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.

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.

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.

scholarly journals EFFETS DES SOUCHES DE RHIZOBIUM MELILOTI ET DES COUPES SUCCESSIVES DE LA LUZERNE (MEDICAGO SATIVA) SUR LA FIXATION SYMBIOTIQUE D’AZOTE

1977 ◽  
Vol 57 (2) ◽  
pp. 433-439 ◽  
Author(s):  
L. M. BORDELEAU ◽  
H. ANTOUN ◽  
R. A. LACHANCE
Keyword(s):  
Nitrogen Fixation ◽  
Medicago Sativa ◽  
Statistical Study ◽  
Symbiotic Nitrogen Fixation ◽  
Rhizobium Meliloti ◽  
Dry Weight ◽  
Indirect Measurement ◽  
Controlled Environment ◽  
Symbiotic Efficiency ◽  
Plant Yield

Symbiotic nitrogen fixation with 49 isolates of Rhizobium meliloti was studied under controlled environment with alfalfa cv. Saranac. It was shown that plant yield in dry weight can be used as an indirect measurement of nitrogen fixation, and as a criterion for selecting efficient strains of R. meliloti. Statistical study on yields of three cuttings has established that the second cutting gives the most necessary information to correctly evaluate the symbiotic efficiency of the isolates. Six very efficient strains were selected.

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.

Influence of the earthworm Aporrectodea trapezoides (Lumbricidae) on the colonization of alfalfa (Medicago sativa L.) roots by Rhizobium meliloti L5-30R and the survival of R. meliloti L5-30R in soil

1994 ◽  
Vol 18 (1) ◽  
pp. 63-70 ◽  
Author(s):  
Peter M. Stephens ◽  
Christopher W. Davoren ◽  
Maarten H. Ryder ◽  
Bernard M. Doube
Keyword(s):  
Medicago Sativa ◽  
Rhizobium Meliloti ◽  
Aporrectodea Trapezoides ◽  
Medicago Sativa L

ELISA evaluation of the competitive abilities of two Rhizobium meliloti strains

1984 ◽  
Vol 30 (9) ◽  
pp. 1187-1190 ◽  
Author(s):  
W. A. Rice ◽  
P. E. Olsen ◽  
W. J. Page
Keyword(s):  
Rhizobium Meliloti ◽  
Strain Ratio ◽  
Enzyme Linked Immunosorbent Assay ◽  
Western Canada ◽  
Plant Weight ◽  
Single Strain ◽  
Total Plant ◽  
Medicago Sativa L ◽  
Competitive Abilities ◽  
Inoculum Strain

The double antibody sandwich enzyme-linked immunosorbent assay (DAS-EL1SA) was used to determine the competitive abilities of Rhizobium meliloti strains BALSAC and NRG-185 which are used in commercial alfalfa inoculants for eastern and western Canada, respectively. The ratio of NRG-185:BALSAC in the inoculum applied to aseptically grown alfalfa (Medicago sativa L.) was adjusted to 0:100, 1:99, 50:50, 90:10, 99:1, or 100:0. The ratios between nodules containing only the BALSAC strain and nodules containing only strain NRG-185 were similar to their respective inoculum strain ratios. Nodules containing both strains occurred only with the inoculum strain ratio of 50:50. Total plant weights were highest with the two single strain inocula and were decreased 5–19% with dual strain inoculation. The decrease in total plant weight was significantly correlated with decreases in nodule number and nodule weight. The results suggest that R. meliloti strains BALSAC and NRG-185 have equal competitive abilities, but are somewhat antagonistic, resulting in decreased nodulation and plant growth when both are present in an inoculum.

scholarly journals Direct Diels-Alder reaction of chitin derived 3-acetamido-5-acetylfuran

2022 ◽  
Author(s):  
Rafael Gomes ◽  
Juliana Pereira ◽  
João Ravasco ◽  
João Vale ◽  
Fausto Queda
Keyword(s):  
Alder Reaction ◽  
Diels Alder ◽  
Fine Tuning ◽  
Reduced Form ◽  
Partial Hydrolysis ◽  
Reaction Conditions ◽  
Diels Alder Reaction ◽  
Direct Use ◽  
Kinetics Of ◽  
Hydrolysis Of

The Diels-Alder (DA) reaction of biomass derived furans is an emerging technology for the preparation of new molecular entities and “drop-in” commodity chemicals. In this work we address the challenge of the direct use of electron-poor furanic platforms as dienes through the use of an unexplored chitin derived furan, 3-acetamido-5-acetylfuran (3A5AF). The 3-acetamido group promoted a remarkable increase in the kinetics of the DA allowing for the preparation of 7-oxanorbornenes (7-ONB) at 50 ºC. Partial hydrolysis of the enamide to hemi-acylaminals was possible upon fine tuning of the reaction conditions, disabling retro-DA processes. Finally, DA reaction of the reduced form of 3A5AF allowed quantitative formation of 7-ONB in aqueous condition after 10 minutes. Certanly these are the first steps for expanding the toolbox of chitin derived 3A5AF as diene.

Symbiotic characteristics of Rhizobium meliloti: and appraisal of the systematic treatment of nodulation and nitrogen fixation interactions between hosts and Rhizobia of diverse origins

1966 ◽  
Vol 17 (6) ◽  
pp. 885 ◽  
Author(s):  
J Brockwell ◽  
FW Hely
Keyword(s):  
Nitrogen Fixation ◽  
Host Species ◽  
Rhizobium Meliloti ◽  
Small Degree ◽  
Nodule Formation ◽  
Systematic Treatment ◽  
Diverse Origin ◽  
Medicago Rugosa ◽  
Medicago Sativa L ◽  
Symbiotic Properties

The symbiotic properties of 42 isolates of Rhizobium meliloti collected from widely separated sites in the upper basin of the Darling River were tested in bacteriologically controlled culture with 18 species and varieties of Medicago, three species of Melilotus, and one species of Trigonella. Seven strains of Rh. Meliloti of commercial interest were included in the experiments for comparative purposes. Nodule formation occurred on all plants in 889 out of 974 symbiotic combinations examined. Only Medicago laciniata (L.) Mill, among the hosts and the isolate from M. laciniata among the rhizobia exhibited distinctive nodule formation behaviour. Nitrogen fixation occurred in 637 combinations. On the basis of nitrogen fixation, eight groups of Rh. Meliloti were recognized; there were nine host groups. The groups could be arranged in an interlocking pattern of increasing host and bacterial specificity. These results, which modified to a small degree the bacterial and host groupings previously reported, strongly suggested that the pattern will be widely applicable to Rh. meliloti of diverse origin. In general, the isolates examined were promiscuous and 24 were capable of effective symbioses in association with 10 or more of the hosts. M. laciniata, Trigonella suavissima Lindl., and Medicago rugosa Desr. were the hosts most highly strain-specific in their requirements for nitrogen fixation, and Medicago sativa L. was the most promiscuous. A system for classifying host species into compatibility groups is proposed.

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