摘要:

A synoptic key toEupenicilliumand sclerotigenicPenicilliumspecies is presented. Based on cultural characters and the imperfect state, it enables identifications to be made after 7 days incubation, avoiding the necessity of awaiting maturation of the perfect state.

ISSN:0008-4026    

DOI:10.1139/b74-290

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

A technique to perform intraspecific crosses inUstilago nuda(Jens.) Rostr. was developed and applied to study the inheritance of buff spore color and the inheritance of virulence on the cultivar Warrior. The buff spore color of an albino strain was recessive to the brown color of the wild type. Virulence on Warrior was also recessive. This virulence and that on the cultivar Titan has been transferred from a wild-type strain into the buff strain.

ISSN:0008-4026    

DOI:10.1139/b74-291

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The latest comprehensive classification ofAvenaspecies was established by Malzew in 1929. It has been used by oat workers until today, in spite of the fact that for decades it became gradually outdated partly because new data became available and partly because new species were discovered. This necessitated a new attempt to classify the oats. The present study uses new characters and various numerical taxonomic techniques such as Gower's coefficient of resemblance and eight sequential, agglomerative, hierarchical clustering strategies. Thus 80 different classifications were formed, of which 21 were chosen as admissible. The best classification among the 21 is that which contains maximum information in the information-theoretic sense, i.e., using Eastabrook's model for character analysis. The relationships between the various classifications and the best one are extrapolated through principal coordinate analysis using the information-theoretic correlations between pairs of classifications as measure of distance.As a result, seven groupings were recognized, and canonical analyses were performed on these. Subsequently the canonical loadings were used here as unorthodox diagnoses for the seven groupings, which were then designated as taxa at the sectional category. A formal treatment of these newly established sections is provided in compliance with the rules of nomenclature.Finally, interrelationships between species are also studied using overlapping clusters based on the method of maximal complete subgraphs of Jardine and Sibson.

ISSN:0008-4026    

DOI:10.1139/b74-292

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Cytological studies onThielaviopsis basicolarevealed that other than a low frequency of multinucleate endoconidia in some isolates the uninucleate condition prevailed. Of the six isolates that were studied, three possessed some multinucleate spores. The nuclei in a multinucleate endoconidium were all derived by successive mitotic divisions of the single generative nucleus in the conidiophore. The nuclei in the multinucleate endoconidium divided independently and segregated into uninucleate and (or) multinucleate components during the course of endoconidial germination and subsequent hyphal development. The implications of the results are discussed with regard to the occurrence of cultural variability in this fungus.

ISSN:0008-4026    

DOI:10.1139/b74-293

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Seedlings of flax (Linum usitatissimumL.) were grown in sand culture under controlled conditions and the bud at node 3 was released from apical dominance by increasing the concentration of N in the nutrient solution. Within 24 h of increasing the N supply the number of mitoses per bud had markedly increased and within 48 h the length of the bud was significantly greater than the controls. A distinctive group of cells (the "quiescent center"), characterized by enlarged nuclei with a reduced Feulgen staining reaction, was present at the apex of all inhibited low-N buds but rapidly disappeared when the buds were released from inhibition. Of the buds examined 48 h after the N supply was increased, about 50% had no xylem in the bud trace; the rest had only a single xylem strand and none had established a connection with the stele of the parent stem. Buds examined after 72 h showed a marked increase in the number of xylem strands, but more than 75% of these buds still lacked a complete xylem connection with the vascular tissue of the parent shoot.These results support the hypothesis that the release of lateral buds from apical dominance is not dependent on the prior strengthening of the xylem connections and that associated changes in vascular tissue development are the consequence rather than the cause of the release of the bud from inhibition.

ISSN:0008-4026    

DOI:10.1139/b74-294

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

A mass of colleters occurs at the base of each of the large paired stipules, which form a sealed cone around the bud. Each colleter is a finger-like protuberance about 1 mm in height, with a relatively massive axis of elongate cells surrounded by epidermal cells elongated perpendicular to the axis. No special association of vascular bundles with colleters was observed, nor were any transfer cells seen.Rhizophoracolleters are remarkably similar to those found in several other families.

ISSN:0008-4026    

DOI:10.1139/b74-295

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Two unidentified, imperfect fungi were isolated from 3-year-old nursery seedlings of red pine. One, referred to as BDG-58, appears to be very similar to the E-strain fungus isolated by Mikola in Finland. It is light brown in culture with septate, smooth to verrucose hyphae, 4.4–8.8 microns (μ) in diameter. It produces large spherical chlamydospores, 45–100 μ in diameter, in a peat moss – vermiculite – nutrient medium substrate used in mycorrhizal synthesis experiments with red pine. Chlamydospores are terminal on chains of 3–15 supporting cells. Associated with the roots, chlamydospores are more variable in form, being terminal and solitary, occasionally sessile, or intercalary. The intercalary may be either solitary or in chains. This fungus forms ectendomycorrhizae which possess a coarse Hartig net and coarse, heavily branched intracellular hyphae.The second fungus, referred to as BDD-22, is black in culture with smooth or minutely echinulate hyphae mostly 3 μ in diameter and torulous (or moniliform) hyphae 6.6 μ in diameter. Conidiophores and conidia are abundant in modified Hagem's liquid medium at 6 months. Conidiophores are semimacronematous, solitary or branched, 20–70 μ long, greenish-black and smooth. Conidiogenous cells are phialidic and collarettes are readily discernible. Chlamydospore-like cells are common, solitary or in chains. The fungus, tentatively identified as aChloridium, forms ectendomycorrhizae which possess fine intercellular hyphae and masses of spherical intracellular bodies which are spore-like in appearance.

ISSN:0008-4026    

DOI:10.1139/b74-296

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

A comparative study of the ontogeny of sporangia and paraphyses showed that these organs are homologous, with divergence in structure and function occurring after several divisions in the initials of these organs. Paraphyses develop an elongated stalk bearing several vesiculated cells, most of which bear appendages or glandular hairs. Sporangial initials form stalks that subtend the sporangium or spore case enclosing cells which undergo meiosis to form spores. The stalk and vesiculated cells of each paraphysis have a rather complex cytoplasm in the early stages of ontogeny, but ultimately these cells become vacuolated with large deposits of tannins. The tannin bodies originate in small cytoplasmic vacuoles which appear to fuse, forming larger vacuoles with tannin deposits. Stalk and annulus cells of the sporangia also form vacuoles with tannin inclusions. The appendages of the vesiculated cells remain cytoplasmic much longer than the subtending vesiculated cells, but eventually they vacuolate and form tannins as well. It is suggested that the paraphyses perform a protective function for the developing sorus to prevent the loss of water from the developing sporangia.

ISSN:0008-4026    

DOI:10.1139/b74-297

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Blue grama [Bouteloua gracilis(H.B.K.) Lag. ex Steud.] plants from a native shortgrass prairie were subjected to four treatments at three different temperatures in a growth chamber experiment to evaluate the dynamics of labile and nonlabile energy components in different plant organs. At high temperature regimes (24°/13° and 29.5°/18 °C day–night) blue grama plants accumulated comparatively greater amounts of labile and nonlabile energy in the three organs, viz., shoots, crowns, and roots, than at low temperature regime (13°/7 °C). The labile energy in shoots at the three temperature regimes continued to increase up to a peak value recorded at 90 days and then declined during the subsequent 30-day growth period. On the other hand, the accumulation of labile energy in roots and crowns continued till final harvest. Irrigated plus N-fertilized plants accumulated more labile and nonlabile energy in their shoots than did the irrigated plants, and the latter accumulated more than the fertilized and the control plants. The labile and nonlabile energy components in fertilized plants were at lower levels than the control plants during the 120-day growing period, resulting in net negative energy balance as compared with control plants. Higher temperature, irrigation, and irrigation plus nitrogen application decreased the nonlabile:labile ratios in the plants.

ISSN:0008-4026    

DOI:10.1139/b74-298

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The proportion of the total aerial dry weight ofEquisetum sylvaticumdevoted to spore producing and supporting structures does not change in the first 6 years of postfire succession: the ecological strategy remains constant. However, the stem and branch lengths of sterile shoots, their time of appearance, and the distribution of dry weight between sterile shoots do vary during the same period, indicating changes in ecological tactics. The tactical changes appear to be a response to increasing competition. Clones ofE. sylvaticumsurvive repeated fires by means of the deeply buried rhizomes and are evidently very long-lived.

ISSN:0008-4026    

DOI:10.1139/b74-299

出版商:NRC Research Press    

年代:1974

数据来源: NRC