Variation in ability of Rhizobium leguminosarum isolates to fix dinitrogen symbiotically in the presence of ammonium nitrate

1983 ◽  
Vol 29 (12) ◽  
pp. 1626-1633 ◽  
Author(s):  
Louise M. Nelson

To assess the variation in symbiotic effectiveness of N2-fixing Rhizobium leguminosarum isolates in the presence of NH4NO3, peas were inoculated with 38 isolates and grown for 4 weeks with weekly additions of 2 mM NH4NO3. Acetylene reduction was inhibited relative to a N-free control in all isolates but the inhibition varied from 60 to 100%. There were also significant differences (p = 0.05) between isolates with varying inhibition of C2H2 reduction in H2 uptake, H2 evolution, and leghemoglobin content. Ten isolates were selected for further study of the importance of NH4NO3 concentration (0, 1,2, and 5 mM) and plant growth stage (3,4, and 5 weeks) to characters associated with N2 fixation and plant growth. Plant age, NH4NO3 treatment, and isolate were all significant sources of variation (p ≤ 0.01) for each character measured but interactions between these factors were also significant. There were significant differences between isolates in the rate of decrease in C2H2 reduction with increasing NH4NO3 concentration (C2H2 reduction responsiveness to NH4NO3) and this responsiveness term was correlated with C2H2 reduction rates at 2 and 5 mM NH4NO3 (p = 0.01). Acetylene reduction rates were correlated with shoot dry weights at 0.1, and 2 mM NH4NO3 (p = 0.001). These results suggest the possibility of enhancing N2 fixation in peas through selection of rhizobia with maximum effectiveness at low levels of combined nitrogen.


1987 ◽  
Vol 65 (12) ◽  
pp. 2542-2548 ◽  
Author(s):  
François-P. Chalifour ◽  
Louise M. Nelson

Combined nitrogen (N) has adverse effects on virtually all stages of the Rhizobium–legume symbiosis. Tolerance to combined N varies among legume hosts and rhizobial isolates, but the contribution of each symbiotic partner is not well established. The effects of combined N were studied in faba bean (Vicia faba L.) and pea (Pisum sativum L.), using the same Rhizobium leguminosarum isolates for both hosts. In one experiment, faba bean and pea were inoculated individually with four rhizobial isolates and grown for 28 days in the continuous presence of 0, 2.5, 5.0, or7.5 mol m−3 NH4NO3. For each isolate, faba bean was consistently more tolerant to combined N than pea as shown by significantly smaller rates of decrease in N2-fixing activity (acetylene reduction) in faba bean than in pea. The results were substantiated by those of a similar experiment in which increasing levels of 15N-labeled [Formula: see text] (5, 10, or 15 mol m−3) were supplied continuously to faba bean and pea inoculated individually with two rhizobial isolates. Comparisons of the different symbioses based on the proportion of total plant N derived from N2 fixation confirmed the conclusions reached using acetylene reduction activities.



1970 ◽  
Vol 17 ◽  
pp. 17-22 ◽  
Author(s):  
Kamal Singh ◽  
A. A. Khan ◽  
Iram Khan ◽  
Rose Rizvi ◽  
M. Saquib

Plant growth, yield, pigment and protein content of cow-pea were increased significantly at lower levels (20 and 40%) of fly ash but reverse was true at higher levels (80 and 100%). Soil amended by 60% fly ash could cause suppression in growth and yield in respect to 40% fly ash treated cow-pea plants but former was found at par with control (fly ash untreated plants). Maximum growth occurred in plants grown in soil amended with 40% fly ash. Nitrogen content of cow-pea was suppressed progressively in increasing levels of fly ash. Moreover,  Rhizobium leguminosarum  influenced the growth and yield positively but Meloidogyne javanica caused opposite effects particularly at 20 and 40% fly ash levels. The positive effects of R. leguminosarum were marked by M. javanica at initial levels. However, at 80 and 100% fly ash levels, the positive and negative effects of R. leguminosarum and/or M. javanica did not appear as insignificant difference persist among such treatments.Key words:  Meloidogyne javanica; Rhizobium leguminosarum; Fly ash; Growth; YieldDOI: 10.3126/eco.v17i0.4098Ecoprint An International Journal of Ecology Vol. 17, 2010 Page: 17-22 Uploaded date: 28 December, 2010  



1988 ◽  
Vol 80 (4) ◽  
pp. 586-591 ◽  
Author(s):  
W. B. Hallmark ◽  
C. J. DeMooy ◽  
H. F. Mooris ◽  
John Pesek ◽  
K. P. Shao ◽  
...  


Crop Science ◽  
1989 ◽  
Vol 29 (6) ◽  
pp. 1412-1416 ◽  
Author(s):  
L. R. Goulart ◽  
H. W. Ohm ◽  
J. E. Foster


2005 ◽  
Vol 54 (2) ◽  
pp. 142-147 ◽  
Author(s):  
Fauzia Y. Hafeez ◽  
Farrukh I. Naeem ◽  
Rehan Naeem ◽  
Arsalan H. Zaidi ◽  
Kausar A. Malik


2015 ◽  
Vol 33 (3) ◽  
pp. 509-519 ◽  
Author(s):  
C. A. DAMALAS ◽  
T. K. GITSOPOULOS ◽  
S.D. KOUTROUBAS ◽  
I. GEORGOULAS

ABSTRACTPanicoid grasses are major weeds of maize and sugarcane as well as of several other important grains, including sorghum, pearl millet, and foxtail millet. Pot trials were conducted to study the activity and potential interactions of topramezone in mixture with recommended rates of rimsulfuron or nicosulfuron on three annual panicoid grasses (i.e. Echinochloa oryzoides,E.phyllopogon, and Panicum miliaceum). Target weeds were treated at the four- to five-leaf growth stage. On the basis of fresh weight reduction, topramezone alone provided 78% control of E.oryzoides, 68% control of E.phyllopogon, and 99% control of P.miliaceum. Topramezone plus rimsulfuron or nicosulfuron provided decreased control of both Echinochloa spp. compared with topramezone alone. The decreased control of E.oryzoidesand E.phyllopogon was more pronounced with rimsulfuron as a companion herbicide in the mixtures. Slightly decreased control of P.milaceum was observed with topramezone plus rimsulfuron compared with topramezone alone, but this was not the case for topramezone plus nicosulfuron. Increased topramezone rates mixed with rimsulfuron or nicosulfuron did not improve control of E.oryzoides and E.phyllopogon compared with the lowest topramezone rate. Also, increased topramezone rates mixed with rimsulfuron or nicosulfuron showed decreased control of both Echinochloa spp. when compared with either rimsulfuron or nicosulfuron alone, suggesting a two-way interaction between topramezone and the ALS-inhibiting herbicides. The above-mentioned interaction was not observed in P.miliaceum, probably related with species sensitivity to the herbicides tested. Newly introduced or naturalized panicoid grasses in maize fields may complicate selection of companion herbicides and rates for effective weed control.



2013 ◽  
Vol 85 (2) ◽  
pp. 813-822 ◽  
Author(s):  
LEONARDO B. DE CARVALHO ◽  
PEDRO L.C.A. ALVES ◽  
STEPHEN O. DUKE

Weed management systems in almost all Brazilian coffee plantations allow herbicide spray to drift on crop plants. In order to evaluate if there is any effect of the most commonly used herbicide in coffee production, glyphosate, on coffee plants, a range of glyphosate doses were applied directly on coffee plants at two distinct plant growth stages. Although growth of both young and old plants was reduced at higher glyphosate doses, low doses caused no effects on growth characteristics of young plants and stimulated growth of older plants. Therefore, hormesis with glyphosate is dependent on coffee plant growth stage at the time of herbicide application.



1998 ◽  
Vol 17 (5) ◽  
pp. 272-277 ◽  
Author(s):  
D J Morré

A number of solvents including ethyl, amyl, butyl, octyl and benzyl alcohols, ethylene glycol, ethyl acetate, acetone, diethyl ether, propylene oxide, r-dioxane, benzene, xylene, chloroform and carbon tetrachloride stimulate the growth of plants or plant parts at low concentrations and inhibit at high concentrations. These same solvents, at low dilutions, stimulate the activity of a growth-related protein disulfide-thiol interchange protein (TIP) with NADH: protein disulfide reductase (NADH oxidase) (NOX) activity with plasma membrane vesicles isolated from elongating regions cut from dark grown seedlings of soybeans. Based on these and other findings, we suggest the TIP/NOX protein to be the molecular target of the biological effects of low levels of exposure (hormesis) involved in the stimulation of plant growth.



2015 ◽  
Vol 33 (3) ◽  
pp. 521-534 ◽  
Author(s):  
G. B. P BRAZ ◽  
R. S OLIVEIRA JR ◽  
J. CONSTANTIN ◽  
H. K. TAKANO ◽  
C. A. CHASE ◽  
...  

ABSTRACT The increase in the area planted with Crotalaria spectabilishas occurred by several factors, highlighting the potential to reduce the nematodes, nitrogen fixation and the high production of biomass. By becoming a species sown as a crop, it is necessary to control the weeds that coexist with showy crotalaria. This change in the use of this crop creates the possibility of this specie becoming a weed. The aim of this study was to assess the potential use of herbicides applied in preemergence and postemergence of C.spectabilisfor different purposes (control of volunteer and selectivity plants). Three experiments were installed in a greenhouse (two with herbicides applied in preemergence - in soils with distinct textural categories; and one experiment with herbicides applied in postemergence). The results of the experiments with herbicides applied in preemergence showed that: amicarbazone, atrazine, diuron, metribuzin, prometryn, fomesafen and sulfentrazone showed effectiveness for control of C.spectabilis in clayey soil. Besides these, flumioxazin and isoxaflutole also showed potential to be used in the control of showy crotalaria in soils with loam texture. In relation to the postemergence herbicides, atrazine, diuron, prometryn, flumioxazin, fomesafen, lactofen, saflufenacil, amonio-glufosinate and glyphosate can be used aiming the chemical control of C.spectabilis. Herbicides chlorimuron-ethyl, diclosulan, imazethapyr, pyrithiobac-sodium, trifloxysulfuron-sodium, clomazone, pendimethalin, S-metolachlor and trifluralin applied in preemergence, and imazethapyr, pyrithiobac-sodium, flumiclorac, bentazon and clethodim applied in postemergence caused low levels of injury to C.spectabilis plants, making necessary the development of new searches to ensure the selectivity of these products.



1994 ◽  
Vol 72 (7) ◽  
pp. 940-945 ◽  
Author(s):  
R. Lennihan ◽  
D. M. Chapin ◽  
L. G. Dickson

Nostoc commune, a colonial cyanobacterium, has been suggested as an important contributor of nitrogen to terrestrial ecosystems in the Canadian High Arctic, yet little is known about the ecophysiology of this organism in arctic environments. This study focused on the physiological performance of macroscopic colonies of N. commune found on Devon Island, N.W.T. The objectives were to examine the influence of temperature, colony morphology, and seasonal phenology on nitrogen fixation rates and the effects of light and temperature on photosynthesis. Maximum rates of acetylene reduction in N. commune (2119 nmol C2H4∙g−1∙h−1) were higher than those previously recorded for arctic N. commune but lower than values reported for temperate poulations. Depending on the time of the growing season, the temperature optimum for acetylene reduction varied from 15 °C to greater than 20 °C. Photosynthetic temperature optima did not occur below 20–25 °C (the highest temperatures measured). Light saturation of photosynthesis was reached at low levels of irradiance (100–150 μmol∙m−2∙s−1 PPFD). Acetylene reduction rates varied strongly with colony morphology. Thin, fragile, flattened colonies had higher rates than thicker, more resilient, flattened colonies or spherical colonies. Cold post-thaw temperatures appeared to delay the recovery of maximum nitrogen fixation rates for 2–3 weeks following the onset of the growing season. Compared with two other species of cyanobacteria present on Truelove Lowland (Gloeocapsa alpina and Gleotrichia sp.), N. commune had higher rates of nitrogen fixation. Key words: Nostoc commune, cyanobacteria, High Arctic, nitrogen fixation, photosynthesis.



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