摘要:

Comparative tests of various powdered materials showed that well humified peat was superior to other preparations in maintaining the test bacteria in viable condition. Under the test conditions, sterilization of peat improved it as a medium for the maintenance of high numbers of viable cells. Neutralization was important, and more satisfactory following, than preceding, sterilization. Potassium carbonate was more suitable than sodium carbonate as neutralizing agent for promoting longevity of bacteria. Though peat allowed to dry immediately after inoculation did not permit the same high increase in bacterial numbers observed in peat kept at suitable moisture content, it was able to maintain large numbers of organisms in viable condition. Peat allowed to dry following the initial rise continued to support an increased load of living cells. After the initial increase at growth temperatures, peat stored at 4 °C. maintained numbers of bacteria better than at the higher temperature. Though immediate storage at 4 °C. resulted in a pronounced decline in numbers, subsequent removal to a temperature suitable for growth, even though delayed for as long as 12 wk., was followed by a rapid increase of bacteria to very high numbers.

ISSN:1923-4287    

DOI:10.1139/cjr47c-001

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

Pellets prepared from spongy, unhumified peat, were found to be well suited to the growth of the test organisms and were superior to pellets made from compressed, well humified peat. Sterilization had the effect of lowering somewhat the absorptive capacity of the spongy pellets and increased the buffering capacity. Neutralization was essential for sterilized pellets in maintaining viable organisms, though it was much less important with unsterilized peat. In contrast to powdered, humified peat, pellets of spongy peat showed to best advantage when allowed to become air-dry immediately following inoculation. In pellets subjected to immediate desiccation, the test organisms attained a much greater development, and were maintained in greater numbers than in peat kept moist or when desiccation was delayed.

ISSN:1923-4287    

DOI:10.1139/cjr47c-002

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

Comparative studies of the relative incidence of bacteria of different nutritional requirements in soil indicate that one of the most characteristic rhizosphere effects is the preferential stimulation of bacteria requiring amino acids for maximum growth. Organisms for which amino acids are either essential or stimulative were proportionately increased in the rhizosphere. No similar effect was noted with respect to bacteria responding to growth factors.The findings suggest, by indirect evidence, that the effect is to be ascribed to the excretion of amino acids by the growing plant. However, though this may be the chief factor, the preferential stimulation of the amino acid group of bacteria may be related to associative and antibiotic effects exerted by other bacteria, stimulated in the rhizosphere, observed to have different degrees of compatibility towards those responding respectively to amino acids and growth factors.

ISSN:1923-4287    

DOI:10.1139/cjr47c-003

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

A setback in rosette diameter and leaf number was observed in both first and second yearTaraxacum kok-saghyzplants at a definite stage in the plant ontogeny whatever the time of planting. This condition was evidently not entirely synonymous with the 'summer dormancy' of Russian workers as it did not involve complete loss of leaves, nor endure so long. The length of the 'dormant' period, which occurred at the time of reproduction and could be delayed, although not prevented by removal of flower buds, varied from about two to eight weeks. Various external modifications of environment had no appreciable effect on its onset. Watering and disbudding each increased the total fresh weight yield. Watering affected rosette diameter more markedly than it did root weight; disbudding affected both to approximately the same extent. Shading was not beneficial to growth.

ISSN:1923-4287    

DOI:10.1139/cjr47c-004

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

A survey has been made of the thiamin contents of Manitoba grown vegetables. These are of the same magnitude as of those grown elsewhere. The amounts vary with the vegetable and with the variety. There is often a wide range of values within a single variety. The effect of the district where grown is not significant. Cooking causes some destruction of the vitamin, but on an average boiled vegetables retain 63% of their thiamin, 23% is dissolved in the cooking water, and 14% is destroyed. Storage of raw vegetables does not decrease their thiamin contents appreciably. Canning causes losses, these varying with the vegetable and with the time of blanching and processing.

ISSN:1923-4287    

DOI:10.1139/cjr47c-005

出版商:NRC Research Press    

年代:1947

数据来源: NRC

摘要:

Coniothyrium olivaceumBon. was found to be the cause of a seedling blight of flax in 1945 and 1946 in Saskatchewan. Twelve out of 32 seed samples of flax from the 1945 crop selected for their low germination were carrying an average of 8% seed-borne infections. Leaf-spot lesions were found during late August, 1946. The wide distribution of the fungus suggests that it has been present in the province for some time. Hitherto, it has been reported on flax from the Argentine only. A strain of the same organism was present as a trace in one sample of sweet clover seed. Pycnidia develop abundantly in culture. The spores measure 7.5–10 (11.5)μ × 4.2–7.5 μ, averaging 9.1 × 6.0 μ, which is somewhat larger than the average for the species, but yet within the range limits. The disease is favoured by high moisture and probably by cool temperatures. It is one of the minor diseases on flax.

ISSN:1923-4287    

DOI:10.1139/cjr47c-006

出版商:NRC Research Press    

年代:1947

数据来源: NRC