摘要:

The nutrient content of the humus and of some of the plants characteristic of different site classes has been studied. Analyses carried out on fresh healthy leaf material from typical forest plants indicated no differences within a given species that could be related to site quality. Available nutrient content of the A0horizon collected in the same environment is, however, closely related to the productivity of the sites. It seems, therefore, that the differential accumulation of nutrient elements in the cells of the forest plants studied depends upon the inherent properties of the species rather than on the quantity of available nutrients in the humus on which they grow.

ISSN:0008-4026    

DOI:10.1139/b58-018

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

Regulatory effects of auxin on mitosis and DNA synthesis were studied in lateral bud apices ofTradescnntia paludosa.In axillary buds inhibited by the terminal bud, mitoses were absent in a group of cells constituting the initials of tunica and corpus within the apex. The DNA (Feulgen) content of inter-phasic nuclei in this "zone of inhibition" was uniform and no greater than that characteristic of diploid telophase (2C), despite differences in nuclear volume. In subapical bud tissues, mitoses occurred at a low rate. Upon removal of the vegetative shoot tip, this mitotic rate was increased and the previously inhibited nuclei within the apes underwent DNA doubling to 4C, then entered prophase. These results indicate that the interphase synthesis of at least one chromosomal substance (DNA) is under auxin control. Evidence is presented that mitosis is not directly inhibited by this hormone. Naphthalene acetic acid was found to substitute for natural auxin in the inhibition of DNA synthesis.

ISSN:0008-4026    

DOI:10.1139/b58-019

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

Wheat seedlings were grown in sand culture in 1 qt. crocks. Maleic hydrazide (10 mg. per crock per day) prevented flowering and increased the oxygen consumption per unit dry weight of the first leaves by 20 to 50%, but did not alter the C6/C1ratio, which was measured by incubating leaf disks with glucose-6-C14and glucose-1-C14. Indoleacetic acid (0.5 mg. per crock per day) increased oxygen uptake by only 10 to 15%, but stimulated flowering and apparently lowered the C6/C1ratio. The C6/C1ratio of leaf disks was approximately halved by 2 hours pretreatment with 5.0 and 8.3 p.p.m. of indoleacetic acid, mainly because of a decrease in the recovery of C6.The results are discussed briefly in relation to the effect of obligate parasites in increasing the indoleacetic acid content and in lowering the C6/C1ratio of susceptible cereal leaves.

ISSN:0008-4026    

DOI:10.1139/b58-020

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

Crown bud rot is widespread in irrigated alfalfa stands in southern Alberta.Rhizoctonia solaniKühn,Fusarium roseumLink sensu Snyder & Hansen, andAscochyta imperfectaPeck acting alone or in combination produce brown to black lesions on the crown buds of plants in their second and subsequent years of growth. The host plant is most susceptible to the disease in early spring after winter dormancy. Soil temperatures above 16 °C. appear to reduce disease development. Relative occurrence of species isolated from infected buds indicate a succession of fungi.F.roseumis the predominant isolate until the third year of alfalfa growth when its numbers are approximately equalled byR.solani. The latter then decreases in prevalence possibly because of the antibiotic action of saprophytic species ofTrichodermaandPenicillium.F.roseummaintains about the same degree of activity throughout the growing season whereasR.solanigenerally appears most frequently in summer-sampled alfalfa andA.imperfectain spring samples.

ISSN:0008-4026    

DOI:10.1139/b58-021

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

Xanthophyllous is a dominant yellow-leafed mutant; the genotypeXa Xais lethal in either the seed or the very early seedling stage, while the genotypeXa xais viable but reacts differently to light intensity than does the normalxa xaplant. The 1: 2: 1 ratio is never realized because less than half the lethals appear as seedlings. The 2: 1 ratio is affected by germination so that under good conditions for germination a 2: 1 ratio is obtained, but under poor conditions the ratio may approach 1: 1. Maximum likelihood formulae are given for calculating linkage when one gene is a dominant with recessive lethal effects, and it is shown that the simple product moment method gives similar results for these data.Xais in linkage group VII (chromosome 10), and its lethal effect disturbs the monogenic ratios of all genes in this group. The following crossover values between these genes andXaare found:H44.5%,pe50%,t35.5%,tv31.7%, andag46.5%.Under standard growing conditions the pigment concentrations of xanthophyllous contrasted with green is: chlorophyll, 790 instead of 3240 μg./g.; xanthophyll, 54 instead of 211 μg./g.; and carotene, 60 instead of 130 μg./g. Both green and yellow plants, when grown under various intensities and spectral compositions of light, have different responses. Green plants make only limited response to changes in light intensity, whereasXa xaplants become green and cannot be distinguished fromxa xaplants. From 600 to 8000 ft-c. theXa xaplants show a linear trend of decreasing pigment (increasing yellowness) with increasing light intensity. The hypothesis is advanced thatXa xaplants make as much pigment as do green ones, but a light-dependent reaction breaks down the pigments faster than they are being formed.

ISSN:0008-4026    

DOI:10.1139/b58-022

出版商:NRC Research Press    

年代:1958

数据来源: NRC

摘要:

Only four species ofTritomariaSchiffn. have been described, all found in cold to boreal regions of the northern hemisphere. Of these, onlyT.quinquedentata(Huds.) Buch has been known from the arctic portions of eastern Canada. The range of this species in Canada east of the 100 meridian is tabulated, and two varieties, var.turgida(Lindb.) Weim. and var.grandiretisBuch and Arnell, are described from the same area. The latter variant is here first recorded from North America: it is presumably a polyploid, possessing larger cells and more numerous oil-bodies.T.heterophyllaSchuster is described from materials from northernmost Ellesmere Island. It is allied toT.scitula, from which it differs in purplish pigmentation, broader than long leaves, and spinose-dentate perichaetial bracts. The last peculiarity serves to differentiate it from all other species of the genus. A key to all of the species and varieties, all known from eastern Canada, is given.

ISSN:0008-4026    

DOI:10.1139/b58-023

出版商:NRC Research Press    

年代:1958

数据来源: NRC