
Production Efficiency ◽  
Root Exudation ◽  
Terrestrial Ecosystems ◽  
Global Scale ◽  
P Uptake ◽  
P Availability ◽  
P Limitation

Abstract. In old and heavily weathered soils, the availability of P might be so small that the primary production of plants is limited. However, plants have evolved several mechanisms to actively take up P from the soil or mine it to overcome this limitation. These mechanisms involve the active uptake of P mediated by mycorrhiza, biotic de-occlusion through root clusters, and the biotic enhancement of weathering through root exudation. The objective of this paper is to investigate how and where these processes contribute to alleviate P limitation on primary productivity. To do so, we propose a process-based model accounting for the major processes of the carbon, water, and P cycles including chemical weathering at the global scale. Implementing P limitation on biomass synthesis allows the assessment of the efficiencies of biomass production across different ecosystems. We use simulation experiments to assess the relative importance of the different uptake mechanisms to alleviate P limitation on biomass production. We find that active P uptake is an essential mechanism for sustaining P availability on long timescales, whereas biotic de-occlusion might serve as a buffer on timescales shorter than 10 000 yr. Although active P uptake is essential for reducing P losses by leaching, humid lowland soils reach P limitation after around 100 000 yr of soil evolution. Given the generalized modelling framework, our model results compare reasonably with observed or independently estimated patterns and ranges of P concentrations in soils and vegetation. Furthermore, our simulations suggest that P limitation might be an important driver of biomass production efficiency (the fraction of the gross primary productivity used for biomass growth), and that vegetation on old soils has a smaller biomass production rate when P becomes limiting. With this study, we provide a theoretical basis for investigating the responses of terrestrial ecosystems to P availability linking geological and ecological timescales under different environmental settings.

scholarly journals High Sucrose Levels and Abnormal Enzyme Activity as a Function of Nutritional Stress in Sugarcane

1969 ◽  
Vol 51 (4) ◽  
pp. 325-333
Author(s):  
Alex G. Alexander
Keyword(s):  
Nutrient Deficiency ◽  
Critical Factor ◽  
Nutritional Stress ◽  
Nutrient Supply ◽  
Oxidative Enzymes ◽  
Sand Culture ◽  
High Level ◽  
To Receive ◽  
High Sucrose ◽  
Nitrogen Phosphorus

Deficiencies of nitrogen, phosphorus, potassium, and calcium were gradually induced in sugarcane grown by sand culture. There were three objectives: 1, To determine whether nutritional stress in general is a means of inducing higher sucrose production; 2, to determine whether sucrose increases can be triggered without reaching nutrient-deficiency levels which would reduce tonnage; and 3, to ascertain whether increased sucrose production can be traced to common behavior patterns of hydrolytic and oxidative enzymes. All plants received a moderately high level of all nutrients until 14 weeks of age. Thereafter, individual nutrients were gradually lowered at intervals of 2 weeks, while control plants continued to receive the original levels. All plants subjected to nutritional stress accumulated higher leaf sucrose than control plants, regardless of the nutrient withheld. In each instance sucrose increases were recorded before nutrient supply had reached deficiency proportions. General nutritional stress thus appears to trigger variations in sugar level, with nutritional imbalance rather than actual deficiency being a critical factor. All plants under nutritional stress revealed a concurrent suppression of amylase as sucrose increased. Peroxidase was greatly stimulated by all nutritional treatments. Phosphatase was suppressed by decreasing nitrate and phosphorus, but was generally unaffected by the potassium and calcium treatments. Several distinct mechanisms of increased sucrose formation are indicated by the enzyme data. Sensitivity of amylase to changing nutrient supply is discussed from the standpoint of a possible indicator of approaching deficiency.

Nutrients in Salmonid Ecosystems: Sustaining Production and Biodiversity

2003 ◽  
Keyword(s):  
Pacific Northwest ◽  
Nutrient Release ◽  
Nutrient Status ◽  
N Availability ◽  
P Availability ◽  
Streams And Rivers ◽  
Salmon River ◽  
P Limitation ◽  
The Pacific ◽  
Simplifying Assumptions

<em>Abstract.</em>—Recent studies have shown that anadromous fish deliver ecologically significant quantities of marine-derived nitrogen (N), phosphorus (P), and organic carbon (C) to lakes, rivers, and streams of the Pacific Northwest. These marine-derived nutrients (MDN) can influence the ecological functioning of receiving streams through nutrient release and food availability. In Idaho, populations of anadromous salmon have declined dramatically with many formerly salmon-bearing streams now receiving no MDN supplementation. In order to assess how the loss of MDN may influence Idaho streams and rivers, we examined the current nutrient status of streams and rivers in Idaho with particular emphasis on the limiting role of N and P. We also generated a range of estimates of the historic and current affects of MDN on selected basins of the Salmon River, Idaho. Our analysis indicates that 25–50% of Idaho’s streams are potentially nutrient limited. Further analysis suggests that N and P limitation occurred in an approximately equal number of streams. Historic contributions of MDN to the Salmon River had varying potential to influence N and P availability, ranging from undetectable to resulting in a doubling of N availability. The level of influence depended upon location within the basin and the choices made regarding some simplifying assumptions. Finally, we discuss the effectiveness of artificial fertilization as a means of compensating for lost MDN and suggest that a spiraling approach be used to design and monitor fertilization treatments.

Characterizing Canopy Fuels to Predict Fire Behavior in Pitch Pine Stands

2007 ◽  
Vol 24 (1) ◽  
pp. 65-70 ◽  
Author(s):  
Matthew J. Duveneck ◽  
William A. Patterson
Keyword(s):  
Fire Behavior ◽  
Small Diameter ◽  
Basal Area ◽  
Regression Equations ◽  
Crown Fire ◽  
Pinus Rigida ◽  
Canopy Fuels ◽  
Pitch Pine ◽  
Thinning Operations ◽  
Pine Stands

Abstract Destructive sampling of 31 pitch pine (Pinus rigida P. Mill) trees ranging in dbh from 2.7 to 42.5 cm and in height from 4.1 to 23.8 m provided a complete inventory of needles and small-diameter branch weights used to characterize canopy fuels to predict fire behavior in pitch pine stands. Regression equations using dbh as an independent variable predict canopy bulk density with an r2 > 0.93. The results provide managers with a method of evaluating the effectiveness of thinning operations in reducing crown fire potential in well-stocked stands. To demonstrate the application of the method, we calculated the wind speed (Crowning Index [CI]) needed to sustain an active crown fire in thinned and unthinned pitch pine stands in Montague, Massachusetts. Thinning to 2.8 m2/ha basal area increased the CI from 34 to 98 km/hour.

scholarly journals Water quality, isoscapes and stoichioscapes of seagrasses indicate general P limitation and unique N cycling in shallow water benthos of Bermuda

2015 ◽  
Vol 12 (20) ◽  
pp. 6235-6249 ◽  
Author(s):  
J. W. Fourqurean ◽  
S. A. Manuel ◽  
K. A. Coates ◽  
W. J. Kenworthy ◽  
J. N. Boyer
Keyword(s):  
Water Column ◽  
Spatial Patterns ◽  
Animal Movement ◽  
P Availability ◽  
Seagrass Species ◽  
Δ13c And Δ15n ◽  
Elemental Ratios ◽  
Syringodium Filiforme ◽  
P Limitation ◽  
Near Shore

Abstract. Striking spatial patterns in stable isotope ratios (isoscapes) and elemental ratios (stoichioscapes) of seagrass leaves and the water column nutrients indicate general P-limitation of both water column and benthic primary productivity on the Bermuda Platform, and they highlight the role of the Bermuda Islands as a source of N and P. We found consistent differences among the four seagrass species (Syringodium filiforme, Thalassia testudinum, Halodule sp. and Halophila decipiens) in the N, P, δ13C and δ15N of leaf tissues. The δ15N of seagrass leaves was especially variable, with values from −10.1 to 8.8 ‰, greatly expanding the reported range of values for all seagrass species globally. Spatial patterns from both the water column and the seagrass leaves indicated that P availability was higher near shore, and δ15N values suggest this was likely a result of human waste disposal. Spatially contiguous areas of extremely depleted seagrass 15N suggest unique N sources and cycling compared to other seagrass-dominated environments. Seagrass N : P values were not as far from the stoichiometric balance between N and P availability as in the water column, and there were no strong relationships between the water column N : P and the seagrass N : P. Such isoscapes and stoichioscapes provide valuable ecogeochemical tools to infer ecosystem processes as well as provide information that can inform food web and animal movement studies.

Ecological analyses of the northernmost population of pitch pine (Pinus rigida)

1997 ◽  
Vol 27 (9) ◽  
pp. 1342-1350 ◽  
Author(s):  
A Meilleur ◽  
J Brisson ◽  
A Bouchard
Keyword(s):  
Pinus Rigida ◽  
Pitch Pine

scholarly journals Increasing P limitation and viral infection impact lipid remodeling of the picophytoplankter <i>Micromonas pusilla</i>

2016 ◽  
Vol 13 (5) ◽  
pp. 1667-1676 ◽  
Author(s):  
Douwe S. Maat ◽  
Nicole J. Bale ◽  
Ellen C. Hopmans ◽  
Jaap S. Sinninghe Damsté ◽  
Stefan Schouten ◽  
...  
Keyword(s):  
Growth Rate ◽  
Viral Infection ◽  
Lipid Composition ◽  
Lipid Membrane ◽  
Maximum Growth ◽  
P Availability ◽  
Supply Rate ◽  
P Limitation ◽  
Micromonas Pusilla ◽  
P Supply

Abstract. The intact polar lipid (IPL) composition of phytoplankton is plastic and dependent on environmental factors. Previous studies have shown that phytoplankton under low phosphorus (P) availability substitutes phosphatidylglycerols (PGs) with sulfoquinovosyldiacylglycerols (SQDGs) and digalactosyldiacylglycerols (DGDGs). However, these studies focused merely on P depletion, while phytoplankton in the natural environment often experience P limitation whereby the strength depends on the supply rate of the limiting nutrient. Here we report on the IPL composition of axenic cultures of the picophotoeukaryote Micromonas pusilla under different degrees of P limitation, i.e., P-controlled chemostats at 97 and 32 % of the maximum growth rate, and P starvation (obtained by stopping P supply to these chemostats). P-controlled cultures were also grown at elevated partial carbon dioxide pressure (pCO2) to mimic a future scenario of strengthened vertical stratification in combination with ocean acidification. Additionally, we tested the influence of viral infection for this readily infected phytoplankton host species. Results show that both SQDG : PG and DGDG : PG ratios increased with enhanced P limitation. Lipid composition was, however, not affected by enhanced (750 vs. 370 µatm) pCO2. In the P-starved virally infected cells the increase in SQDG : PG and DGDG : PG ratios was lower, whereby the extent depended on the growth rate of the host cultures before infection. The lipid membrane of the virus MpV-08T itself lacked some IPLs (e.g., monogalactosyldiacylglycerols; MGDGs) in comparison with its host. This study demonstrates that, besides P concentration, also the P supply rate, viral infection and even the history of the P supply rate can affect phytoplankton lipid composition (i.e., the non-phospholipid : phospholipid ratio), with possible consequences for the nutritional quality of phytoplankton.

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