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

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

1981 ◽  
Vol 27 (1) ◽  
pp. 52-56 ◽  
Author(s):  
L. V. Wood ◽  
R. V. Klucas ◽  
R. C. Shearman

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.


1983 ◽  
Vol 61 (9) ◽  
pp. 2405-2409 ◽  
Author(s):  
F. D. H. Macdowall

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.


HortScience ◽  
2005 ◽  
Vol 40 (4) ◽  
pp. 1061A-1061
Author(s):  
Laura M. R. Rinaldi ◽  
Maria C. Margheri ◽  
Alba Ena

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.


2012 ◽  
Vol 46 (2) ◽  
pp. 528-535 ◽  
Author(s):  
Alena (Lihua) Jin ◽  
Jocelyn A. Ozga ◽  
Daise Lopes-Lutz ◽  
Andreas Schieber ◽  
Dennis M. Reinecke

1981 ◽  
Vol 27 (8) ◽  
pp. 815-823 ◽  
Author(s):  
John D. Tjepkema ◽  
William Ormerod ◽  
John G. Torrey

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.


2001 ◽  
Vol 47 (12) ◽  
pp. 1068-1074 ◽  
Author(s):  
Chantal J Beauchamp ◽  
Joseph W Kloepper ◽  
Joseph J Shaw ◽  
François-P. Chalifour

There is a lack of knowledge concerning the effect of nitrate–nitrogen (NO3––N) at levels known to inhibit nodule formation and functioning on root colonization of dinitrogen-fixing legumes. Firstly, this study investigated potential differences between Rhizobium leguminosarum bv. viciae 175F9 and its bioluminescent-labeled strain 175F9.lux on root colonization of faba bean (Vicia faba L.) and pea (Pisum sativum L.). These two strains similarly colonized the roots of both hosts. Secondly, this study evaluated the effects of 0 and 10 mol·m–3 NO3––N on root colonization of faba bean and pea by strain 175F9.lux, over time. Averaged over both hosts and harvest dates, the presence of NO3––N increased the rhizobial population and the root length colonized. In addition, our results showed that bioluminescence activity increased from 7 to 14 days after sowing and was not correlated to rhizobial population. Finally, to demonstrate that an increase in bioluminescence activity was not an indirect effect of nitrate on R. leguminosarum bv. viciae 175F9.lux, this study investigated the effects of increasing carbon (mannitol) and nitrogen (NO3––N) concentrations on the rhizobial population and bioluminescence activity. The carbon source was more important than the nitrogen source to increase the rhizobial population and bioluminescence activity, which increased with increasing mannitol concentration, but not with increasing nitrate concentration. Results from this study demonstrated that NO3––N increased rhizobial population, especially for faba bean, and the length of root colonized.Key words: nitrate, nitrogen, rhizosphere, rhizobacteria, luminescence


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