摘要:

Coastal wetlands of the Hudson Bay Lowlands along southern James Bay are generated by a positive water balance, low relief, and a rising land surface. Marshes, dominated by sedges and grasses, and separated by beach ridges, occur between unvegetated intertidal flats and the inland boreal forest. Bay waters, affected by currents, shallow depths, and large freshwater inputs from major rivers in the Hudson Bay drainage, are brackish. Off the coast at the Harricanaw River, surface salinity in the bay is <4 ppt while soil water salinities in the adjacent marsh are higher. Standing water and tidal water in contact with vegetation often measure 0 ppt salinity. Plant communities adapted to brackish water have developed. Using two-way indicator species analysis classification, twelve widespread community types were recognized. Ordination using detrended correspondence analysis revealed gradients of salinity, elevation, drainage, vegetation development, complexity, and peat formation, and separated coastal from estuarine communities. An inverse salinity gradient, which has been reported elsewhere in James Bay, was not found; explanations are proposed for isolated areas of high salinity.

ISSN:0008-4026    

DOI:10.1139/b86-031

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

Carex subimpressa, originally described as a hybrid ofC.hyalinolepsisandC.lanuginosa, has been reported over a wide area and beyond the range ofC.hyalinolepis. Consequently it has been accorded specific rank. Various aspects of morphology reflected in scatter diagrams as well as intermediate stomatal structure revealed through scanning electron microscopy and sectioning support the hybrid origin as originally proposed. This is further supported by field studies of natural populations where both putative parents were invariably present. Reports from beyond the range of one or both parents are the result of misidentification. The diagnostic character combination includes sparsely pubescent perigynia 4.2–6.4 mm long, with relatively short beaks, leaves 4.5–11 mm wide, and ligules 1.8–9 mm long.

ISSN:0008-4026    

DOI:10.1139/b86-032

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

Growth is the major parameter used to assess novel phenotypes derived from plant tissue cultures. Any quantitative analysis of growth must have an explicit rational basis. Frequently this criterion is not met. For example, the calculation (W2 − W1)/W1(W1 = initial weight;W2 = final weight) approximates neither linear nor exponential growth. Yet, it is a common method of analysis, as is the related calculationW2/W1. When absolute growth values provide insufficient information, meaningful relative growth rate equations can be utilized. Relative growth rates should be evaluated as ln (W2/W1)/(t2 − t1) fort = time, thereby yielding a constant growth rate for exponentially growing cell lines. Linear growth (root growth, for example) can be approximated by 2(W2 − W1)/((W1 + W2)(t2 − t1)). All methods of analysis we have encountered assume that relative growth at a given instant depends on total mass. The possibility exists that growth may actually be proportional to mass raised to some power less than one. For example, growth could be limited to a thin outer shell of a spherical callus. Then the relative growth rate would equal 3(W21/3 − W11/3)/(t2 − t1). Data can be seriously distorted when inappropriate calculations are used. Such distortions are exacerbated when comparisons are made. In all cases an adequate assessment of growth kinetics for each cell line and each treatment is essential.

ISSN:0008-4026    

DOI:10.1139/b86-033

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

Numerous factors must be considered when analyzing growth in a cultured cell system. One extremely critical factor is the initial cell mass. The effect of initial mass (10 to 400 mg) on growth rate was assessed for cell lines tolerant and susceptible to the herbicides 3-amino-1,2,4-triazole (amitrole) andN-(phosphonomethyl)glycine (glyphosate). For a given cell line, the relationship between initial mass and growth rate was comparable in the presence and absence of the growth inhibitors. However, among cell lines the response varied. For one amitrole- and glyphosate-tolerant cell line, increased initial callus mass resulted in an increased relative rate of growth. However, the opposite effect was observed for another cell line which was also tolerant to both herbicides. For a third cell line which was herbicide sensitive no initial mass effect was observed. A fourth cell line (amitrole tolerant – glyphosate sensitive) also showed no initial mass effect except for the very small 10-mg calluses, which had significantly lower growth rates. The observed effect of initial mass was dependent on the method of calculating growth rates.

ISSN:0008-4026    

DOI:10.1139/b86-034

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

OnCichorium intybusroot explants of different size, it is possible to demonstrate the existence of a relation between the volume/surface ratio and adventitious root formation capacities. With a volume/surface ratio equal to one, the highest number of adventitious roots and percentage of explants able to produce roots have been observed. When this ratio deviates from unity, adventitious root formation declines. Cold storage of chicory roots causes breakdown of fructosans and accumulation of sucrose, glucose, and fructose. At the same time, adventitious root formation on explants culturedin vitrodecreases. Inclusion of glucose in culture media increases adventitious root production whatever the duration of chicory root cold storage may have been. Results are discussed and the hypothesis of a regulation of adventitious roots by sucrose and reducing sugars is advanced.

ISSN:0008-4026    

DOI:10.1139/b86-035

出版商:NRC Research Press    

年代:1986

数据来源: NRC

摘要:

The composition of the extrafloral nectar fromAilanthus glandulosavaries according to the type of nectary. When the buds open, those which are located on the cataphylls or the stipules are only supplied by carbohydrate reserves. In this case, a high sucrose content is found in the nectar, and rhamnose is also detected. The floriferous or sterile state of the trees does not modify the sugar composition of the foliar nectar. For amino acids, the predominance of serine, threonine, and proline is constant in all types of nectars. The amount of proline is very important in the nectar of the cataphylls and increases with the age of the leaf. The activity of the foliar nectaries seems to correlate with the occurrence of a requirement for photosynthetic products. The nectaries from trees developing fruits or from those showing only vegetative growth continue to be functional for a long time. The ablation of foliar nectaries leads to a sugar accumulation in the leaf and slows down the reconstitution of starch reserves in the branch. The function of the extrafloral nectaries is interpreted as being the elimination of excess sugars. Thus, the initiation of these nectaries may be due to a carbohydrate accumulation during the ontogeny of foliar organs.

ISSN:0008-4026    

DOI:10.1139/b86-036

出版商:NRC Research Press    

年代:1986

数据来源: NRC