摘要:

The autotoxic properties ofKochia scopariaphytotoxins on its germination and on radicle and seedling growth were studied. Inhibition of seed germination, a commonly known allelopathic phenomenon, did not occur and seeds reached close to 100% germination within 24 h when tested against different phytotoxins isolated fromKochialeaves regardless of the concentrations applied. Similarly, the radicle length ofKochiaseeds measured was not significantly affected. However, when radicles were allowed to grow for an extended period of time in various concentrations of isolated phytotoxins, their length was significantly reduced in almost all cases. Such autotoxic growth retardation patterns were more pronounced in 10-day-old seedlings. It appears thatKochiaphytotoxins do not inhibit germination but retard growth later, which also supports the high density but drastically reduced growth ofKochiain its 2nd year of revegetation in the field. The autotoxins isolated and identified fromKochialeaves were phenolics and flavanoids.

ISSN:0008-4026    

DOI:10.1139/b79-132

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The effects of gibberellic acid (GA3) on the penultimate leaflets of dwarf and normal cultivars of pea were investigated. In control plants, the leaflets of the dwarf were heavier, thicker, and had a smaller surface area than the normal. Epidermal and palisade cells of the dwarf were longer than those of the normal cultivar and the dwarf had longer spongy mesophyll cells and more layers of spongy mesophyll than the normal, with fewer intercellular spaces.Application of GA3to dwarf plants increased leaflet surface area and length of epidermal cells, while leaflet weight and thickness and the number of layers of spongy mesophyll cells decreased. No significant changes in the leaflet of the normal cultivar were induced by GA3.The overall effect of GA3application to the dwarf cultivar was to induce a degree of differentiation in the penultimate leaflets such that they tended to resemble more closely those of the normal cultivar.

ISSN:0008-4026    

DOI:10.1139/b79-133

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Polygonum-type embryo sac development was examined inZea mayswith light, fluorescence, and electron microscopy. Megasporocyte polarity is expressed in organelle distribution, aniline blue wall fluorescence, and chalazal location of plasmodesmata. In the meiotic cytoplasm concurrent with the sporophyte–gametophyte transition, ribosome concentrations are low, and membrane-bound organelles are simplified. The functional megaspore is the largest and most chalazal cell of the resultant triad or tetrad. Aniline blue fluorescence is intense in nonfunctional megaspore walls, whereas in the functional megaspore intensity decreases from the chalazal end to that in nucellar walls. Throughout functional megaspore and two-nucleate megagametophyte, ribosome concentrations, organelle numbers, and structural complexity increase. The transition from vegetative to reproductive gametophytic growth presumably follows this biosynthetic period. In the four-nucleate stage, a second phase of mitochondrial simplification coincides with the formation of an extensive lytic vacuole containing evidence of possible organelle and cytoplasmic membrane incorporation. Near the close of intensive lytic activity, compartmentalization of lytic areas contributes to creating a prominent vacuole in the central cell as synergids, egg, and antipodals differentiate.

ISSN:0008-4026    

DOI:10.1139/b79-134

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The vegetation of the Enchantment Lakes Basin, which is located at and above timberline on the slopes of Mount Stuart, Washington, was examined by classification and ordination methods. A vegetation map relates the 21 recognized community types to physiographic and topographic features. Vegetation was divided into plots with and without trees. The 11 forested communities include those dominated byLarix lyalliiandCassiope mertensianaon moist slopes,L. lyalliiandPhyllodoce glandulifloraon steep north-facing slopes,Abies lasiocarpaandVaccinium inyrtilluson low elevation, moist sites, and several communities dominated byPinus albicaulison dry, exposed slopes. The 10 alpine communities include dry fell-fields dominated byLupinus lepiduswith a variety of forbs, communities dominated byCassiope mertensianaandPhyllodoce glandulifloraand byP. empetriformis, and lush and wet meadow communities dominated byLupinus polyphyllusandCarex nigricans. These communities are related to those identified by other workers in the Pacific Northwest. Keys to the vegetation of this area are presented. Indirect gradient analysis using reciprocal averaging revealed both vegetation and species patterns. In the subalpine, moisture appears to be the dominant operational gradient, while inferred temperature is a secondary factor. In the alpine vegetation, a combined gradient of moisture and exposure is indicated by reciprocal averaging. Special ordinations derived from reciprocal averaging reflect these interpretations and identify indicator species for particular habitats in both subalpine and alpine. The patterns are summarized with a mosaic diagram. The use of multivariate methods provided means to summarize primary survey data quickly and efficiently. The pattterns thus revealed are comparable to other studies in the Pacific Northwest and thus engender confidence in the use of indirect gradient analysis as a valuable tool for primary survey in these ecosystems. A vegetation map, keys to vegetation types, community and species patterns, and the relationship between classifications and ordinations emerged from this study.

ISSN:0008-4026    

DOI:10.1139/b79-135

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Flammulina velutipesfruit bodies only grew normally if the pileus remained on the stipe until the end of rapid elongation when about 80% of the final length had been reached. During the same period lamellae alone increased stipe growth significantly compared with total decapitation. The stipes attained three-quarters of the length of intact fruit bodies with only about one-third of all lamellae. Near the end of the normal growth period, the stipe became independent of the pileus and lamellae. Small amounts of lamellae excised during rapid elongation produced diffusate in dilute potato glucose agar which promoted growth of decapitated stipes of the same age. The activity could be detected when fruit bodies had completed two-thirds of their normal growth but was much less than at the onset of rapid elongation. Tests of diffusates from young and old lamellae on stipes of different ages showed that the declining influence of lamellae in aging fruit bodies is associated both with decreasing production of the growth-promoting factor and decreasing response of stipes to an external supply of active diffusate. Neither pilear context nor any part of young or old stipes released growth-promoting diffusate.

ISSN:0008-4026    

DOI:10.1139/b79-136

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Thirteen species of Hepaticae and 184 moss taxa are reported from Banks Island, Northwest Territories, Canada. Of these, 10 Hepaticae and 58 mosses are previously unreported from Banks Island. The list includes literature reports and recent collections.

ISSN:0008-4026    

DOI:10.1139/b79-137

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The planktonic diatomEunotia zasuminensis(Cab.) Körner is reported from eight locations in Ontario, Canada. It is previously known from only four other localities in Europe and Africa and from two rivers in the U.S.A. The taxonomy ofE. zasuminensisis discussed relative to similar species. Observations on the rudimentary raphe in this species emphasize its proper taxonomic position within the Eunotiales. The distribution ofE. zasuminensisseems to be controlled by its apparent preference for slightly acidic or dystrophic waters.

ISSN:0008-4026    

DOI:10.1139/b79-138

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Nitrate reduction did not occur in leaves in the dark in aerobic conditions but did occur in anaerobic conditions. Nitrate reduction in leaves in the dark in aerobic conditions was observed, however, when the respiratory electron transport chain was inhibited with antimycin A but not when it was inhibited with amytal or rotenone. It would appear that NADH generated outside the mitochondria was used for nitrate reduction in the dark under anaerobic conditions. The relevance of this observation to nitrate reduction in the light is discussed.

ISSN:0008-4026    

DOI:10.1139/b79-139

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

With a fixed genome and in uniform culture conditions, the wild-type strain ofNectria haematococcaproceeds from a juvenile state to either of two morphologically distinct differentiated states. These differentiated states appear suddenly as small brown areas in the margin of the thalli and widen to hyphae in the vicinity through transmission of two extrachromosomal factors, each of them being specific for one of the two differentiated states.Mutagenesis indicates that nuclear genes are involved in controlling the establishment of differentiation. Mutations were obtained in at least six genetically independent loci. Some genes influence the maintenance of both differentiated states; others affect them specifically. Studies on the double mutants obtained from crosses between mutant strains reveal information on the mode of action of the genes. The relationships between these genes and the extrachromosomal factors are discussed.

ISSN:0008-4026    

DOI:10.1139/b79-140

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Four new coprophilous species ofSporormiellaare described and illustrated:S. macropulchellafrom Canada, Kenya, Tanzania, and U.S.A.;S. obliquafrom Canada, Kenya, Tanzania, Uganda, and U.S.A.;S. similisfrom Canada, Kenya, Tanzania, and U.S.A.; andS. tenuisporafrom Kenya, Tanzania, and U.S.A. Many additional records are reported for 18 previously described species, several of which are redescribed from axenic cultures. New records are provided for two of the known species ofSporormia.

ISSN:0008-4026    

DOI:10.1139/b79-141

出版商:NRC Research Press    

年代:1979

数据来源: NRC