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.

Acetylene-induced decline in acetylene reduction by nodulated roots of alfalfa

1989 ◽  
Vol 67 (2) ◽  
pp. 360-364 ◽  
Author(s):  
F. D. H. Macdowall ◽  
G. T. Kristjansson
Keyword(s):  
Growth Temperature ◽  
Acetylene Reduction ◽  
Respiratory Activity ◽  
Rhizobium Meliloti ◽  
Continuous Treatment ◽  
Short Term ◽  
Medicago Sativa L ◽  
Reducing Activity ◽  
Acetylene Reducing Activity ◽  
Lower Temperature

Seedlings of three cultivars of alfalfa (Medicago sativa L.) were nodulated with two strains of rhizobia (Rhizobium meliloti) and grown with zero N nutrients at 25:20 °C for 6 weeks followed by growth at 10:7 °C for 2 weeks. Acetylene-reducing activity (ARA) was retarded by 10% acetylene to an extent dependent on time, cultivar, strain, and growth temperature. In the usual short term assay for nitrogenase by ARA, the inhibition was not sufficient to explain decreased apparent efficiency of nitrogenase in plants moved to the lower temperature. Inhibition of ARA was associated with correspondingly decreased respiration in cv. Drylander, but in cv. Apollo respiration was not affected. The differential loss of ARA relative to respiratory activity in a day of continuous treatment with 10% acetylene was very distinct and requires an explanation other than altered nodule resistance to diffusion of oxygen.

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.

A rapid screening method for Rhizobium meliloti symbiotic nitrogenase activity

1982 ◽  
Vol 28 (2) ◽  
pp. 265-268 ◽  
Author(s):  
J. C. Sirois ◽  
E. A. Peterson
Keyword(s):  
Positive Relationship ◽  
Rhizobium Meliloti ◽  
Nitrogenase Activity ◽  
Screening Method ◽  
Dry Weight ◽  
Rapid Screening ◽  
Experimental Conditions ◽  
Intact Plants ◽  
Medicago Sativa L ◽  
Rapid Screening Method

A method for screening Rhizobium meliloti isolates for their symbiotic nitrogenase activity with alfalfa (Medicago sativa L.) cv. Apollo is described. The nitrogenase activity of each isolate is assessed by measuring the reduction of acetylene (C2H2) to ethylene (C2H4) by 50 intact plants grown in 10 plastic pouches for 2 weeks. The method is rapid, sensitive, reproducible, and accurate enough to differentiate 29 Rhizobium isolates and 5 authentic strains into 13 subsets. Under the experimental conditions used, nodulation occurred within 5 days of inoculation and there was a significant positive relationship between the nitrogenase activity of those isolates which reduced more than 60 nmol C2H2∙plant−1∙h−1 and the dry weight of the shoots of the nodulated plants in 2 weeks of growth.

EFFECTS OF SEED INOCULATION METHODS WITH PEAT-BASED RHIZOBIUM MELILOTI ON ALFALFA

1975 ◽  
Vol 55 (2) ◽  
pp. 555-563 ◽  
Author(s):  
H. T. KUNELIUS ◽  
UMESH C. GUPTA
Keyword(s):  
Soil Ph ◽  
Dry Matter ◽  
Rhizobium Meliloti ◽  
Sandy Loam ◽  
Good Growth ◽  
Seed Treatments ◽  
Fine Sandy Loam ◽  
Seed Inoculation ◽  
Medicago Sativa L ◽  
Uniform Manner

Saranac alfalfa (Medicago sativa L.) was grown on Charlottetown fine sandy loam (CHFSL) and Culloden sandy loam (CSL) in the greenhouse and field. Uninoculated, inoculated with peat-based rhizobia (I), inoculated and molybdenum-treated (IMo), inoculated and lime-coated (ILC), and inoculated, lime-coated and Mo-treated (ILCMo) seeds were included. At soil pH 5.0 and 5.3 in the greenhouse, the dry weights of alfalfa ranged from 214 to 727 mg/plant in the four cuttings from the ILC and ILCMo seed. The dry weights of alfalfa from the I and IMo seed were 1.3 to 99.7% of those from the ILCMo seed. Alfalfa from the ILC and ILCMo seed was well nodulated, whereas I and IMo seed resulted in poor nodulation. The 1973 field experiment showed that ILC and ILCMo seed at soil pH 5.5 and 5.6 resulted in alfalfa dry matter (DM) yields of 4,050 and 4,830 kg/ha which were equal to DM yields from plots with a pH of 6.0 and 6.1 seeded with inoculated seed. In plots with pH 5.5 and 5.6, total DM yields from I and IMo seed were 26.0–49.7% lower than those from ILCMo seed. In 1972, seed treatments on CHFSL at pH 5.6 did not influence the DM yields of alfalfa, whereas on CSL at pH 5.2 the crop failed to establish except from ILC and ILCMo seed and in limed plots at pH 5.9. In the first cutting, high N concentrations of alfalfa tissue coincided with good growth and good nodulation. The Mo concentrations of alfalfa tissue were not influenced in a uniform manner by seed treatments and varied from 0.11 to 0.49 ppm in the first cut tissue.

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.

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.

Influence of nitrogen supply on developmental kinetics of symbiotic and nonsymbiotic alfalfa cv. Algonquin through first flowering

1985 ◽  
Vol 63 (4) ◽  
pp. 841-846 ◽  
Author(s):  
F. D. H. Macdowall
Keyword(s):  
Rhizobium Meliloti ◽  
Reduced Form ◽  
Controlled Environment ◽  
Negative Change ◽  
N Assimilation ◽  
Temporary Water ◽  
Medicago Sativa L ◽  
Optimum Formula ◽  
Kinetics Of ◽  
At Will

Sterile or inoculated (Rhizobium meliloti, 102F70) seedlings of Medicago sativa L. cv. Algonquin were grown for 35 or more days in vermiculite in controlled-environment rooms and supplied with Hoagland's solution modified by differing N content. When growth was supported by optimum [Formula: see text] concentration, a high [Formula: see text] changed to a lower value (negative change) at 27 ± 2 days of age, and when growth was symbiotic, a low initial [Formula: see text] changed to a higher value at the same time. These changes could be induced earlier at will by means of a transient supply of [Formula: see text] or by temporary water deficiency. The negative change occurred later during growth in nutrients containing combined N in a reduced form. Hypothetical roles of N assimilation in some of the kinetic changes were discussed.

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.

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