摘要:

Crosses made in all possible combinations between varietiesTritici,Secalis,Avenae,Agrostidis, andPoaeofPuccinia graminisPers. have shown the existence of considerable intersterility in crosses between some of the varieties. Fertility was relatively high in crosses between vars.TriticiandSecalis,AvenaeandAgrostidis,AvenaeandPoae, andAgrostidisandPoae. Fertility was much lower in crosses between vars.TriticiandAvenae,SecalisandAvenae, andSecalisandPoae. In crosses between certain pairs of varieties the degree of fertility varied according to the direction of the cross.Tritici×Agrostidis,Tritici×Avenae,Tritici×Poae,Secalis×Agrostidis, andSecalis×Poaecrosses succeeded much better than the reciprocal crosses. Sporidia from theF1teliospores ofTritici×Secalishybrids infected barberry with the production of normal pycnia and aecia. Sporidia ofTritici×AvenaeandSecalis×Avenaehybrids produced, on barberry, infections with few pycnia and these excreted little nectar; no aecia were formed but urediospores and teliospores were occasionally produced in old infections. Generally, anF1hybrid rust possessed a wider host range than did either of the parent varieties; but the pathogenicity of the hybrid on a given host was less than that of the parent variety that attacked that host. In hybrids of varieties that differed markedly in urediospore size the urediospores of theF1hybrid rusts were intermediate in size between those of the parents. The pathogenic characteristics of theF2(uredial) generation were studied only inTritici×Secalishybrids. Variation in pathogenicity was rather restricted. The races isolated were moderately pathogenic to barley and weakly pathogenic to wheat and rye.

ISSN:1923-4287    

DOI:10.1139/cjr49c-004

出版商:NRC Research Press    

年代:1949

数据来源: NRC

摘要:

A study of the effect of temperature on the infection of wheat byUrocystis triticiwas made using Petri dishes in incubators held at various temperatures from 9° to 26 °C. The seedlings were transferred to pots as soon as the plumules broke through the coleoptiles. The percentages of infection obtained at various temperatures were as follows:—10.8% at 9° to 14 °C., 13.8 at 16°, 21.1 at 18°, 26.1 at 20°, 15.7 at 22°, 6.9 at 24°, and 3.0% at 26 °C. Growth studies of three geographical isolates ofU.triticiwere made on 12 different artificial media. Cultures were obtained by plating bits of disinfected unbroken, fresh, smutted plant tissue. The smut organism was found to be culturable on various media, though its growth rate was rather slow. The three isolates grew well on potato dextrose agar, Thaxter's hard agar, 4% sucrose potato agar, wheat seedling agar, and Czapek's synthetic medium, and were found to differ characteristically on five different media.

ISSN:1923-4287    

DOI:10.1139/cjr49c-005

出版商:NRC Research Press    

年代:1949

数据来源: NRC

摘要:

Fourteen species of the commoner marine algae of Nova Scotia have been analyzed for their content of water, nitrogen, ash, calcium, phosphorus, and iron. These algae are remarkable for their consistently high ash content. The minimum value was 12.3% inAhnfeltia plicataand the maximum 45.4% inEnteromorpha intestinalis. The average content was 24.9%. Differences in composition have been observed between the green, red, and brown classes or algae.

ISSN:1923-4287    

DOI:10.1139/cjr49c-006

出版商:NRC Research Press    

年代:1949

数据来源: NRC

摘要:

In the present study of trout streams in mountainous headwater regions, the term "streamside cover" includes a wide strip of forest vegetation on both sides of the stream, rather than a narrow fringe of plants at the water's edge. Undisturbed stream margins in virgin spruce woods are compared with those in adjacent areas recently logged over in relation to shade production, water conservation, and protection against stream-bank erosion. Heavy, indiscriminate cutting along the stream margins has removed almost all the good shade producing trees, eradicated by exposure and mechanical means the former water conserving ground vegetation, and caused serious damage to the stream itself by logging operations. As the result of this study, the prohibition of all cutting along wide strips on both sides of the trout stream is strongly recommended in order to maintain suitable environmental conditions for trout and to preserve aesthetic values of fishing areas.

ISSN:1923-4287    

DOI:10.1139/cjr49c-007

出版商:NRC Research Press    

年代:1949

数据来源: NRC

摘要:

The soluble proteins of pea meal were extracted with phosphate buffer and fractionally precipitated with ammonium sulphate. An electrophoretic analysis of each preparation was made, and the amount and mobility of each component determined. There are probably three distinct components in the pea protein and one of these at least is a protein system, which tends to separate into further components under some conditions. The components were not at all well separated by fractional precipitation, and the separation was decidedly affected by the method of preparation and the pH of the precipitation medium.

ISSN:1923-4287    

DOI:10.1139/cjr49c-008

出版商:NRC Research Press    

年代:1949

数据来源: NRC

摘要:

The molecular characteristics of gluten in sodium salicylate solutions have been studied by means of diffusion and electrophoretic techniques. The results of the observations indicate that gluten in sodium salicylate is electrostatically homogeneous with a high mean negative valence of 34 and therefore a high surface charge density. The isoelectric point of gluten in this dispersing agent is below pH 4.0. This low value of the isoelectric point and the high valence of the protein molecule is probably due to selective adsorption of salicylate ions on gluten. The particles in the fraction of gluten molecularly dispersed in 0 5 μ sodium salicylate are prolate ellipsoids of revolution of the order of 25 Å in diameter and 400 to 450 Å long. These are mean values as the molecularly dispersed particles are not uniform in mass. When they are aggregated it is side by side association rather than end to end. The density of dehydrated gluten is 1.291 gm. per cc. Qualitative evidence is given for the view that the degree of hydration of gluten particles is probably not great.

ISSN:1923-4287    

DOI:10.1139/cjr49c-009

出版商:NRC Research Press    

年代:1949

数据来源: NRC

摘要:

Uniform conditions for the culture of the plants and for conducting starvation–respiration experiments upon the first seedling leaves permit the recapture and hence thorough investigation, of transitory physiological states. A standard sample of isolated, mature leaves, so produced and starved, is shown to be heterogeneous when tested by the tempo at which the tissues in different parts of the sample pass through the color changes that accompany starvation. These are correlated with respiration. Interleaf variation in tempo is relatively small. Intraleaf variation is maximal and the leaf is polarized at isolation but a complex redistribution of tempo within each leaf brings about depolarization and diminishes intraleaf heterogeneity as starvation progresses. The respiration of such a starving sample follows a time course of characteristic pattern, all the prominent features of which have their homologues in the corresponding patterns of younger and older leaves. The homologous characters undergo gradual modification with ontogeny. The respiration of the unstarved isolated leaf is very high and falls rapidly during growth but is low and declines slowly in maturity and senescence. At the transition from growth to maturity a slight, temporary rise in respiration occurs.

ISSN:1923-4287    

DOI:10.1139/cjr49c-010

出版商:NRC Research Press    

年代:1949

数据来源: NRC