摘要:

Radioactive phosphorus (P32) was made available to individual germinating seeds and seedlings ofTriticum vulgare,T.durum,T.monococcum, andHordeum distichon. Each treated plant was provided with either 0.18 or 0.018 micro-curies of P32. Both concentrations were effective in causing chromosome breakage and rearrangements. Many aberrant chromosome configurations occurred in microsporocytes of treated tetraploid and hexaploid plants. Only one chromosome aberration was found inT.monococcumand none in barley. Structural changes occurred also in chromosomes of vulgare wheat grown in soil to which fertilizer containing P32was added. It is possible that the effectiveness of small amounts of P32in inducing mutations is increased by its inclusion in chromosome molecules. Emitted beta particles would then be shot off very close to the sensitive target. Further, the recoiling atomic nucleus is almost certain to have enough energy to break any chemical bond. In any case since there is a change in atomic number (from 15 to 16) and in valence (P valence 5, S valence 2), molecular bonds must be released in the process.

ISSN:1923-4287    

DOI:10.1139/cjr48c-011

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

The general similarity in root weight between the populations from reciprocal crosses of tetraploids, the differences between unrelated families, and the divergence between the progeny of large-rooted and small-rooted parents together indicate the operation of genetic factors in root development. Number, size, and shape of leaves likewise appear to be strongly influenced by heredity. As a rule, vigorous rosettes, large roots, and a sparsity or absence of first-year flowering are associated, but diverse assortments of these characteristics occur in some families. Since sparse flowering favors root enlargement, the later blooming and less floriferous tetraploids have an advantage over diploids in that respect. On the whole, random tetraploids possess wider but markedly fewer leaves, slightly smaller leaf area, bloom later and much more sparsely during the first year, and produce larger and more robust roots than diploids.

ISSN:1923-4287    

DOI:10.1139/cjr48c-012

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

In connection with a general taxonomic study of the resupinate Thelephoraceae of Canada, a number of forms have been encountered that appear to be undescribed. In this contribution nine such forms falling in the genusPeniophoraare described and illustrated as probable new species.

ISSN:1923-4287    

DOI:10.1139/cjr48c-013

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

A strain ofUromyces Polygoni(Pers.) Fuckel collected onPolygonum aviculareL. at Winnipeg was found to be homothallic. Attempts to infectP.erectumL. andP.neglectumBesser with sporidia, aeciospores, and urediospores of this rust were unsuccessful. Of the sporidial infections onP.aviculare, whether originating from a single sporidium or from two or more sporidia, most produced aecia only, but some produced uredia only, and a few produced aecia and uredia in association. Pycnia were not visible in any of the sporidial infections when examined with a hand lens but, in microtome sections cut from infections that had developed aecia, a few pycnia containing pycniospores were observed. No flexuous hyphae and periphyses were seen in these pycnia.

ISSN:1923-4287    

DOI:10.1139/cjr48c-014

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

In the following pages nine species ofCorticium, found in Ontario and presumed to be new to science, are described and illustrated. These were encountered in connection with a general taxonomic study of resupinate Thelephoraceae. In addition, a redescription and discussion of a species recently published from Europe, also found to be common in Ontario, is included.

ISSN:1923-4287    

DOI:10.1139/cjr48c-015

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

A description is given of fasciation in a sweet pea plant, from which a strain ofAgrobacterium tumefaciens(Smith and Townsend) Conn was isolated. Germinated and nongerminated sweet pea seed inoculated with the organism were grown in agar, sand, and soil. Fasciation, dwarfing, swollen roots and stems as well as yellowed and crinkled leaves were produced in most of the plants grown in agar and sand. Fewer plants grown in soil were affected. Microscopical examinations revealed organisms in fasciated areas, roots, and stems. The organisms were recovered in each case by plating with Congo red agar.Fasciation was not produced in garden pea plants although some plants were dwarfed. Typical galls were not produced on stems of sweet and garden pea plants by needle inoculations. A description of the organism is given and certain features of its action on sweet pea plants are discussed.

ISSN:1923-4287    

DOI:10.1139/cjr48c-016

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

A synthetic medium inducing high streptomycin production was evolved by studying growth factor and nitrogen requirements of the moldStreptomyces griseus. It was concluded that mycelium growth and streptomycin production do not necessarily parallel each other. Histidine appeared to affect both streptomycin and mycelium formation and was essential in any amino acid combination to induce either a high mycelium or streptomycin yield. Valine was shown to stimulate streptomycin synthesis and aspartic or glutamic promoted only mycelium production. Experiments were done to show which metabolic changes in the medium could be associated with growth and which with the antibiotic production.The effect on the mold of high concentration of sodium chloride was investigated. It was found that by reducing the amount of salt in the nutrient media, the greater part of the streptomycin could be recovered from the mycelium instead of the medium. It appears that the antibiotic is a product of intracellular synthesis, since ions of the lyotropic series affecting the permeability of the cellular membrane affect the distribution of the antibiotic between medium and mycelium.

ISSN:1923-4287    

DOI:10.1139/cjr48c-017

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

A study was made of the growth of rhizobia outside the host plant in three high humus mixtures and a mineral soil. Rhizobia grew better in pure cultures than in an unsterile base. Incubation in Erlenmeyer flasks gave, as a rule, higher counts than in paper cartons. Addition of a mixture of sucrose, calcium carbonate, sodium chloride, dipotassium phosphate, and magnesium sulphate led to increased numbers of rhizobia in pure culture in all bases used, and produced increased numbers in the unsterilized mineral soil also. Addition of this mixture to the unsterile high humus bases increased the total numbers of bacteria, but not the number of rhizobia. When the bases were sterilized, the highest counts of rhizobia were obtained in the high humus bases. When sterilization was not carried out, the greatest numbers of rhizobia occurred in the mineral soil. In tightly stoppered flasks that did not permit aeration, the rhizobia appeared to die out completely when stored for more than a few days, whereas in loosely stoppered flasks the counts remained at a high level until the base became desiccated.

ISSN:1923-4287    

DOI:10.1139/cjr48c-018

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

By the staining of soil with the fluorescent dye acridinorange and examination of the stained soil under the fluorescence microscope, it is possible to observe directly the living bacteria of soil in their autochthonic condition. All humus substances are stained red in color. The bacteria, living on the humus particles, are of green fluorescence and give an excellent contrast against the red background. The bacteria are vitally stained and can be used for culture experiments. Using this method in some soil tests the autochthonic bacteria of soil have been investigated qualitatively and quantitatively.

ISSN:1923-4287    

DOI:10.1139/cjr48c-019

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

The ease with which lettuce seeds may be made dormant by placing them under germinating conditions in blue light suggested that this kind of seed would provide satisfactory material for a study of certain aspects of dormancy in seeds. Studies have been made of the behavior of lettuce seeds under varied conditions of moisture, atmosphere, color of light, and integrity of the testa. Measurements of the absolute respiration have provided curves of the drift with time of carbon dioxide output, oxygen uptake, and of respiratory quotient. Experiments with substances that might induce dormancy and light-sensitiveness similar to that induced by blue light have been made. The bearing of the results obtained upon possible metabolic changes in the seed are discussed.The possibility that the observed effects of light upon seed germination are due to changes in the permeability of the seed coat induced by light is considered as untenable, but this does not exclude the fact that the seed coat is a restrictive agency to the free passage of oxygen, carbon dioxide, and other substances. Indeed, in any description of the probable metabolic state, this must certainly be considered. While it has not been possible to formulate a definite biochemical scheme to account for blue light effects, the experimental evidence suggests that 'carbon dioxide zymasis' may be promoted by blue light and that carbon dioxide may be one of the inhibiting factors. The blue light dormant condition is characterized by depressed respiration but without more disturbance of the equilibrium of the pre- and postglycolytic phases of respiratory metabolism than is found to be characteristic of uninhibited seeds as reported by other workers.The results of this research suggest that further elucidation of the phenomenon of dormancy should be sought in the direction of more extended studies of the respiration of dormant and non-dormant seeds.

ISSN:1923-4287    

DOI:10.1139/cjr48c-020

出版商:NRC Research Press    

年代:1948

数据来源: NRC