摘要:

Histochemical tests onPinus radiatashoot apices throughout the growing season showed marked changes in cell constituents. Reserve proteins and lipids were high in dormant embryos. Following imbibition, starch occurred throughout the apex and tannins were evident after the cotyledons emerged from the seed coat. Intensity of stains for DNA, RNA, and nucleohistones increased first at the flanks of the apex. At 84 days DNA, RNA, and histones displayed a zonate distribution pattern. Total proteins and carbohydrates were distributed fairly uniformly.The distribution of enzyme activity also varied. Initially acid phosphatase (AP) and succinic dehydrogenase (SDH) activities were high throughout the apex. A decrease of AP and SDH activity in the apex preceded epicotyl elongation. At 84 days AP activity differed in various regions of the apex; SDH was fairly uniform throughout the central, apical, and peripheral zones. Staining for peroxidase was evident first around aleurone grains and along cell walls after imbibition. With the onset of needle formation, staining was concentrated in subsurface cells. At 84 days peroxidase activity was concentrated in subsurface cells of the peripheral zone and in the rib meristem.The results of this study indicate that the full apex is metabolically active during vegetative growth and all regions are probably involved in the determination of vegetative form.

ISSN:0008-4026    

DOI:10.1139/b73-061

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

The total fatty acids of cultured cells from 11 cell lines (nine species of plants) were determined. Linoleic acid was the most abundant fatty acid in most of the cultures (16.3%–60.9%, average = 39.4%). Palmitic acid varied from 19.1% to 54.8%, average = 28.4%. Stearic and oleic acids were usually less than 10%, with averages of 7.4% and 4.7% respectively. Linolenic acid varied from 3.5% to 19.8% in nine of the cell lines but morning glory (Ipomoeasp.) and soybean (Glycine max) contained 35.7% and 51.2% respectively. Arachidic acid was either absent or present in amounts of less than 5%.The total fatty acid patterns of various parts ofIpomoeasp. andGlycine maxplants were compared with those of the cultured plant cells. The fatty acid composition of the leaves and of the cultured cells were quite similar in both plants. The lipids found in tissue culture cells are not necessarily comparable to those of the part of the intact plant from which the cell culture was established.

ISSN:0008-4026    

DOI:10.1139/b73-062

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

In this paper, the authors deal with the morphological features of 10 abnormal branches of honeysuckle. The studied forms are of two different types. The first is illustrated by five specimens collected on a single hybrid bush calledLonicera nigra×orientalis. All of these show unusual union between restricted portions of different leaves. The arrangement of the fused parts permits one to infer that gamophylly, in this example, results indubitably from a real ontogenetic (postgenital) union. Concaulescence is the second kind of anomaly, shown in the samples from various cultivars belonging to theLonicera tataricacomplex. The occasional occurrence of accessory serial buds between the concrescent axes suggests that ontogenetic fusion could give rise also to such structures. In some particular instances, however, it is possible that unusual intercalary growth is combined with the first process.

ISSN:0008-4026    

DOI:10.1139/b73-063

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Extractive changes that occur in the sapwood of lodgepole pine (Pinus confortaDougl. var.latifoliaEnglm.) in response to attack by the bark beetle (Dendroctonus ponderosaeHopk.) and associated microorganisms were studied. The most striking change was a large increase in total terpene to levels well above that normally observed in sapwood or heartwood. Free acids, phenolics, and neutral components increased to a final concentration about the same as that in heartwood, but at a much slower rate than terpenes. Free sugar levels decreased. With the single exception of β-phellandrene no unusually high or unusually low levels of any one compound were observed in the wound response. All components found in the wound response were normal constituents of heartwood.

ISSN:0008-4026    

DOI:10.1139/b73-064

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Plants ofCosmos bipinnatusCav. ‘Sensation’ (a quantitative short-day plant) were grown under continuous conditions favorable or unfavorable for flowering, and some plants in each group were treated with gibberellic acid (GA3). Floral apices ofCosmosare formed by the transition of previously vegetative apices. The vegetative apex shows a cytohistological zonation pattern superimposed upon a tunica–corpus organization. The vegetative apex passes into an intermediate stage presumed typical of many plants held under non-inductive conditions. This stage is marked by many cytological features characteristic of both reproductive and vegetative apices but leaves continue to be produced. The presence of the intermediate stage accounts for conflicting results obtained in physiological studies since there is great variation in response rate depending on age of plant and the stage of the apex at the start of an experiment. This stage is followed by a typical transitional stage marked by an increase in RNA content, increased mitotic activity, and a change in zonation. Elongation of the apex and internodes occurs followed by initiation of the involucral bracts and floret primordia, marking the beginning of the prefloral and inflorescence stages respectively.GA3specifically inducesCosmosto flower under non-inductive conditions thereby influencing floral initiation in a facultative short-day plant. Microscopic examination of the rate of apical transition revealed that GA3substituted effectively for short days but was not as efficient an inducer as were short days.

ISSN:0008-4026    

DOI:10.1139/b73-065

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

The Old Crow Plain, northern Yukon Territory, Canada, is a large flat lowland consisting of basin-fill sediments of Late Quaternary age. The modern Arctic treeline passes across the northern tip of the lowland, and much of the vegetation consists of tundra and shrub tundra, with scattered groves of spruce mainly on alluvial deposits. Steep scarps have been exposed by the downcutting of the Old Crow River in these basin-fill sediments, and good exposures of Late Quaternary sediments are available for investigation. Samples from six of these exposures were analyzed for pollen. Although many parts of the sections were barren, it has been possible to derive pollen diagrams with discrete pollen zones for the six sections, and four pollen assemblage types have been identified. Their occurrence in the stratigraphie sequence suggests the following pattern of pollen stratigraphy: the lowermost sedimentary units, probably deposited early in the interstadial following an Early Wisconsin glaciation, are of pollen assemblage types III (Glumiflorae–herb) or IV (Betula–herb), both indicative of tundra vegetation; the middle levels of the sediment show, consistently, pollen spectra of type II (Picea–Betula–Glumiflorae–herb), indicating forest groves with tundra, quite similar to the modern vegetation. The sediment underlying the Upper Glaciolacustrine Unit (correlative, according to Hughes (1969), with the Classical Wisconsin Stadial) yields pollen assemblage type III (Glumiflorae–herb), which is interpreted as indicating a rich and varied tundra. These vegetation reconstructions are consonant with a tentative palaeoclimatic interpretation in terms of a tripartite interstadial climate showing severe tundra climate – milder forest or forest–tundra climate – severe tundra climate. Two of the sections have incomplete pollen stratigraphy for the uppermost postglacial silts and peats. They suggest that vegetation similar to the present day became established in the Old Crow Plain in mid-postglacial time.

ISSN:0008-4026    

DOI:10.1139/b73-066

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Rhabdogloeopsis balsameae(J. J. Davis) Petrak andRhabdogloeum pseudotsugaeSydow, the type species ofRhabdogloeopsisPetrak andRhabdogloeumSydow respectively, are redescribed and illustrated. Emended generic diagnoses are provided.

ISSN:0008-4026    

DOI:10.1139/b73-067

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Four species of mosses, all in the genusOrthotrichum; 1 species of hepatics; and 16 species of lichens compose the foliicolous bryophyte and lichen flora ofThuja plicataL. leaves in certain areas of western British Columbia. This is the first report of foliicolous mosses and hepatics for North America, north of the tropical and subtropical regions of the southeastern United States. The taxonomy of the four species ofOrthotrichumis discussed and a key given differentiating the species.All of the species that have been found onThujaleaves except perhapsCatillaria bouteilleiare facultative foliicolous species and occur on leaves, only in scattered areas of northwestern North America. Two taxa of lichens,Catillaria bouteillei(Desm.) Zahlbr. andCetrelia cetrarioides(Del. ex Duby) W. Culb. & C. Culb. (perlatolic acid strain) are reported as new to Canada.

ISSN:0008-4026    

DOI:10.1139/b73-068

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

In situmeasurements of CO2assimilation byDryas integrifoliaat different stages of development and under different environmental conditions were made on Devon Island, Northwest Territories.Dryascan fix CO2in excess of respiration over a 24-h period under conditions of clear nights and cloudy days. The maximum net assimilation rate measured was 4.2 mg g−1dry weight h−1. The maximum amount of CO2fixed in 24 h was 61.54 mg g−1dry weight. Maximum net assimilation occurred at 8 to 10 °C leaf temperatures. Positive net assimilation occurred at 1 °C leaf temperature. Light compensation was shown to be less than 0.04 langley min−1. Leaf temperatures were always greater than ambient. The maximum leaf temperature measured was 39 °C. Net assimilation rates appear to decrease as the season progresses.

ISSN:0008-4026    

DOI:10.1139/b73-069

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Ballistospore discharge inTilletiopsis minorNyland was studied in a growth chamber under various conditions using a Kramer-Collins Spore Sampler. Sporulation occurred on leaves ofAltheanaturally infected withPuccinia malvacearum, on inoculated healthy leaves ofAlthea, and on 11 other hosts. Under alternating dark (12 h, 90–94% relative humidity (RH)) and light (12 h, 80% RH) at 21 °C, sporulation occurred periodically, only when humidity was high. There was no evidence of an endogenous rhythm in continuous light or dark.

ISSN:0008-4026    

DOI:10.1139/b73-070

出版商:NRC Research Press    

年代:1973

数据来源: NRC