摘要:

In a small replicated field trial, percentage sugar and root weight were negatively correlated in both diploid and triploid individual beets, but the decreases in percentage sugar for every 100-gm. increase in root weight differed significantly, being on the average 0.34% for the diploids and 0.17% for the triploids. As root weight increased beyond 900 gm. the yield of sugar per 100 gm. of root weight increased more rapidly in the triploids than in the diploids. Under the conditions of this test, triploid beets exceeded the diploids in root weight by 12.2%, in yield of sugar per beet by 14.9%, and in dry top weight by 17.8%. The triploids exceeded the diploids in area index of the leaves by 34.4% and in area index of the stomata by 42.6%.

ISSN:1923-4287    

DOI:10.1139/cjr40c-028

出版商:NRC Research Press    

年代:1940

数据来源: NRC

摘要:

Indolylbutyric acid and oestrone, separately and in combination in a series of talc dusts, were applied to dormant cuttings ofLonicera tartarica. Indolylbutyric acid treatment, averaged over all oestrone treatments, increased the number of cuttings rooted, the number and length of roots per rooted cutting, the mean root length, and the green weight of leaf produced by the dormant cuttings. The average effect of oestrone on these responses was depressive throughout. Oestrone tended to offset the beneficial effects of the plant growth stimulating chemical, excepting the combination of 100 p.p.m. of each which increased root length. Oestrone alone did not reduce either the number or lengths of root per rooted cutting.The results indicated that the number and length of roots and the green weight of leaf produced are more sensitive responses for demonstrating differences due to indolylbutyric acid concentration in talc than is the percentage of cuttings rooted.

ISSN:1923-4287    

DOI:10.1139/cjr40c-029

出版商:NRC Research Press    

年代:1940

数据来源: NRC

摘要:

The effect of wheat, oat, and barley straw, composted with soil, on the development of disease on the basal parts of wheat seedlings was studied in a series of greenhouse experiments during three seasons. The pathogens used wereOphiobolus graminisSacc.,Helminthosporium sativumP. K. and B., andFusarium culmorum(W. G. Sm.) Sacc. The wheat-straw composts were distinctly more favourable to the development of disease than the composts of either oat or barley straw. The least injury occurred on seedlings grown in composts of oat straw. It is suggested that the micro-organisms associated with the decomposition of oat straw bring about some degree of biological control of the plant pathogens also present.Although the amount of straw applied sometimes influenced severity of disease, the effects were not consistent from planting to planting. Apparently the actual carbon to nitrogen ratio had less effect upon disease development than did the chemical nature of the straw.The kind and amount of straw in the composts also influenced seedling vigour. This vigour was, in general, inversely proportional to the degree of infection.The introduction of a short fallow period between plantings decreased infection somewhat and increased vigour.The pathogenicity of the artificial inoculum added at the first planting was practically vitiated before the second planting. Subsequently, the infection ratings tended to increase and were about the same as those in the uninoculated series.

ISSN:1923-4287    

DOI:10.1139/cjr40c-030

出版商:NRC Research Press    

年代:1940

数据来源: NRC

摘要:

The microbial population in the rhizosphere of wheat, oats, alfalfa, and peas was studied and the relative abundance of different types of micro-organisms recorded. By means of the plating method it was found that bacteria and actinomycetes were 7 to 71 times greater in the rhizosphere than in the soil distant from the roots, whereas fungi were but 0.75 to 3.1 times more numerous.Different varieties of plants affected the activity of the various groups of soil micro-organisms differently. Thus fungi were more numerous in the rhizosphere of oats, and bacteria in the rhizosphere of alfalfa. Seventeen genera of fungi were represented in isolates from the rhizosphere of seedlings and the soil distant from the roots. However, no marked difference was observed in the types isolated from the rhizosphere of different varieties of seedlings. A fungus isolated from the rhizosphere of alfalfa proved to be a new species and the genusSpiculariaPersoon was amended to include it.

ISSN:1923-4287    

DOI:10.1139/cjr40c-031

出版商:NRC Research Press    

年代:1940

数据来源: NRC

摘要:

The distribution ofPrunusspecies in Eastern Canada is of definite economic significance since these species serve as secondary hosts for leaf hoppers and aphids, which are vectors of important virus diseases.A key is presented for the determination of the following native and naturalized species:Prunus spinosa,insititia,domestica,americana,nigra,Persica,pumila,avium,Cerasus,mahaleb,pennsylvanica,serotina,Padus, andvirginiana. The detailed distribution of these species is outlined through the citation of herbarium specimens and Canadian Weed Survey records, the ranges of the more important species being mapped.Cultivated and naturalized species are considered to be of little significance in disease transmittal. In potato-growing regions the choke cherry (P.virginiana) which frequents fence-rows is probably the most important species, although the bird cherry (P.pennsylvanica) may also be important on light sandy soils.

ISSN:1923-4287    

DOI:10.1139/cjr40c-032

出版商:NRC Research Press    

年代:1940

数据来源: NRC