摘要:

A specific root rot of wheat and other cereals is described which is widespread over Saskatchewan, and occasions severe losses in some seasons. In early June, the outer leaves of the young plants become discolored, the number of tillers is reduced, growth delayed, and the yield considerably lessened. One of the chief diagnostic features is the presence of lesioned root tips containing oospores of the Pythium type. Although the disease is worst in a cool, wet spring, followed by warm, dry weather, the plants recover markedly when the remainder of the growing season is favorable. In preliminary work, "isolation strains" of various fungi from lesioned roots of field material collected in mid-summer failed to produce the disease under greenhouse methods of inoculation.A fungus belonging to the lower Phycomycetes, hitherto not described, was found associated with rootlet injury of wheat, barley, rye and maize seedlings grown in Regina clay soil from infested fields of southern Saskatchewan. Its life-history, morphology and physiological characters are given in detail; it is believed to be an obligate parasite which, under conditions favorable to its development, is capable of causing definite injury to wheat. It is not considered one of the major causes of browning root rot, but in the section where it is common it is likely one of the contributing causes in some seasons. It is regarded as belonging to the Ancylistaceæ, close to the genusLagenidium, but the erection of a new genusLagenais recommended. The binomialLagena radicicolahas been assigned to the fungus.More recently several "isolation strains" of Pythiaceous fungi have been secured from infected roots of wheat seedlings grown in soil collected from browning root-rot fields. A few of these in pot experiments in the greenhouse are shown to be definitely parasitic on the roots of wheat plants. There is some evidence that the particular root-rot concerned belongs to thePythiumroot-rot complex type.

ISSN:1923-4287    

DOI:10.1139/cjr30-014

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

Experiments were conducted in an effort to determine the cause of enhancement in baking quality previously observed on heat treatment of straight-grade flour not aged nor bleached. Heat treatment of straight-grade flour matured with agene (nitrogen trichloride), or of unaged fifth middlings flour (highly refined mill stream) did not result in any essential improvement in baking quality, and the unheated flours gave only a slight positive response to bromate. Similarly, ether extracted straight-grade flour gave no appreciable response to bromate and no significant improvement due to heat treatment. Germ added to fifth middlings flour markedly reduced its baking quality when determined by the basic procedure, as reflected in poorer handling qualities of the dough, and in the baked loaf by a decrease in loaf volume, underfermented characteristics, and coarse open texture. Increasing the fermentation time, addition of bromate, or heating the germ before admixture reduced the deleterious effects of the germ. The experiments indicate that response to bromate, and improvement of natural flour induced by proper heat treatment is associated with the presence of germ in the flour. Oxidation of certain germ constituents—presumably the phosphatides—is suggested as the primary change involved in such improvement. Addition of lecithin to middlings flour caused a marked response in loaf volume to the addition of bromate which is considered as indirect evidence that the phosphatides are involved. Heat treatment of germ induced a marked increase in the hydrogen ion concentration of aqueous extracts and a decrease in the iodine number of the ether extract. It is concluded from this series of investigations that heat treatment of flour is detrimental to gluten quality, but decreases the deleterious effect of germ present in the flour. Unaged flours containing low grade mill streams may show an enhancement in baking quality by heat treatment, but the improvement will not equal that induced by chemical improvers which apparently act primarily on the germ constituents.

ISSN:1923-4287    

DOI:10.1139/cjr30-015

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

Isopropylidene glycerol, prepared in neutral medium by the action of anhydrous copper sulphate as condensing agent, was methylated with silver oxide and methyl iodide; the product yielded only glycerol α-methyl ether on hydrolysis, thus proving the absence of any six-membered ketal in the condensation product of glycerol and acetone.The properties of both glycerol α- and β-methyl ethers have been carefully redetermined.A table of the isomeric acetals and ketals summarising their physico-chemical constants is given, in view of their usefulness as "type compounds" in investigations relating to fats, carbohydrates and polysaccharides.

ISSN:1923-4287    

DOI:10.1139/cjr30-016

出版商:NRC Research Press    

年代:1930

数据来源: NRC

摘要:

Freezing points for the system KCl–H2O are determined to 0.1° and 0.1% concentration over a range of concentrations including the eutectic. The solubility of potassium chloride in water at 25.22 °C. is measured. The heat capacities of a few rapidly and slowly frozen aqueous solutions of potassium chloride are investigated. The heat capacities of an approximately eutectic aqueous solution of potassium chloride are studied.Supercooling of aqueous solutions of potassium chloride is observed to be a constant factor under fixed cooling conditions, and its magnitude depends on the concentration of the solution. Aqueous solutions of potassium chloride, cooled rapidly to temperatures below the eutectic, are found to have approximately the same heat capacity values as those cooled slowly to the same temperatures. The heat of solution of potassium chloride at −10.7 °C. to form the eutectic concentration is calculated, and the relation between the phase rule diagram and heat capacities is discussed.

ISSN:1923-4287    

DOI:10.1139/cjr30-017

出版商:NRC Research Press    

年代:1930

数据来源: NRC