N2 fixation in a young Alnus incana stand, based on seasonal and diurnal variation in whole plant nitrogenase activity

1992 ◽  
Vol 70 (8) ◽  
pp. 1537-1544 ◽  
Author(s):  
Kerstin Huss-Danell ◽  
Per-Olof Lundquist ◽  
Helene Ohlsson
Keyword(s):  
Seasonal Variation ◽  
Diurnal Variation ◽  
Nitrogenase Activity ◽  
Molar Ratio ◽  
Hydrogenase Activity ◽  
Alnus Incana ◽  
Growing Seasons ◽  
Leaf Emergence ◽  
Activity Measurements ◽  
Acetylene Reducing Activity

N2 fixation by grey alder, Alnus incana (L.) Moench, was studied in the field during two growing seasons in northern Sweden. Alders were planted in a nitrogen-poor soil. Each alder had its root system enclosed in an open-ended cylinder that was closed with a gas-tight lid around the stem base to serve as cuvette during nitrogenase activity (acetylene reducing activity) measurements. To follow the seasonal variation, nitrogenase activity was measured at noon on 15 occasions for each alder in 1987 and on 15 occasions in 1988. Diurnal variation in nitrogenase activity was studied at six occasions, but no obvious pattern in the diurnal variation was found. Nitrogenase activity began shortly after leaf emergence at the very end of May, increased in June, stayed high although with some variation through July and August, declined during September, and was zero in early October. Cumulative nitrogenase activity over the season was converted to cumulative N2 fixation after determination of molar ratio nitrogenase activity to N2 fixation. This conversion was facilitated as the Frankia chosen as symbiont was lacking hydrogenase activity. Control experiments showed that the introduced symbiont was the only infective Frankia in the soil. N2 fixation was estimated to be 0.23 and 2.83 g N/(alder∙year) in the 1st and 2nd year, respectively. Despite its young age, A. incana was apparently capable of high N2 fixation rates at the high latitude studied. Key words: Alnus incana, hydrogenase, intact plants, N2 fixation, seasonal variation, spreading of Frankia.

scholarly journals Factors affecting nitrogenase activity (C2H2 reduction) associated with sorghum and millet estimated using the soil core assay

1983 ◽  
Vol 29 (8) ◽  
pp. 1063-1069 ◽  
Author(s):  
S. P. Wani ◽  
P. J. Dart ◽  
M. N. Upadhyaya
Keyword(s):  
Soil Moisture ◽  
Seasonal Variation ◽  
Moisture Content ◽  
Soil Temperature ◽  
Diurnal Variation ◽  
Host Plant ◽  
Soil Moisture Content ◽  
Nitrogenase Activity ◽  
Soil Core ◽  
Factors Affecting

Factors affecting nitrogenase activity associated with sorghum and millet roots have been studied. Plants grown in iron cores in the field and then assayed had significantly higher activity than plants cored at the time of assay. Mechanical disturbance during transportation of the cores reduced the activity significantly. Any delay between cutting off the plant top and injecting C2H2 gas led to a reduction in the level of nitrogenase activity determined. Diurnal variation in nitrogenase activity was noted but was not correlated with soil temperature. Most activity occurred at the end of the photoperiod. Seasonal variation in nitrogenase activity of plants was observed and was correlated with the ontogenetic development of the host plant, being most at flowering. A low but significant correlation existed between soil moisture content and nitrogenase activity associated with the plant.

Seasonal and diurnal variation of nitrogenase activity (acetylene reduction) in barrel medic (Medicago truncatula Gaertn.) grown in pots

1978 ◽  
Vol 29 (5) ◽  
pp. 951 ◽  
Author(s):  
JJ Ruegg ◽  
AM Alston
Keyword(s):  
Nitrogen Fixation ◽  
Diurnal Variation ◽  
Medicago Truncatula ◽  
Acetylene Reduction ◽  
Time Course ◽  
Nitrogenase Activity ◽  
Seasonal Pattern ◽  
Molar Ratio ◽  
Multiple Use ◽  
Seasonal And Diurnal Variation

Seasonal and diurnal variation of nitrogenase activity in Medicago truncatula Gaertn. was measured by means of the acetylene reduction assay on plants grown in pots. In a glasshouse set at 20°C, the seasonal pattern of acetylene reduction (AR) activity was closely correlated with dry weight and photosynthetic area. Short-term fluctuations in AR activity were mainly associated with irradiance. Measurements made of the diurnal variation of AR activity showed that rates of AR at noon were 10–60% (average 33%) higher than the mean daily rates. Effects of defoliation and shading gave further evidence for the importance of light and recent photosynthate for nitrogen fixation in root nodules of legumes. Values for acetylene reduction integrated over time were highly correlated with the total amount of nitrogen in the plant. The molar ratio of acetylene reduced to nitrogen accumulated by the plants at the end of the experiment was 1.2 : 1. The significance of this value is discussed. Multiple use of the same plant material to study the time course of nitrogen fixation by the AR assay was found to be feasible under certain conditions.

Seasonal variation in the nutrient composition of the foliage of pecan (Carya illinoensis)

1986 ◽  
Vol 26 (3) ◽  
pp. 393 ◽  
Author(s):  
GC Cresswell ◽  
RJ Wickson
Keyword(s):  
Seasonal Variation ◽  
New South ◽  
Seasonal Pattern ◽  
Nutrient Status ◽  
Growing Seasons ◽  
Leaf Emergence ◽  
South Wales ◽  
Calcium Magnesium ◽  
Phosphorus And Potassium ◽  
Nitrogen Phosphorus

Leaves were sampled every 2 weeks throughout the 1980-81 and 1981-82 growing seasons from a commercial pecan orchard in New South Wales. Leaf concentrations of nitrogen, phosphorus and potassium were highest at leaf emergence and decreased with time. Concentrations of calcium, magnesium and boron were lowest early in the season and increased with time. There was no true seasonal pattern in leaf zinc which varied in apparent response to foliar zinc spray use. These trends were similar for the cultivars Witchita and Western Schley. Minimum seasonal variation in nitrogen, phosphorus, and potassium, the main fertiliser nutrients, occurred between 1 February and 21 March. This period is therefore the most suitable for general diagnostic purposes such as the evaluation of fertiliser programs and surveys of crop nutrient status.

Distribution of biomass and nitrogen among plant parts and soil nitrogen in a young Alnus incana stand

1992 ◽  
Vol 70 (8) ◽  
pp. 1545-1549 ◽  
Author(s):  
Kerstin Huss-Danell ◽  
Helene Ohlsson
Keyword(s):  
Leaf Litter ◽  
Nitrogenase Activity ◽  
Final Height ◽  
Belowground Biomass ◽  
Dry Mass ◽  
Local Source ◽  
Alnus Incana ◽  
Soil N ◽  
Plant Parts ◽  
Activity Measurements

Grey alder, Alnus incana (L.) Moench, was inoculated with the local source of Frankia and planted in nitrogen-poor soil in northern (63.8°N, 20.3°E) Sweden. Each alder root system was enclosed in a cylinder that served as an open-ended cuvette for nitrogenase activity measurements. The alders grew well, especially during the 2nd year of the study. The final leaf area in each season was more closely related to total alder biomass than final height of alders. The alders lost 17% of their total dry mass as leaf litter each year. This corresponded to 33 g dry mass and 0.67 g N per alder during the 2nd year. During the 2 years the soil N increment was 0.52 g N per alder. Leaf litter N and the increase in soil N corresponded to 27 and 17%, respectively, of the N2 fixed in the 2 years. Already at a young age, N2-fixing A. incana can apparently contribute to an improved fertility of N deficient soils. Key words: aboveground biomass, Alnus incana, belowground biomass, leaf litter, nitrogen content, soil N increment.

A New Method for Plasminogen Standardization

1968 ◽  
Vol 20 (03/04) ◽  
pp. 548-554
Author(s):  
J Gajewski ◽  
G Markus
Keyword(s):  
Proteolytic Activity ◽  
Specific Activity ◽  
Molar Ratio ◽  
Sharp Transition ◽  
Equivalence Point ◽  
Constant Amount ◽  
Residual Level ◽  
Activity Measurements ◽  
Complete Saturation ◽  
Human Plasminogen

SummaryA method for the standardization of human plasminogen is proposed, based on the stoichiometric interaction between plasminogen and streptokinase, resulting in inhibition of proteolytic activity. Activation of a constant amount of plasminogen with increasing amounts of streptokinase yields linearly decreasing activities, as a function of streptokinase, with a sharp transition to a constant residual level. The point of transition corresponds to complete saturation of plasmin with streptokinase in a 1:1 molar ratio, and is therefore a measure of the amount of plasminogen present initially, in terms of streptokinase equivalents. The equivalence point is independent of the kind of protein substrate used, buffer, pH, length of digestion and, within limits, temperature. The method, therefore, is not subject to the variations commonly encountered in the usual determination based on specific activity measurements.

Estimating Nitrogenase Activity of Faba Bean (Vicia faba) by Acetylene Reduction (Ar) Assay

1990 ◽  
Vol 17 (5) ◽  
pp. 489 ◽  
Author(s):  
Herdina ◽  
JH Silsbury
Keyword(s):  
Diurnal Variation ◽  
Vicia Faba ◽  
Faba Bean ◽  
Closed System ◽  
N2 Fixation ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Electron Flow ◽  
Specific Rate ◽  
Rooting Medium

Methods of conducting acetylene reduction (AR) assay were appraised for estimating the nitrogenase activity of nodules of faba bean (Vicia faba L.). Factors considered were: (i) disturbance of plants when removing the rooting medium; (ii) assay temperature; (iii) the use of whole plants rather than detached, nodulated roots; (iv) diurnal variation in nodule activity; and (v) a decline in C2H4 production after exposure to C2H2. Plants growing in jars of 'oil dry' (calcined clay) had the same AR activity when assayed in situ in a closed system as when assayed after removal of the rooting medium. Assay temperatures of 12.5, 17.5 and 22.5°C influenced the specific rate of AR with the optimum at 17.5°C. Removal of the shoot resulted in a rapid decrease in AR activity in both vegetative and reproductive plants but the effect was much larger in the latter. AR and respiration by nodulated roots were closely linked and both varied markedly over a diurnal 12 h/12 h cycle. Since no fluctuation was found after nodules were detached, diurnal variation in the respiration of nodulated roots is attributed to change in nodule activity. Half of the dark respiration of nodulated roots was associated with respiration of the nodules and thus largely with N2 fixation. Since the AR assay provides no information on how electron flow in vivo is partitioned between reduction of N2 and reduction of protons, diurnal variation in hydrogen evolution (HE) in air and Ar/O2 in an open system was used to estimate this partitioning. Diurnal variation in apparent N2 fixation estimated in this manner was examined at a 'low' PPFD (300 μmol m-2 s-1) and at 'high' (1300 μmol m-2 s-1) to explore whether variation could be attributed to change in carbohydrate supply. Although HE in air and in Ar/O2 were both closely linked with the respiration of the nodulated root, apparent N2 fixation showed only a slight diurnal variation at 'low' light and almost none at 'high'. Vegetative plants showed no C2H2-induced decline in activity with exposure to C2H2 but reproductive plants did. This difference appears to be an age effect rather than attributable to flowering per se, since a decline occurred even when plants were kept vegetative by disbudding. A closed system for AR assay appears satisfactory for vegetative faba bean but such an assay over a 40-min period during the reproductive stage would underestimate nitrogenase activity by about 20%.

Dinitrogen fixation and nodulation by Frankia in Alnus incana as affected by inorganic nitrogen in pot experiments with peat

1983 ◽  
Vol 61 (11) ◽  
pp. 2956-2963 ◽  
Author(s):  
U. Granhall ◽  
T. Ericsson ◽  
M. Clarholm
Keyword(s):  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Inorganic Nitrogen ◽  
Experimental Period ◽  
Alnus Incana ◽  
Nitrogen Application ◽  
Noticeable Effect ◽  
Essential Nutrients ◽  
Pot Experiments ◽  
Ph Level

The effects of single large or repeated, exponentially increasing applications of nutrients, with or without inorganic nitrogen and at two pH levels, on the growth, nodulation, acetylene reduction, and nutrient uptake in Alnus incana (L.) Moench were investigated in pot experiments with peat under controlled laboratory conditions. The repeated application of inorganic nitrogen did not suppress nitrogenase activity until the last 2 weeks, whereas an initial, large, nitrogen application effectively inhibited nodulation and activity throughout the 40-day experimental period. The mode of nitrogen application was thus found to be more important than the total amounts applied. Shoot length, leaf area, shoot–root relations, dry-matter production, and nitrogen contents of plants were determined at the end of the experiment, as well as the effect of Frankia inoculations. Nitrogenase activity was determined three times, at 0, 3, and 5 weeks. N2 fixation (balance/acetylene reduction) was found to be maximal, 55% of total nitrogen uptake, in minus-N pots with single applications of essential nutrients. The fastest growth was, however, noted in pots with single applications of all nutrients, including N. Among the latter, pots inoculated with Frankia showed the best growth, in spite of low nitrogenase activity. The only noticeable effect of a raised pH level was a reduced endophyte activity in minus-N pots with single applications of essential nutrients, due to increased N mineralization in the peat.

scholarly journals Observed and predicted characteristics of equatorial F1 layer during solar minimum

2014 ◽  
Vol 32 (5) ◽  
pp. 571-580 ◽  
Author(s):  
C.-C. Lee
Keyword(s):  
Seasonal Variation ◽  
Diurnal Variation ◽  
Solar Minimum ◽  
Shape Parameter ◽  
Early Morning ◽  
Peak Height ◽  
Time Range ◽  
Occurrence Probability ◽  
Peak Density

Abstract. This study aims to assess the predictability of IRI-2012 on the equatorial F1 layer during solar minimum. The observed characteristics of F1 layer by the Jicamarca digisonde are compared with the model outputs. The results show that the time range for F1-layer appearance of observation is longer than that of IRI-2012, by at least 1 h in the early morning and later afternoon. In IRI-2012, there are three options for the occurrence probability of F1 layer: IRI-95, Scotto-97 no L, and Scotto-97 with L options. The first option predicts the probability well, but the last two underestimate the probability. The peak density of F1 layer (NmF1) of observation is very close to that of IRI-2012. For the F1 peak height (hmF1), the modeled values are smaller than the observed ones. The observed seasonal variation of hmF1 is not found in the modeled results. Nevertheless, the observed diurnal variation of hmF1 is similar to the modeled results with the B0 choices of Bil-2000 and ABT-2009. Regarding the shape parameter, the values of D1 (the shape parameter of F1 layer in observation) are much greater than the values of C1 (the shape parameter of F1 layer in IRI-2012). The D1 values are 3–6 times the C1 values. The diurnal variation of D1 is similar to that of C1, but the seasonal variation of D1 is not.

Nitrogen fixation (acetylene reduction) by Klebsiella pneumoniae in association with 'Park' Kentucky bluegrass (Poa pratensis L.)

1981 ◽  
Vol 27 (1) ◽  
pp. 52-56 ◽  
Author(s):  
L. V. Wood ◽  
R. V. Klucas ◽  
R. C. Shearman
Keyword(s):  
Nitrogen Fixation ◽  
Klebsiella Pneumoniae ◽  
Ethylene Production ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Poa Pratensis ◽  
Kentucky Bluegrass ◽  
Surface Sterilization ◽  
Reducing Activity ◽  
Acetylene Reducing Activity

Turfs of 'Park' Kentucky bluegrass reestablished in the greenhouse and inoculated with Klebsiella pneumoniae (W6) showed significantly increased nitrogen fixation (acetylene reduction) compared with control turfs. Mean ethylene production rates per pot were 368 nmol h−1 for K. pneumoniae treated turfs, 55 nmol h−1 for heat-killed K. pneumoniae treated turfs, and 44 nmol h−1 for untreated turfs. Calculated lag periods before activity was observed were generally very short (less than 1 h).When 'Park' Kentucky bluegrass was grown from seed on soil-less medium of Turface, a fired aggregate clay, inoculation with K. pneumoniae (W6) resulted in 9 of 11 turfs showing nitrogenase activity (mean ethylene producion rate per pot was 195 nmol h−1). Only 3 of 11 turfs treated with heat-killed K. pneumoniae showed any activity and their mean rate of ethylene production (40 nmol h−1 per pot) was significantly lower than that for turfs treated with K. pneumoniae.Using the 'Park'–Turface soil-less model system it was shown that acetylene reducing activity was (i) root associated, (ii) generally highest at a depth of 1–4 cm below the surface, (iii) enhanced by washing excised roots, and (iv) inhibited by surface sterilization of excised roots. Klebsiella pneumoniae was recovered from Turface and roots showing acetylene reducing activity.

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