摘要:

A series of studies was made upon the coumarin content of various species, varieties and individual plants of sweet clover(Melilotus), determinations being made from different parts of the plant, at different stages of growth, and upon herbage dried by different methods. The conclusions drawn from the results of these studies may be summarized as follows:— (1) Coumarin content of the leaf and stem of sweet clover changes rapidly throughout the various stages of growth. (2) Wide variations in coumarin content exist between different species, between different varieties within a species and often between different individuals within a variety. (3) There is a marked relation between color of leaf and coumarin content. Plants possessing dark-colored foliage have invariably tested higher in coumarin content than those with foliage of lighter color. (4) The Alpha variety possesses a lower coumarin content than any other variety ofM.albustested. (5) The species,Melilotus dentatus, used in these tests, contained less than 0.01% of coumarin in the foliage and less than 0.05% in the mature seeds. For all practical purposes it may be regarded as coumarin-free. (6) Air drying or oven drying of sweet clover results in a heavy loss of coumarin from the leaves and marked changes in the coumarin content of the stems. (7) There is a definite correlation between the coumarin content of the leaf and of the mature seed in the materials used. (8) The coumarin content of the mature seed provides a reliable estimate of the coumarin content of the leaf of the plant. (9) Breeding results indicate the possibility of producing low coumarin varieties through inbreeding and selection.

ISSN:1923-4287    

DOI:10.1139/cjr36c-012

出版商:NRC Research Press    

年代:1936

数据来源: NRC

摘要:

Numbers ofRhizobium trifolii,Rh.leguminosarum,Rh.melilotiandAzotobacterwere determined at four-week intervals throughout a four-year crop rotation in three soils which had been receiving for twenty years no fertilizer, manure, and artificial fertilizer respectively. Though relatively small differences were noted in numbers ofRh.trifoliiin the three soils,Rh.leguminosarumandRh.melilotipersisted in much higher numbers in the two fertilized areas than in the unfertilized soil.Rh.trifolii, the only species with host plant in the rotation, occurred in much greater numbers than the other species, not only during and immediately following clover, but in succeeding years when little or no decline was noted. Apart from the effect of clover onRh.trifoliino significant effect of cropping was noted nor was seasonal influence important. Freezing of the soil for three months each year produced little or no effect on the numbers ofRhizobia.Numbers ofAzotobacterwere consistently higher in the unfertilized soil than in the fertilized areas. A seasonal effect was noted, with maximum numbers in March and minimum numbers in July, while freezing caused no noticeable diminution in colony count. The numbers ofAzotobacterfound were in all cases low and suggest that the part played by this organism in nitrogen fixation in field soil is still obscure.Rh.trifolii,Azotobacterand total numbers of bacteria by the plate method showed no relation with the productivity of the soils. Numbers ofRh.leguminosarumandRh.melilotishowed better agreement, though only in the case ofRh.melilotiwere relative numbers consistent with the soils in order of crop yields throughout the rotation.

ISSN:1923-4287    

DOI:10.1139/cjr36c-013

出版商:NRC Research Press    

年代:1936

数据来源: NRC

摘要:

A series of weed seeds comprising seven species and representing five families was studied to determine the effect of heat on subsequent germination. Lethal temperatures for 15 minutes' heating varied from 85° to 105 °C.The results indicate that there is a critical temperature below which moderate periods of heating have little effect on viability. At higher temperatures the germinating power falls off rapidly.

ISSN:1923-4287    

DOI:10.1139/cjr36c-014

出版商:NRC Research Press    

年代:1936

数据来源: NRC