Water potentials of seeds of Bromus inermis and Medicago sativa imbibed on media of various osmotic potentials

1976 ◽  
Vol 54 (17) ◽  
pp. 1997-1999 ◽  
Author(s):  
W. T. McDonough
Keyword(s):  
Polyethylene Glycol ◽  
Medicago Sativa ◽  
Bromus Inermis ◽  
Smooth Brome ◽  
Thermocouple Psychrometer ◽  
Water Potentials ◽  
The Media ◽  
Medicago Sativa L ◽  
Brome Grass ◽  
Osmotic Potentials

Seeds of smooth brome grass (Bromus inermis Leyss.) and alfalfa (Medicago sativa L. cultivar Ladak) were allowed to imbibe in water or solutions of polyethylene glycol (Carbowax 1540), mannitol, or sodium chloride. Seed water potentials were determined over a 72-h period after transfer of seeds to thermocouple psychrometer chambers. Seed water potentials were lower than osmotic potentials of the media, but these two potentials were not clearly related to each other. Possible reasons for the lack of gradation in response are discussed.

NITROGENASE ACTIVITY OF ALFALFA GROWN ALONE AND IN MIXTURE WITH GRASS UNDER GREENHOUSE CONDITIONS

1985 ◽  
Vol 65 (3) ◽  
pp. 787-791
Author(s):  
H. A. BURITY ◽  
B. E. COULMAN ◽  
M. A. FARIS
Keyword(s):  
Medicago Sativa ◽  
Nitrogenase Activity ◽  
Dactylis Glomerata ◽  
Phleum Pratense ◽  
Bromus Inermis ◽  
Smooth Bromegrass ◽  
Medicago Sativa L ◽  
Dactylis Glomerata L ◽  
Phleum Pratense L ◽  
Nodule Tissue

A greenhouse experiment has shown that total nitrogenase activity of alfalfa (Medicago sativa L.) is not significantly affected when grown in association with timothy (Phleum pratense L.), smooth bromegrass (Bromus inermis Leyss) or orchardgrass (Dactylis glomerata L.) except after initial harvest when decreased alfalfa activity was associated with smooth bromegrass or orchardgrass. It was concluded that mixed cultures of alfalfa with timothy, smooth bromegrass or orchardgrass have no effect on alfalfa N2 fixation. The results also suggest the occurrence of N transference from alfalfa to associated grasses. It is speculated that this transfer is not primarily due to the death of roots and nodule tissue (after harvest), but involves some degree of N excretion during the period before initial harvest.Key words: Alfalfa-grass mixtures, N2-fixation, nodule activity, N-transference

Corrigenda - Measurement of the total water potential of aqueous solutions of polyethylene glycol - A comparison between osmometer, thermocouple psychrometer and equilibrated soil cores

Soil Research ◽  
1993 ◽  
Vol 31 (1) ◽  
pp. 1
Author(s):  
IM Wood ◽  
IK Dart ◽  
HB So
Keyword(s):  
Polyethylene Glycol ◽  
Water Potential ◽  
Close Correlation ◽  
Ease Of Use ◽  
Effect Of Temperature ◽  
Soil Cores ◽  
Total Water ◽  
Matric Potential ◽  
Thermocouple Psychrometer ◽  
Water Potentials

This study examined two polyethylene glycol (PEG) polymers (PEG 6000 and PEG 10000) and compared measurements of water potential obtained with a thermocouple osmometer and thermocouple psychrometers at three temperatures (15, 25 and 35�C) and five osmdalities (50, 100, 200, 300 and 400 g/1000 g water). These were then compared with estimates of matric potential of three soils brought to equilibrium with PEG solutions of the same osmolalities. At the same osmolality and temperature the two PEG polymers gave essentially the same water potential. There was a significant effect of temperature on water potential which corresponded closely with changes in specific gravity of the PEG solution. There was a close correlation between the measurements of water potential of the PEG solutions obtained with the osmometer and the psychrometers (R = 0.99). However, the psychrometer gave increasingly lower values than the osmometer as water potential decreased. The differences in the measurements between the two methods are thought to be the result of design and calibration differences. The ease of use of the osmometer is such that it is recommended for routine use. The water potentials of the soil cores brought to equilibrium with the PEG 10 000 solution were linearly related to the water potentials of the PEG solutions estimated from both the osmometer and psychrometers (R2 = 0.84). However, there were clear deviations from a 1:l relationship. It was concluded that the results from the soil cores could not be used to determine which of the two instruments gave the more accurate measurement of water potential of PEG solutions.

PASTURE PRODUCTIVITY OF TWO GRASS–ALFALFA MIXTURES IN NORTHEASTERN SASKATCHEWAN

1965 ◽  
Vol 45 (2) ◽  
pp. 162-168 ◽  
Author(s):  
D. A. Cooke ◽  
S. E. Beacom ◽  
W. K. Dawley
Keyword(s):  
Medicago Sativa ◽  
Dry Matter ◽  
Bromus Inermis ◽  
Beef Production ◽  
Rotational Grazing ◽  
Standard Mixture ◽  
Intermediate Wheatgrass ◽  
Medicago Sativa L ◽  
Annual Application ◽  
Average Yearly Increase

Two grass–alfalfa mixtures were compared for seven consecutive years when continuously and when rotationally grazed by yearling Hereford steers. The productivity of rotationally grazed pastures as affected by annual application of fertilizers was also determined. Intermediate wheatgrass (Agropyron intermedium L.) and alfalfa (Medicago sativa L.) compared favorably with the standard mixture of bromegrass (Bromus inermis L.) and alfalfa for pasture purposes. Production of dry matter ranged from approximately 2.5 to 0.5 tons per acre in the first and seventh year respectively. Precipitation in these two years was 20.7 and 7.7 in. respectively. Rotational grazing did not increase beef production. Fertilization of bromegrass–alfalfa with 20 lb of N per acre and with 20 lb of N + 40 lb of P2O5 per acre resulted in average yearly increase of 18 and 32 lb of beef per acre respectively. Fertilization of intermediate wheatgrass– alfalfa resulted in comparable increase of 1 and 26 lb of beef per acre respectively.

POLISH RAPESEED AS A COMPANION CROP FOR ESTABLISHING FORAGES IN NORTHEASTERN SASKATCHEWAN

1984 ◽  
Vol 64 (3) ◽  
pp. 677-682 ◽  
Author(s):  
J. WADDINGTON ◽  
S. BITTMAN
Keyword(s):  
Medicago Sativa ◽  
Brassica Campestris ◽  
Growth Suppression ◽  
Bromus Inermis ◽  
Seeding Date ◽  
Forage Species ◽  
Medicago Sativa L ◽  
Companion Crop

Forages were seeded with and without a Polish rapeseed (Brassica campestris L.) companion crop at two dates in each of 3 yr. In each test, forage seedlings grew much better where seeded alone; growth under the companion crop varied from poor to fairly good, depending on the year and the forage species. Russian wild ryegrass (Elymus junceus Fisch.) established poorly under rapeseed. Bromegrass (Bromus inermis Leyss.) establishment was satisfactory in all tests, although production in the year following was usually much less than where it was seeded alone. Alfalfa (Medicago sativa L.) and sainfoin (Onobrychis viciaefolia Scop.) establishment was poor to fair under rapeseed. A mid-May seeding date with the companion crop resulted in better forage growth by fall than a later seeding date. A feature of all tests was the severe infestation of volunteer rapeseed the year following seeding in all forages except bromegrass. Because of growth suppression during the establishment year, and difficulties with volunteer rapeseed in legumes in the year following establishment, it is suggested that Polish rapeseed is not a good companion crop when establishing legumes and Russian wild ryegrass.Key words: Bromegrass, alfalfa, Russian wild ryegrass, sainfoin, rapeseed, companion crops, forage establishment

Performance of alfalfa strains grown in mixture with smooth bromegrass as affected by management

1991 ◽  
Vol 71 (4) ◽  
pp. 1029-1037 ◽  
Author(s):  
S. Bittman ◽  
J. Waddington ◽  
D. H. McCartney
Keyword(s):  
Binary Mixture ◽  
Medicago Sativa ◽  
Total Yield ◽  
Bromus Inermis ◽  
Smooth Bromegrass ◽  
P Fertilizer ◽  
Medicago Sativa L ◽  
Long Term Performance ◽  
Term Performance

This study was conducted to evaluate the yield and persistence of seven contrasting alfalfa (Medicago sativa L. sensu lato) strains growing in binary mixture with smooth bromegrass (Bromus inermis Leyss.) under different fertilizer and cutting managements. The alfalfa strains were seeded in mixtures with smooth bromegrass in 1980 in northeast Saskatchewan and harvested each year, 1982 through 1987. Two fertilizer treatments (0 and 18 kg ha−1 P) and two cutting managements (2 and 3-4 cuts) were imposed annually. The application of P fertilizer increased the total yield (6-yr average) from 1.47 t ha−1 in control plots to 2.52 t ha−1 in the fertilized plots. Frequent cutting reduced average total yield from 2.59 t ha−1 (2-cut system) to 1.4 t ha−1. Fertility and cutting management did not affect the proportion of alfalfa or weeds in the harvested herbage. The alfalfa strain significantly affected total yield and the proportion of alfalfa and weeds throughout the years of this study. The strain ScMf3713, a M. sativa subsp. falcata (L.) Arcang. type, outyielded all entries during the last 3 yr of this study. The study suggests that alfalfa strains of the falcata subspecies germplasm showed superior long-term performance when the alfalfa was grown in a binary mixture with bromegrass. Key words: Medicago sativa L., falcata, Bromus inermis Leyss., phosphorus, simulated grazing

Measurement of the total water potential of aqueous solutions of polyethylene glycol - A comparison between osmometer, thermocouple psychrometer and equilibrated soil cores

Soil Research ◽  
1993 ◽  
Vol 31 (1) ◽  
pp. 1 ◽  
Author(s):  
IM Wood ◽  
IK Dart ◽  
HB So
Keyword(s):  
Polyethylene Glycol ◽  
Water Potential ◽  
Close Correlation ◽  
Ease Of Use ◽  
Effect Of Temperature ◽  
Soil Cores ◽  
Total Water ◽  
Matric Potential ◽  
Thermocouple Psychrometer ◽  
Water Potentials

This study examined two polyethylene glycol (PEG) polymers (PEG 6000 and PEG 10000) and compared measurements of water potential obtained with a thermocouple osmometer and thermocouple psychrometers at three temperatures (15, 25 and 35�C) and five osmdalities (50, 100, 200, 300 and 400 g/1000 g water). These were then compared with estimates of matric potential of three soils brought to equilibrium with PEG solutions of the same osmolalities. At the same osmolality and temperature the two PEG polymers gave essentially the same water potential. There was a significant effect of temperature on water potential which corresponded closely with changes in specific gravity of the PEG solution. There was a close correlation between the measurements of water potential of the PEG solutions obtained with the osmometer and the psychrometers (R = 0.99). However, the psychrometer gave increasingly lower values than the osmometer as water potential decreased. The differences in the measurements between the two methods are thought to be the result of design and calibration differences. The ease of use of the osmometer is such that it is recommended for routine use. The water potentials of the soil cores brought to equilibrium with the PEG 10 000 solution were linearly related to the water potentials of the PEG solutions estimated from both the osmometer and psychrometers (R2 = 0.84). However, there were clear deviations from a 1:l relationship. It was concluded that the results from the soil cores could not be used to determine which of the two instruments gave the more accurate measurement of water potential of PEG solutions.

EFFECTS OF INITIAL HARVEST DATE ON PRODUCTIVITY AND PERSISTENCE OF ALFALFA AND BROMEGRASS

1972 ◽  
Vol 52 (5) ◽  
pp. 801-804 ◽  
Author(s):  
J. D. McELGUNN ◽  
D. H. HEINRICHS ◽  
R. ASHFORD
Keyword(s):  
Nitrogen Fixation ◽  
Medicago Sativa ◽  
Taraxacum Officinale ◽  
Bromus Inermis ◽  
Harvest Date ◽  
Mixed Stands ◽  
Medicago Sativa L ◽  
Made In

Alfalfa (Medicago sativa L.), bromegrass (Bromus inermis Leyss.), and a mixture of the two were grown on irrigated land and subjected to six defoliation schedules in which the initial cutting date varied in time. Delaying the initial defoliation until mid-June resulted in greatest seasonal yield even though the last cutting in this schedule was made in the 1st week of September, usually considered somewhat late for cutting in Saskatchewan. Nitrogen at the rate of 112 kg/ha doubled the yield of bromegrass but did not increase the yield of the alfalfa–bromegrass mixture, indicating that nitrogen fixation was adequate for the crop. Alfalfa and the alfalfa–bromegrass mixtures yielded about 50% more forage than the N-fertilized bromegrass and three times as much as unfertilized bromegrass. At the end of the experiment, dandelions (Taraxacum officinale Weber) had invaded pure stands of alfalfa but not mixed stands of alfalfa and bromegrass.

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