摘要:

Significant negative inter-varietal correlation coefficients between steeping time and barley saccharifying (− 0.706), malt saccharifying (− 0.814), starch-liquefying (− 0.954), autolytic diastatic (−0.937), and proteolytic (−0.822) activities are shown to be dependent on the same fundamental barley properties as similar positive coefficients between these activities and salt-soluble barley nitrogen. Barley and malt saccharifying and proteolytic activities are equally associated with both salt-soluble nitrogen and steeping time, but starch-liquefying and autolytic diastatic activities are more closely associated with the latter property. Significant inter-varietal correlation coefficients were obtained between liquefying, autolytic, and proteolytic activities and malt extract and malting loss. Partial correlation studies indicate that only the simple coefficient between malting loss and proteolytic activity (0.915) represents a real relation independent of salt-soluble nitrogen and steeping time.With the exception of autolytic diastatic activity, highly significant intravarietal correlation coefficients were obtained between malt extract and enzymatic activities. Partial coefficients, independent of total nitrogen, show that proteolytic, liquefying, and autolytic activities are associated with malt extract. Simple intra-varietal correlations of malting loss with barley saccharifying (0.671), malt saccharifying (0.702), and proteolytic (0.701) activities reflect mainly the effects of total nitrogen. Enzymatic activities are negatively correlated with steeping time within as well as between varieties, and partial correlation coefficients suggest a real relation between liquefying activity and steeping time.

ISSN:1923-4287    

DOI:10.1139/cjr40c-006

出版商:NRC Research Press    

年代:1940

数据来源: NRC

摘要:

Comparative studies of the relative incidence of bacterial types occurring in the rhizosphere of different plants and in control soils indicated that the qualitative nature of the soil microflora is markedly influenced by the growing plant. In the rhizosphere Gram-negative rods are proportionately increased while Gram-positive rods, coccoid rods, and spore-forming types are relatively less abundant.The majority of bacteria isolated from soil by non-selective plating are forms included in the family Proactinomycetaceae (Jensen's classification). Of these by far the largest group consists of members of the genusCorynebacterium. In the rhizosphere proactinomycetes as a whole are relatively less abundant, with theCorynebacterium(non-motile) group likewise depressed. However, closely related motile forms classed asMycoplanaare preferentially stimulated.In the rhizosphere the bacteria show definitely greater physiological activity than in soil distant from the plant. Not only is there a notably greater proportion of motile forms, and a pronounced increase in the incidence of chromogenic types, but also a higher incidence of liquefying bacteria and of those able to affect glucose.A comparison of the rhizosphere of certain plant varieties resistant and susceptible respectively to soil-borne disease showed differences of a qualitative nature in the bacterial flora suggestive of a greater "rhizosphere effect" in the case of the susceptible varieties studied. Results point to the possibility that resistance may be associated with a selective action of root excretions on the saprophytic soil microflora.

ISSN:1923-4287    

DOI:10.1139/cjr40c-007

出版商:NRC Research Press    

年代:1940

数据来源: NRC

摘要:

Evidence has been obtained through crossing and selfing studies that some physiologic races of oat stem rust contain both homozygous and heterozygous lines, the latter when selfed tending to produce races more virulent than the selfed race. In crosses between races, the less virulent characteristics are generally dominant so that the hybrid race is often identical with the less virulent of the two parent races. Selfing studies and crosses therefore indicate that the more virulent characteristics of oat stem rust are recessive traits. Reciprocal crosses between physiologic races suggest that the cytoplasm, as well as the nucleus, contributes to the inheritance of certain pathogenic characters.In crosses between races of normal (red) and orange uredial colour, the red colour has invariably proved dominant, the progeny being indistinguishable in colour from the normal parent.Two selfing studies of Race 3 carried out with the same telial material at an interval of more than four years have provided evidence of a genetic change presumably brought about through the ageing of the teliospores. In the first selfing, no abnormalities were observed in the infections on the barberry. In the second selfing, about half of the infections developed pycnia and pycnial nectar, while the remainder appeared as small, round, necrotic areas showing no indication of even rudimentary pycnial formation.

ISSN:1923-4287    

DOI:10.1139/cjr40c-008

出版商:NRC Research Press    

年代:1940

数据来源: NRC