摘要:

Three artificial populations, with leaf area indices (L) of 4.4, 1.5, and 0.54 were submerged in identical tubs of 1-m3capacity. Experiments showed that the maximum vertical temperature gradient of the water varied and was dependent on the ratio of solar radiation to wind speed, the leaf area index, and the arrangement of the leaves in the population. The time of day of the maximum temperature gradient was also dependent onLand leaf arrangement. The interception of the light energy by the leaf surface heated the water locally, while the shadow beneath caused the temperature to remain low. With fewer plants, water evaporation was slightly greater. Evaporation resulted in a marl deposit which was confined to the upper surface of the leaves.

ISSN:0008-4026    

DOI:10.1139/b78-122

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The germination of sclerotia ofMacrophomina phaseolinafrom 3- to 20-day-old PDA cultures incubated at 32 °C and 24 °C varied from 98 to 25% and 75 to 30%, respectively. Germinability of sclerotia from cultures of all ages tested was rapidly lost during storage in desiccators for 24 h at 6 °C or in screw-top vials at room temperature for 30 days. Germination of sclerotia stored in screw-top vials at 6 °C for 30 days declined less rapidly. There was a linear relationship between the size of the sclerotium and the number of germ tubes emerging from it. The role of sclerotium size in survival and what factors may be responsible for loss of germinability with increasing age of source culture are discussed.

ISSN:0008-4026    

DOI:10.1139/b78-123

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Maize pollen stimulated infection of maize byFusarium graminearumSchwabe both inin vivoandin vitro. Significant increases in percentage germination of macroconidia and length of germ tube ofF. graminearumoccurred in the presence of pollen dialysate, while dextrose and sucrose were not as stimulatory. All concentrations of macroconidia used to inoculate greenhouse-grown maize plants were equally effective in producing lesions in the leaf axils in the presence of pollen. Without pollen, only the highest inoculum concentration was effective and then only half as many lesions were produced. In a survey of two fields, over 90% of the maize plants had lesions in their leaf axils similar to those induced in greenhouse-grown plants. Reduction in dry weight of detached maize silks inoculated with three different spore concentrations was greater in the presence of pollen than in its absence.

ISSN:0008-4026    

DOI:10.1139/b78-124

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

The analysis ofPiceacone scales from the Sweetgrass Hills of Montana substantiates the existence ofPicea pungensEngelm. in north-central Montana. These results extend the geographical range ofP. pungensand identify a new native species within the state of Montana.

ISSN:0008-4026    

DOI:10.1139/b78-125

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Poria terrestris(DC. per Fries) Sacc., recently discovered to be mycorrhizal with roots of Douglas-fir (Pseudotsuga menziesii(Mirb.) Franco) and western hemlock (Tsuga helerophylla(Raf.) Sarg.), is separated into five distinct varieties. Separation is based on color of basidiocarps, morphology of rhizomorphs, cultural characteristics, color reactions of tissues to chemotaxonomic reagents, differences between respective Douglas-fir mycorrhizae, and fluorescence of tissue under ultraviolet (UV) (3600 Å (1 Å = 0.1 nm)).Byssoporia, a new genus, is proposed forP. terrestrisand its varieties.

ISSN:0008-4026    

DOI:10.1139/b78-126

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Compatibility analysis was applied to a set of evolutionary units (EUs) whose true cladogram is known. These EUs consisted of 16Avenacultivars. The results show great differences between the true cladogram and the generated trees. Very few characters were found to correctly reflect the cladistic relationships among the 16 EUs. An attempt is made to explain this discrepancy, and as a result, a number of unanswered questions are raised.

ISSN:0008-4026    

DOI:10.1139/b78-127

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Zingiberopsis attenuataHickey and Peterson is a new species of monocotyledon from the Paleocene Paskapoo Formation of Alberta. Leaves of this species with their parallel veins grouped into three size sets are intermediate between the Late CretaceousZingiberopsis magnifolia(Knowlton) Hickey, new combination, with four discrete sets andZingiberopsis isonervosaHickey, of late Paleocene and early Eocene age, with only one set.Zingiberopsishas large, elliptic to ovate leaves with a costa composed of a number of concurrent strands, a set of parallel veins emerging at low angles from the costa, and relatively distantly spaced transverse veins running between adjacent parallel veins. Morphology of the genus matches that ofAlpiniain the Zingiberaceae except for greater irregularity of the parallel vein set at and near their origin on the costa and the lack of any evidence of a ligule on the petiole as inAlpinia. Species ofZingiberopsisdemonstrate a clear trend toward loss of the wider parallel vein subsets over the approximately 20-million-year range of the genus. In addition, the overlooked character of the arrangement of the parallel vein subsets across the width of the leaf may have potential in the taxonomic determination of monocotyledonous leaves.

ISSN:0008-4026    

DOI:10.1139/b78-128

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Hypocotyl segments excised from seedlings ofSantalum album(sandalwood tree) grown in vitro were cultured aseptically on various nutrient media. Regeneration of shoot buds on explants was observed on basal media supplemented with auxins like IAA, IBA, NAA, or NOA. Shoot bud formation was completely suppressed on 2,4-D orpCPA medium. Cytokinins stimulated and enhanced shoot bud formation better than auxins. Excised stem segments from adult plants did not respond to any hormonal treatment. The importance of this method in the propagation of the sandalwood tree is emphasized.

ISSN:0008-4026    

DOI:10.1139/b78-129

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Ordination models of approximate environmental and dynamic relationship between eight boreal tree species were constructed based upon principal components analysis and Kruskal's nonmetric multidimensional scaling. The assumptions inherent in these models are stated and discussed. The data consisted of 152 forest stands from the closed-crown boreal forest zone of Ontario and Quebec south of James Bay. Sequential forest succession, as demonstrated by similar techniques for a section of the Wisconsin evergreen–hardwood forest, is not common in the region of boreal forest studied. However, for those species in common between this and the Wisconsin study, similar dynamic pathways are indicated despite differences in sample size and field technique. Tree species developmental pathways, as indicated by 'succession vectors' on the ordination models are, for the most part, short and circular with the exception ofAbies balsamea(balsam fir). This reflects the reestablishment of similar, relatively monospecific forest stands following catastrophic forest destruction by fire and (or) other agencies. Where catastrophe does not intervene, deciduous primary forest species may be succeeded by an understory ofA. balsameaor byPicea mariana(black spruce). Equally, some forest stands of primary establishment may become decadent with little or no subsequent tree growth. These observations are discussed with respect to the general notion of forest succession.

ISSN:0008-4026    

DOI:10.1139/b78-130

出版商:NRC Research Press    

年代:1978

数据来源: NRC

摘要:

Thirty-three flavonoids have been isolated fromHeuchera cylindricaDougl. var.glabella(T. & G.) Wheelock and at least partially identified. The flavonols kaempferol, quercetin, isorhamnetin, myricetin, and syringetin and the flavone luteolin were found. The flavonols occur in a variety of glycosylated forms, monoglycosides, diglycosides, triglycosides, and gallylated monoglycosides, although not all flavonols exist in all of these forms. Luteolin occurs only as the 7-O-glucoside. Several collections of varietiesglabellaandcylindricaexhibited identical flavonoid patterns as judged by thin-layer chromatography. Flavonoids, thus, cannot be used as varietal markers. Comparison of the flavonoids ofH. cylindricawith those ofH. micranthashows differences which suggest simplification in the flavonoid chemistry associated with evolution within the genus.

ISSN:0008-4026    

DOI:10.1139/b78-131

出版商:NRC Research Press    

年代:1978

数据来源: NRC