摘要:

not available

ISSN:1923-4287    

DOI:10.1139/cjr47c-017

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

Effects of steam sterilization and recontamination with original soil, on certain physical, chemical, and biological properties of four Alberta soils were investigated. The soils were Edmonton black loam, Vegreville black fine sandy loam, Gros Ventre brown loam, and Fallis gray silt loam. Certain physical properties were affected by steam sterilization as follows: (1) capillary rise of moisture was greatly retarded in all four soils following sterilization; (2) the percentages of the different separates as determined by ordinary mechanical analysis were not changed significantly by sterilization; (3) water-holding capacity and moisture content at the 'sticky point' were slightly reduced, and, in three of the soils, shrinkage was slightly increased by sterilization, but these effects were of uncertain significance; (4) the pH values of these soils were not changed appreciably by sterilization. The following chemical changes were produced by steam sterilization: (1) water-soluble phosphate was generally greatly increased and water soluble sulphate somewhat increased by sterilization. Easily soluble phosphorus (soluble at pH 3) was increased by about one-third in the two black soils rich in organic matter, but not in the other soils; (2) ammonia accumulated rapidly in the sterilized recontaminated black and brown soils for four to six weeks, and then returned to normal in 8 to 12 weeks. Ammonia accumulated less rapidly and to a smaller degree in the gray soil; (3) nitrification was suppressed for about 6 to 10 weeks in the sterilized recontaminated soils, but was later more active in these soils than in the unsterilized (especially in the black soils rich in organic matter).

ISSN:1923-4287    

DOI:10.1139/cjr47c-018

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

A distinction is drawn between the virgin fescue prairie described as theFestuca scabrellaassociation, and the fescue grassland produced by mowing for hay or by grazing. The virgin or climax association, dominated byFestuca scabrella, is characterized by some 150 species of higher plants. Various of the associated species, notably a few of the grasses, increase greatly in frequency and coverage when the prairie is used as hay meadow or as pasture, while the fescue shows a corresponding decline. Where grazing has been heavy the fescue has virtually disappeared. The fescue association is considered in relation toStipa, poplar, and other contiguous plant communities. The name 'submontane' for the fescue prairie of Alberta and Saskatchewan is inappropriate. The fescue association is believed to have been associated with the formation of the black soils of Alberta, including the soils of those black and gray-black zones occupied in recent times by wooded vegetation. The bulk of the organic matter in the black soils has apparently derived from a single species of grass, viz.Festuca scabrella. An understanding of climax communities and successional relationships is basic to a proper classification of range land for lease purposes, and to sound long-term administrative policy for this land.

ISSN:1923-4287    

DOI:10.1139/cjr47c-019

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

Soil bacteria that hydrolyze starch were isolated by means of an elective culture medium with this polysaccharide as the sole source of carbon; their ability to decompose cellulose was then tested. Thirteen strains of cellulose decomposing bacteria were thus isolated from several Quebec soils. The bacteria have been assigned to three recognized genera under eight new specific names. Their elevation to species rank is based on differentiations comparable to those used in Bergey's Manual. The following new species have been proposed:Vibrio perimastix,Vibrio hyperion,Bacterium infirme,Bacillus vagans,Bacillus Kellermani,Bacillus soli,Bacillus torquens, andBacillus effluens.

ISSN:1923-4287    

DOI:10.1139/cjr47c-020

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

An indicator agar that reveals the approximate concentration of ascorbic acid in potato tuber tissue by direct contact is prepared by heating together 2 gm. agar, 75 ml. water, 10 ml. of a 10% solution of potassium iodide, and 5 ml. of a 1% solution of soluble starch. After cooling to 60 °C., 5 ml. of glacial acetic acid and 5 ml. of an 0.02 Nsolution of potassium iodate are added and the mix is immediately poured into Petri dishes. When uniform filter paper discs saturated with standard ascorbic acid solutions or uniform tuber tissue discs are placed upon the agar surface, after 24 hr. at 5 °C., the size of the area decolorized is directly related to the concentration of ascorbic acid in the solutions and tissue discs. Tissue discs from tubers affected with mosaic and leaf roll decolorize a greater area than discs from normal tubers from the same variety, and the decolorization is independent of tuber size. The diagnostic accuracy of the method is further strengthened by the tendency of virus infected tissue to remain white and healthy tissue to become blue-black.

ISSN:1923-4287    

DOI:10.1139/cjr47c-021

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

The metabolism of an impure culture of an aerobic cellulose decomposing bacterium,Vibrio perimastix, was studied. The products of cellulose decomposition included carbon dioxide, a pigment resembling riboflavin, a bacterial polysaccharide, and traces of acid. Carbon dioxide was found to be essential for the decomposition of cellulose and could not be replaced by calcium carbonate. Increasing the carbon dioxide content of the air above 1.2% retarded growth on a glucose medium.Respiration studies were carried out using cellulose, glucose, and cellobiose as substrates, and the possible role of the latter two as intermediates in cellulose decomposition was investigated. Glucose was produced from cellulose when toluene was added to cultures during active decomposition; evidence is presented that a dialyzable factor produced by the bacteria is essential for glucose formation. Phosphorylation inhibitors prevented growth of the bacteria on cellulose, glucose, and cellobiose, inhibited respiration of active cellulose cultures, and retarded the production of glucose by toluene-treated cultures. Cellulose treated with alkali to increase the proportion of amorphous to crystalline cellulose was more rapidly decomposed than untreated cellulose.

ISSN:1923-4287    

DOI:10.1139/cjr47c-022

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

In the late summer of 1942, aSeptoriasp. with spores longer than those ofSeptoria nodorumBerk., and conforming rather closely to those ofS.AvenaeFrank, was found commonly in the Prairie Provinces of Canada on leaves of wheat and, in one instance, on leaves of barley. It was found again on wheat and more rarely on barley in both Eastern and Western Canada each year from 1943 to 1946. Occasionally, perithecia, attributable to the genusLeptosphaeria, were found on leaves that previously had borne numerous pycnidia of this organism. That the perithecia represented the perfect stage of thisSeptoriasp. was shown by the development of similar perithecia in many cultures established from pycnidiospores, and by the formation of pycnidia in certain cultures grown from ascospores of perithecia collected on wheat. The perithecia, asci, and ascospores conform closely though not identically with the description ofLeptosphaeria avenariaWeber.The organism under discussion differs fromS.nodorumnot only in the size of its pycnidiospores but also in its inability to cause glume blotch, its longer incubation period, and lack of ability to attack the seedlings of certain wheat varieties susceptible toS.nodorum. It differs fromS.Avenaein symptoms, host range, length of incubation period, and cultural characteristics. It differs from both these species by a lower parasitic vigour and a marked tendency to develop on fading leaves and sheaths. Owing to its morphological similarity toL.avenariait is here described as aforma specialisof that species.

ISSN:1923-4287    

DOI:10.1139/cjr47c-023

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

not available

ISSN:1923-4287    

DOI:10.1139/cjr47c-024

出版商:NRC Research Press    

年代:1947

数据来源: NRC