摘要:

Riessa semiophorais an imperfect fungus with basidiomycetous affinities. In culture, the fungus produces two types of conidia: unicellular microconidia and the compound stauroconidia that typify the genus. Both types of conidia are dikaryotic and on germination give rise to a mycelium bearing clamp connections. Their ontogeny is holoblastic, the microconidia arising as separate blown-out points on the apex of the conidiophore, while the stauroconidia develop by the enlargement of the conidiophore apex into, usually, four lobes. Each cell of the stauroconidium is binucleate and capable of germination.

ISSN:0008-4026    

DOI:10.1139/b73-183

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Changes in species composition and plant cover were studied in relation to moisture regime over a 10-year period in 71 shallow marsh wetlands in the grassland and parkland regions of Saskatchewan. Decreases in density of the shallow marsh emergentsPolygonum coccineum, Carex atherodes, Scolochloa festucacea, andEleocliaris palustrisoccurred with greater-than-normal water depth at the start of the growing season but 2 or more years of continuous flooding were required to eliminate emergent cover completely and convert the wetland to open water. Repeated autumn reflooding also resulted in complete elimination of emergent species. Changes in species composition occurred when basins were grazed and as vegetation reestablished after cultivation but no changes followed mowing or burning.Alopecurus aequalis, Beckmannia syzigachne, Glyceria grandis, andG. pulchellaare designated as "disturbance" species on the basis of their response to soil-exposing events. Presence of small amounts of deep marsh emergents in shallow marsh wetlands is not considered a reliable indicator of wetter moisture regime. Species composition of rooted submergents in a wetland can be used as an indicator of its moisture regime. Shallow marsh wetlands in basins of 1 ac (0.41 ha) or less experienced little year-long flooding and converted to open water only under atypical conditions. Larger wetlands required basin depths in excess of 36 in. (96.4 cm) to have any amount of year-long flooding and to convert to open water. These basin size and depth criteria have applications in habitat evaluation by waterfowl managers.

ISSN:0008-4026    

DOI:10.1139/b73-184

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Field observations were made on wound and pathological periderms, regardless of the causal agent, and periderms formed at abscission zones, old resin blisters and rhytidomes inAbies amabilis(Dougl.) Forbes,Abies grandis(Dougl.) Lindl.,Tsuga heterophylla(Raf.) Sarg., andThuja plicataDonn. It was established that these periderms were of reddish-purple sequent periderm (rsp) type, rather than either the brown first periderm (bfp), or brown sequent periderm (bsp) types. These reddish-purple pigmented periderms, like thersp(the usual sequent periderm) were found abutting necrotic tissues and were moreover identical withrspin 15 newly demonstrated cryofixation and chemical characteristics. Because of this equivalence, it is proposed that all these reddish-purple periderms, including the usual sequent periderm (rsp), constitute one category, the necrophylactic periderms. These periderms arise whenever regeneration of a periderm after death of cells is required, and their main function seems to be protection of living tissues from the adverse effects associated with cell death. Because of the equivalence ofbfpandbsp, they constitute another category, the exophylactic periderms. This second category of periderms has a common function of protecting living tissues against the external environment.

ISSN:0008-4026    

DOI:10.1139/b73-185

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Theoretical and experimental aspects of the equilibrium water relations of excised hemlock (Tsuga canadensis) shoots are examined. The equilibrium water relations of hemlock were determined by using the pressure-bomb technique on shoots 15 to 40 g in fresh weight. At or near full turgor the osmotic pressure of the cells averages 16.5 + 0.4 bars. The fraction of the total water content of hemlock shoots residing in the living cells is 0.77 + 0.04. When hemlock shoots are near full turgor the balancing pressure will change linearly with the volume expressed provided the volume changes represent less thanof the total shoot water content.

ISSN:0008-4026    

DOI:10.1139/b73-186

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

We present a theoretical analysis of the events that occur while a plant enclosed in a pressure bomb evolves from one equilibrium balancing pressure to another. The initial rate of efflux from any one cell in response to a pressure increment of ΔPequals (ALp)iΔP, where (ALp)iis the surface area times hydraulic conductivity of the cell's semipermeable membrane(s). If the volume changes and pressure increment are small, the cell will approach equilibrium exponentially. The half time of the exponential process is governed by (ALp)iki, wherekiis the cell constant (= the combined rate of change of osmotic and turgor pressure with the volume expressed from the cell). Experimental studies of the kinetics of water exchange between the symplast and apoplast of hemock (Tsuga canadensis) shoots in a pressure bomb reveal that the cells collectively behave as though they fall into three distinct populations which approach equilibrium with different half times.

ISSN:0008-4026    

DOI:10.1139/b73-187

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

An extension of the description ofAzolla schopfiiDijkstra to encompass the vegetative parts was made possible by the discovery of vegetative material ofAzollawith attached reproductive structures at the Genesee fossil plant locality of Paleocene age in central Alberta.Detailed descriptions of the reproductive structures ofA. schopfiiare given. A close relationship is suggested betweenA. schopfiiand species within subgenusRhizospormaMeyen, particularlyA. niloticaDecainse, based on similarities in the morphology of the vegetative parts and their associated reproductive structures.

ISSN:0008-4026    

DOI:10.1139/b73-188

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

A new eight-spored species,Trichobolus octosporus, is described and illustrated. The generic concept has been enlarged to include this taxon. A revised generic description and key are provided. The species is discussed in relation to previously known organisms within the genus.

ISSN:0008-4026    

DOI:10.1139/b73-189

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

The fluorescent staining properties of aniline blue and primuline with isolated preparations of variously linked glucans was investigated. Neither fluorochrome was specific for β (1→3) linked glucose units.

ISSN:0008-4026    

DOI:10.1139/b73-190

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Soybean plants (Glycine max'Harasoy') were cultured in a controlled environment room and studied at seven ages ranging from 16 to 40 days after flowering. Fruits from each age group were labeled by translocation of organic compounds from leaves which had photosynthetically incorporated14CO2. Leaf blades, petioles, and seeds were extracted in boiling ethanol at the termination of labeling experiments. Seeds were also harvested and extracted 1, 2, and 8 days after labeling. Distribution of label in leaf blades and petioles was essentially the same in all age groups with more than 90% of the activity in petioles being found in carbohydrates. Little or no translocation of amino acids and organic acids was occurring. In seeds, most of the label appeared in the carbohydrate fraction immediately after labeling; however, at 2 and 8 days after labeling the label seemed to be transferred to lipids and the ethanol-insoluble residue. The rate of transfer decreased as a function of seed age. Levels of activity in the amino acid and organic acid fractions were low in all samples.

ISSN:0008-4026    

DOI:10.1139/b73-191

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Cell-wall-free endosperm cells of the African blood lily (Haemanthus katherinaeBaker) were observed while undergoing mitosis on control medium or on medium containing the herbicide trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine). The percentage of cells proceeding from an initially observed stage to the next stage, in controls versus treatments, was as follows: prophase to prometaphase, 85 versus 16; prometaphase to metaphase, 80 versus 33; metaphase to anaphase, 95 versus 50; and anaphase to cell plate appearance, 98 to 49%.An analysis of time-lapse films of trifluralin-treated mitotic cells reveals that many of the previously reported abnormalities do not represent end points of herbicide action, but rather stages leading to fusion of daughter nuclei. Ultrastructural studies show a decreased number of microtubules and an accumulation of large vesicles in the cell plate region. These vesicles exclude microtubules and cell plate material. It is postulated that the decrease in number of microtubules and in the amount of cell plate material permits movement of daughter nuclei to a central position where fusion occurs.

ISSN:0008-4026    

DOI:10.1139/b73-192

出版商:NRC Research Press    

年代:1973

数据来源: NRC