scholarly journals (349) Fertilizer-N Effectson Cycas–Nostoc Symbiosis

HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1061A-1061
Author(s):  
Laura M. R. Rinaldi ◽  
Maria C. Margheri ◽  
Alba Ena
Keyword(s):  
Nutrient Solution ◽  
Nitrogenase Activity ◽  
Growth Cycle ◽  
N Fertilization ◽  
Fertilizer N ◽  
Reducing Activity ◽  
Acetylene Reducing Activity ◽  
Nitrogen Treatments ◽  
Indoor And Outdoor

Cycasrevoluta Thunb., cultivated as an ornamental plant for indoor and outdoor use, is characterized by an extremely slow rate of growth. In spite of the occurrence in its coralloid roots of the nitrogen-fixing cyanobiont Nostoc, N fertilization is commonly used to accelerate Cycas growth. A greenhouse experiment was conducted to examine the effects of two forms of combined N on growth of Cycas plants and cyanobacterial nitrogenase activity, measured on intact plants. Cycas plants grown in pots were fertilized from June to September with nutrient solution containing macronutrients as P, K, Mg, and Hoagland's micronutrients. N (700 mg/plant) was supplied as KNO3, or applied as NH4NO3; control plants received nutrient solution without nitrogen. Treatments were applied monthly and repeated for three times. Each treatment consisted of 15 plants. The length of the new leaves was recorded during the growth cycle of the plants. The nitrogenase activity, based on acetylene reducing activity (ARA), was measured on the plants in situ in July and in October. N fertilization stimulated both the nitrogenase activity and the growth of the plants. In comparison with the control, average increases in ARA of more than 20% were observed in the treated plants. Nitrogenase activity was slightly better in the presence of NH4NO3 in July, whereas the values measured in October were about the same for two treatments. The two forms of nitrogen were the same also regarding the stimulus on growth: in N-treated plants the total length of the new leaves was more than double with respect to the control at the end of the growing season. Control plants grown without fertilizer N had a slow start to their growth cycles and were unable to recover and compensate later for the lack of transient N.

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.

Kinetics of first-cutting regrowth of alfalfa plants and nitrogenase activity in a controlled environment with and without added nitrate

1983 ◽  
Vol 61 (9) ◽  
pp. 2405-2409 ◽  
Author(s):  
F. D. H. Macdowall
Keyword(s):  
Dry Matter ◽  
Rhizobium Meliloti ◽  
Nitrogenase Activity ◽  
Radical Change ◽  
N Nutrition ◽  
Meliloti Strain ◽  
Medicago Sativa L ◽  
Reducing Activity ◽  
Acetylene Reducing Activity ◽  
Kinetics Of

Seedlings of Medicago sativa L. cv. Algonquin were grown in vermiculite and nodulated by Rhizobium meliloti strain 102F70 at two lower levels of N, until flowering when the tops were cut off to leave about 10% shoot stubble. Residual shoot dry matter immediately resumed first-order growth and maintained it throughout regrowth to second flowering. The rate constants of shoot regrowth were 34% lower (at 15 mM NO3−), 25% lower (at 1.5 mM NO3− symbiotically), or 220% higher (at zero NO3− symbiotically) than the values for 1 to 4-week-old seedlings, which indicated a radical change in physiology. Root dry matter resumed exponential growth after a 7-day recession and its recovery and yields were independent of N nutrition. The most pronounced minima occurred in the acetylene-reducing activity of nitrogenase, the kinetics of which paralleled root dry matter except that its redevelopment stopped after two-thirds of the regrowth time. The rate coefficient for the redevelopment of nitrogenase activity equalled that for its development during the seedling stage, which suggested unchanged limitations on that process until its redevelopment stopped.

Factors affecting vesicle formation and acetylene reduction (nitrogenase activity) in Frankia sp. CpI1

1981 ◽  
Vol 27 (8) ◽  
pp. 815-823 ◽  
Author(s):  
John D. Tjepkema ◽  
William Ormerod ◽  
John G. Torrey
Keyword(s):  
Acetylene Reduction ◽  
Ethylenediaminetetraacetic Acid ◽  
Nitrogenase Activity ◽  
Carbon Sources ◽  
Vesicle Formation ◽  
Free Medium ◽  
Factors Affecting ◽  
Reducing Activity ◽  
Acetylene Reducing Activity

Vesicle formation and acetylene reduction (nitrogenase activity) were observed when washed hyphae from cultures of Frankia sp. CpI1 were transferred to a nitrogen-free medium containing ethylenediaminetetraacetic acid and succinate. Succinate could be replaced by malate or fumarate, but not other carbon sources. Maximum acetylene reduction and vesicle numbers were observed at a pH of 6.0–6.5, at 25–30 °C, and at atmospheric [Formula: see text] or somewhat less (5–20 kPa). Addition of 1 mM NH4Cl almost completely inhibited vesicle formation and acetylene-reducing activity, but did not immediately inhibit such reducing activity by cultures with preexisting vesicles. Acetylene-reducing activity was never observed in the absence of vesicle formation.

Etude de la dynamique de l'azote à haute altitude. I. Fixation d'azote (réduction de l'acétylène) par Alnus viridis

1979 ◽  
Vol 57 (19) ◽  
pp. 1979-1985 ◽  
Author(s):  
André Moiroud ◽  
André Capellano
Keyword(s):  
Reduction Method ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Cold Climate ◽  
Green Alder ◽  
Alnus Viridis ◽  
Reducing Activity ◽  
Diurnal Fluctuations ◽  
Acetylene Reducing Activity ◽  
Vegetative Season

During two vegetative seasons (1977, 1978), Alnus viridis Chaix root nodules were incubated in the field and assayed for nitrogen fixing activity by acetylene reduction method. In green alder the nitrogenase activity took place with the first opening of buds (June); maximum values were attained in July–August; the activity decreased steadily until leaf fall, and then ceased. Diurnal fluctuations in acetylene reducing activity were observed, the 1400-hour values were twice those of 1000 hours. The optimal temperature for nitrogenase activity was below 20 °C; this fact would be in relation with better adaptation of Alnus viridis to cold climate. The nodular biomass being only 40 kg/ha, the nitrogen fixed during the vegetative season (mid-June to mid-October) was only about 8 kg/ha. Symbiotic fixation accounted for only 10% of the nitrogen requirements of green alder.

Temperature sensitivity of nitrogen fixation in Azospirillum spp.

1992 ◽  
Vol 38 (12) ◽  
pp. 1238-1241 ◽  
Author(s):  
Anil K. Tripathi ◽  
Walter Klingmüller
Keyword(s):  
Nitrogen Fixation ◽  
Azospirillum Brasilense ◽  
Nitrogenase Activity ◽  
Lacz Fusion ◽  
Optimum Growth ◽  
Azospirillum Lipoferum ◽  
Reducing Activity ◽  
Acetylene Reducing Activity ◽  
The Impact ◽  
Key Words Temperature

Azospirillum brasilense and Azospirillum lipoferum showed optimum acetylene-reducing activity at 25 and 30 °C, respectively, although both the bacteria grew optimally at 35 °C. Azospirillum halopraeferens displayed optimum growth and acetylene-reducing activity at 40–41 °C. Our experiments indicated that expression of nif genes was generally more sensitive to temperature than was nitrogenase activity. The NifA-dependent activation of a heterologous nifH–lacZ fusion was used to assess the impact of temperature on native NifA activity of A. brasilense and A. lipoferum. Maximum NifA activity was observed at 25 °C in A. brasilense and at 30 °C in A. lipoferum. Key words: temperature, nitrogen fixation, nifH–lacZ fusion, NifA activity, Azospirillum.

THE EFFECT OF SEED-APPLIED PESTICIDES ON GROWTH AND N2 FIXATION IN PEA, LENTIL, AND FABABEAN

1985 ◽  
Vol 65 (1) ◽  
pp. 23-28 ◽  
Author(s):  
R. J. RENNIE ◽  
R. J. HOWARD ◽  
T. A. SWANSON ◽  
G. H. A. FLORES
Keyword(s):  
Lens Culinaris ◽  
Rhizobium Leguminosarum ◽  
Nitrogenase Activity ◽  
Wide Spectrum ◽  
Seedling Emergence ◽  
Pesticide Application ◽  
Pisum Sativum L ◽  
Vicia Faba L ◽  
Reducing Activity ◽  
Acetylene Reducing Activity

Conflicting recommendations exist on the effect of seed-applied pesticides on nodulation and N2 fixation by Rhizobium leguminosarum. This paper reports the effects of captan, thiram, metalaxyl, Evershield, DL-PLUS® and B-3 in a 2-yr field experiment on emergence, nodulation, acetylene-reducing activity, and shoot yield of pea (Pisum sativum L.), lentil (Lens culinaris L.), and fababean (Vicia faba L.) inoculated with seed-applied R. leguminosarum multi-strain inoculum. Seedling emergence was not detrimentally affected by pesticide application. While most of the pesticides had either stimulatory or minimally detrimental effects on nodulation and nitrogenase activity, captan reduced both in all three legumes. Captan-containing compounds such as B-3 (33.5% captan) and Evershield (29.5% captan) also reduced nodulation or nitrogenase activity in some of these legumes. DL-PLUS (15% captan) was not harmful, which suggests that compounds containing over 29.5% captan may not be compatible with seed-applied R. leguminosarum. Captan, which was consistently harmful, is considered the best wide-spectrum pesticide for use with these legumes. Thus, it will be necessary to select superior N2-fixing strains of R. leguminosarum that are tolerant of, if not resistant to, recommended rates of captan or to identify alternate pesticides that are more compatible with rhizobia.Key words: Captan, thiram, metalaxyl, Evershield, DL-PLUS, B-3

scholarly journals Effects of Independent and Combined Water-Deficit and High-Nitrogen Treatments on Flag Leaf Proteomes during Wheat Grain Development

2020 ◽  
Vol 21 (6) ◽  
pp. 2098 ◽  
Author(s):  
Dong Zhu ◽  
Gengrui Zhu ◽  
Zhen Zhang ◽  
Zhimin Wang ◽  
Xing Yan ◽  
...  
Keyword(s):  
Carbohydrate Metabolism ◽  
Water Deficit ◽  
Flag Leaf ◽  
Redox Homeostasis ◽  
Combined Treatment ◽  
Proteome Analysis ◽  
N Fertilization ◽  
Grain Development ◽  
High Nitrogen ◽  
Nitrogen Treatments

We present the first comprehensive proteome analysis of wheat flag leaves under water-deficit, high-nitrogen (N) fertilization, and combined treatments during grain development in the field. Physiological and agronomic trait analyses showed that leaf relative water content, total chlorophyll content, photosynthetic efficiency, and grain weight and yield were significantly reduced under water-deficit conditions, but dramatically enhanced under high-N fertilization and moderately promoted under the combined treatment. Two-dimensional electrophoresis detected 72 differentially accumulated protein (DAP) spots representing 65 unique proteins, primarily involved in photosynthesis, signal transduction, carbohydrate metabolism, redox homeostasis, stress defense, and energy metabolism. DAPs associated with photosynthesis and protein folding showed significant downregulation and upregulation in response to water-deficit and high-N treatments, respectively. The combined treatment caused a moderate upregulation of DAPs related to photosynthesis and energy and carbohydrate metabolism, suggesting that high-N fertilization can alleviate losses in yield caused by water-deficit conditions by enhancing leaf photosynthesis and grain storage compound synthesis.

Effect of heavy metals on the leaf disc ferricyanide reduction in cucumber

2009 ◽  
Vol 57 (3) ◽  
pp. 307-320
Author(s):  
G. Rabnecz ◽  
G. Záray ◽  
L. Lévai ◽  
F. Fodor
Keyword(s):  
Heavy Metals ◽  
Nutrient Solution ◽  
Chlorophyll Concentration ◽  
Leaf Disc ◽  
Transport Systems ◽  
Ferricyanide Reduction ◽  
Plasma Membrane Electron Transport ◽  
Significant Linear Correlation ◽  
Drastic Effect

The effect of heavy metals on the leaf plasma membrane electron transport systems was investigated in connection with the tissue Fe concentration in Fe-sufficient and Fe-deficient cucumber leaves. Ten M μPb in the nutrient solution inhibited leaf ferricyanide reduction by 20–26%, whereas 10 M μCd had a more drastic effect, with 80–83% inhibition. Ferricyanide reduction decreased by 14% when 1 mM Pb was applied in situ by vacuum infiltration into control leaf discs, whereas it decreased by 40% when 0.1 mM Cd was applied. Ferricyanide reduction was completely inhibited by 1 mM Cd. The ferricyanide reduction values were correlated with the heavy metal, Fe and chlorophyll concentrations in the leaves. A significant linear correlation was only found with the chlorophyll concentration. The data suggest that there are also direct effects on membranebound reductases, but these are of less significance. Using differentially Fe-deficient plants (grown with 0 to 300 nM Fe in the nutrient solution), a chlorophyll concentration of 0.9–1.0 mg g −1 fresh weight was estimated as the threshold for achieving the ferricyanide reduction levels found in the controls.

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