摘要:

Fifty actinomycetes, isolated from a variety of soils on the basis of their antibiotic activity againstEscherichia coli, were tested against different soil bacteria. Wide variations were noted in susceptibility of the test organisms to the antagonists. Actinomycetes with the most intense antibiotic activity were able to act upon the greatest number of bacterial species.

ISSN:1923-4287    

DOI:10.1139/cjr48c-034

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

Gaseous exchange by growing tomato fruits is localized in a ring of lenticel tissue that encircles the receptacle and is covered by the calyx. The size of this annular lenticel varies with the size of the fruit.Growth of the fruits of the variety Grand Rapids includes a phase of residual mitotic activity that persists for approximately one week after setting. Cell division is reduced in dwarf or laggard fruits, which are examples of natural parthenocarpy. Under seasonal conditions that are favorable for natural setting, application of 0.2% indolebutyric −50 p.p.m. β-naphthoxyacetic acid to pollinated flowers markedly increases the number and size of fruits obtained with the Marglobe but not with the Grand Rapids variety. The locular pulp of parthenocarpic fruits usually remains green during vine ripening. The green color is largely imparted by chloroplasts that are concentrated in the vicinity of the vascular strands leading to the aborted ovules.

ISSN:1923-4287    

DOI:10.1139/cjr48c-035

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

An investigation of the salt requirements for fluorescin production has been carried out, and the mineral balance for maximum fluorescin production determined. Employing ammonium succinate as a source of nitrogen, the ions PO4, Mg, SO4, and Fe have been found essential to the formation of the pigment. Optimum production of fluorescin resulted when 0.01% magnesium chloride, 0.06% dipotassium hydrogen phosphate, 0.005%, potassium sulphate, and 0.000005% (0.05 p.p.m.) ferric chloride were used.The influence of high concentrations of Mg and SO4ions in the presence of varying concentrations of iron with ammonium succinate as the source of nitrogen on the formation of both fluorescin and pyocyanin has been determined.Fluorescin production has been demonstrated to depend primarily upon the concentration of sulphate, iron, and magnesium in the medium. The concentration of iron required has been shown to be of paramount importance. Increasing the amounts of either SO4or Mg did not bring about the pronounced stimulation of fluorescin production as was evidenced in the case of pyocyanin.

ISSN:1923-4287    

DOI:10.1139/cjr48c-036

出版商:NRC Research Press    

年代:1948

数据来源: NRC

摘要:

The genusBrassicawith its numerous cultivated strains and weed varieties presents a difficult problem to the seed analyst. A solution is attempted in this paper. Peculiarities of seed color, shape, and histology have been used wherever possible as diagnostic characters. In cases where these were found to require verification the characters of the young seedlings were used to supplement them. It has been found possible to distinguish the seeds or seedlings of plants so closely related as to be separated in adult form only by differences in the depth of the yellow color in their roots and blossoms. Care has been taken to test the material for authenticity and to make sure that the seed and seedling characters chosen are closely linked in heredity with distinguishing characters of the species and varieties. A key for the identification of seeds of known varieties ofBrassicahas been evolved.

ISSN:1923-4287    

DOI:10.1139/cjr48c-037

出版商:NRC Research Press    

年代:1948

数据来源: NRC