摘要:

An alfalfa mutant with yellow cotyledons and yellow leaves is described. The few seedlings that live to maturity are dwarfs. The character is determined by a single recessive gene (Xantha-1 orX1) inherited tetrasomically. A histological study of the leaf morphology indicated that the tissues of the mutant have similar structure to those of green leaves. The plastids are well formed but take up stain weakly in comparison with the plastids in normal green leaves.

ISSN:0008-4026    

DOI:10.1139/b62-011

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Analysis of the growth of four trees from contrasting situations is extended to include the specific increment of cambial area, which is a measure of multiplicative growth of the cambium. This is found to correspond to radial growth, as measured by ring width, in the upper portion of the main axis and in the branches. Like ring width it exhibits the effects of intratree suppression and of a change from a condition of suppression to one of open growth. In the branches it is dependent on the position of the branch at the time of ring formation, and in those branches that are near the top of the crown, corresponding internodal rings show a higher specific increment of cambial area than those that are suppressed by overlying whorls. It is concluded that the factors controlling multiplicative growth of the cambium are essentially the same as those controlling radial growth.

ISSN:0008-4026    

DOI:10.1139/b62-012

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Segments of the first 10 millimeters of corn radicle tips have been analyzed in terms of invertase activity, cell number, fresh and dry weights, and sugar content. Invertase activity per cell increased 40-fold as the meristematic cell advanced to the stage of most rapid elongation, and again subsided as the cell ceased to elongate and entered the stage of maturation. In the growing cell, the concentration of sucrose remained low while that of reducing sugars increased fivefold.The corn radicle invertase was found to be a β-fructofuranosidase with aKmof 0.006 Mand a pH optimum of 4.6. Kinetic studies indicate that there is no change in the nature of the corn radicle invertase during cell growth. Equivalent activities of intact cells or segments and homogenates is consistent with the assumption that the enzyme is located outside the permeability barrier of the cells.

ISSN:0008-4026    

DOI:10.1139/b62-013

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

The present study was undertaken to investigate the soil respiration of different communities of the boreal forest region in the Gaspé Peninsula. The measurements were done with an absorption method which is described in detail. Productivity of the vegetation in the Gaspé Peninsula is obviously very low. Consequently soil respiration is also very low. Compared with the data obtained with the same method in the temperate zone of middle Europe, our data lie near the lower limit of these values.

ISSN:0008-4026    

DOI:10.1139/b62-014

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Specific differences ofAmbrosia artemisiifolia, A. trifida, andA. coronopifoliaare described and their present Canadian distributions are reported in detail.Ambrosiapollens, identified in fossil assemblages as eitherA. artemisiifoliaorA. trifidawith a few in the size range ofA. coronopifolia, were somewhat more abundant in late-glacial deposits than in younger postglacial sediments except the subrecent ones. It is only within the last 200 years that ragweeds have again become abundant in eastern Canada. The migration and spread of the three ragweed species in eastern and western Canada through postglacial time are discussed. There is evidence through pollen profiles thatAmbrosiaspecies existed further northward in Ontario than they do at the present time. In studying the presence and abundance ofAmbrosiapollen in surface samples, the authors showed that ragweed pollen can be transported through the atmosphere at least 375 miles from any known source.

ISSN:0008-4026    

DOI:10.1139/b62-015

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Cultures of 34 fungi were irradiated at 70° F under continuous exposure to near-ultraviolet light (3100–4000 Å) at 76 microwatts per cm2for periods ranging from 3 to 10 days. Sporulation was initiated or increased inAscochyta pinnodella, A. pisi, Alternaria chrysanthemi, A. tenuis, A. zinniae, Botrytis cinerea, Coryneumsp.,Epicoccum nigrum, Epicoccumsp.,Fusarium oxysporum, F. nivale, F. roseum, F. solani, Gliocladiumsp.,Helminthosporium avenae, Mycosphaerella pinodes, Ophiobolus graminis, Piricularia oryzae, Phoma herbarumvar.medicaginis, P. trifolii, Phomaspp.,Phyllostictasp.Pyrenochaeta terrestris, Septoria tritici, Stemphyllium botryosum, S. trifolii, Wojinowicia graminis, andVerticillium albo-atrum. H. oryzaeformed conidia only when irradiation was followed by a dark period.Kabatiella caulivoraandH. sativumsporulated as well in darkness as under irradiation. Sclerotia ofTyphulaspp. produced sporophores under a 12-hour dark, 12-hour ultraviolet light cycle at 41° F. When eight ultraviolet light-sensitive species were irradiated on various media, with few exceptions sporulation was stimulated irrespective of substrate. Irradiation of fungi under near-ultraviolet and artificial daylight fluorescent lamps stimulated sporulation equally well. When, however, near-ultraviolet and blue wave lengths were filtered from daylight fluorescent lamp radiation, sporulation was absent or much reduced in most species. Irradiation of colonies on a 12-hour dark, 12-hour ultraviolet light cycle caused zoning in the majority of species. Zoning was absent in colonies cultured under continuous exposure or under darkness.

ISSN:0008-4026    

DOI:10.1139/b62-016

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Being heterothallic,Puccinia graminisproduces haploid infections of two mating types the mycelial cells of which are uninucleate except for an occasional cell in which the nucleus has divided and in which the two daughter nuclei are still present. The pycniospores of both types of infection seem incapable of germination; but those of one type, when transferred to the upper surface of infections of the other type, fuse with the flexuous hyphae that protrude from the pycnia. By such fusions the pycniospore nuclei gain entry into the mycelia of the infections. When such transfers are made or when infections of opposite mating types coalesce to form compound infections, the introduced nuclei or their progeny migrate through the mycelia to the protoaecia of the infections, where they become conjugately associated with nuclei of the protoaecial cells. Meanwhile an occasional cell of the vegetative mycelium may become temporarily binucleate either by the division of its own nucleus, of by the passage through it of a migrating introduced nucleus or one of its progeny. Such a cell may become temporarily multinucleate by the division in it of one (or possibly both) of the daughter nuclei. In the protoaecium, conjugate associations are made possible by nuclear migration, in which activity both introduced and indigenous nuclei seem to be involved.

ISSN:0008-4026    

DOI:10.1139/b62-017

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Suspensions ofChlorella vulgaris, grown in synchronous culture, were pretreated in darkness for 45 to 225 minutes and illuminated in the presence of C14-bicarbonate with red, with red plus 4% of blue, and with blue light alone. The light intensities were so adjusted that the rate of photosynthesis (fixation of C14) was the same under the different conditions of illumination. The distribution of C14among the various compounds of the ethanol-soluble fraction was obtained using paper chromatography and autoradiography.After 5 minutes of photosynthesis, the incorporation of C14into aspartic acid was higher in the presence of red with supplementary blue light than in red light alone. At the same time the total radioactivity in glycine plus serine and in glycolic acid decreased. After 30 minutes of photosynthesis, blue light supplementary to red and blue light alone increased the total incorporation of C14into the amino acid plus organic acid fraction as compared with incorporation in red light. This was due mainly to an increase in the radioactivity of aspartic and glutamic acids, while at the same time the radioactivity in glycine and glycolic acid was reduced.The duration of dark pretreatment was an important factor in the 30-minute experiments. The effect of increased dark pretreatment was to lower the incorporation of C14into aspartic and glutamic acids when photosynthesis was carried out in red light, but the incorporation of C14into these acids was increased in the presence of supplementary blue light.It is concluded that the distribution of carbon among the products of photosynthesis is affected by the quality of light.

ISSN:0008-4026    

DOI:10.1139/b62-018

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Experiments were conducted on the factors involved in the induction of dormancy in wild oats. It was shown that when the supply of air reaching the embryo of imbibed seeds is restricted, changes occur in the caryopses so that when the seeds are subsequently dehulled and the caryopses exposed to air they are unable to germinate. Induction of dormancy is greater at 25 °C than at 7 °C. The site of the mechanism controlling induced dormancy is in the embryo or endosperm rather than in the seed coat or hulls. If dormant caryopses are punctured they germinate even when the wound is covered with lanolin or agar. Inhibitors were found in methanol extracts of both dormant and non-dormant caryopses, but it was concluded that they are not responsible for induced dormancy. An inhibitor which leaches from the hulls of wild oats completely stops growth of excised embryos but dormancy can be induced in the absence of hulls. Dormant caryopses absorb 2,3,6-triphenyl-tetrazolium chloride but are unable to reduce this dye. The mechanism of induced dormancy is discussed.

ISSN:0008-4026    

DOI:10.1139/b62-019

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

In an attempt to assess the microbiological activity characterizing the microflora associated with the roots of tomato plants, experiments were performed in which C14O2was supplied to their leaves and subsequently the soil was sampled for radioactivity. Several varieties of tomato were tested, some of which were resistant and some susceptible toVerticillium albo-atrum. Radioactivity in varying amounts was found in soil eluates, so that carbon fixed in photosynthesis must have passed out of the roots into the soil. Some of the radioactivity was released from the soil only by alcohol extraction and HCl hydrolysis and this fraction is considered to have been fixed in soil microorganisms as a result of their metabolic activity. The techniques used did not differentiate between the microbiological activities associated withVerticillium-resistant and -susceptible plants, although individual varieties seemed to be characterized by fairly definite patterns of radioactivity.

ISSN:0008-4026    

DOI:10.1139/b62-020

出版商:NRC Research Press    

年代:1962

数据来源: NRC