摘要:

The rate coefficients of the exponential period of growth of the vegetative organs of Marquis wheat were changed and made biphasic by the morphogenesis of the stem apex from the vegetative to the flowering state. The rate coefficient of stem elongation was lower in the initial or vegetative phase than later, and it was initially insensitive to temperature up to 20 °C but temperature sensitive in the final or flowering phase from 10 °C to 30 °C. In contrast the growth coefficients of plant, shoots, and roots computed from measurements of dry weight were higher in the first phase than in the second phase and increased with temperature to a maximum at 20 °C in both phases. The differences were attributed to the less autotrophic nature and initially more limited growth of the stem. The raised stem-growth coefficient in the flowering phase was compensated by slowed growth of its shoot. Tillers grew most rapidly, successive tillers more so, and accounted for the previously observed dominant growth of "stems" as stems plus leaf sheaths. The change of slope within the exponential plots was not noticed in previous work at 25 °C and it portends higher maximal coefficients for vegetative (initial phase) plant growth than those previously estimated from the entire exponential period. However, under optimal conditions the growth coefficient of the whole plant seems to be internally limited to about half that of one or another organ.

ISSN:0008-4026    

DOI:10.1139/b73-158

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Stored lipid decreased in cotyledons of afterripening seed of sour cherry (Prunus cerasusL.). The lipid apparently is degraded to acetate and metabolized by the glyoxylate cycle and reversal of glycolysis to free sugars, which are then transported to the embryonic axis, the major site of respiration during afterripening. The provision of substrate allows for activation of the pentose phosphate cycle, an increased respiratory rate of this tissue, and production of the necessary intermediates for synthesis of essential structural elements necessary for the germination process.

ISSN:0008-4026    

DOI:10.1139/b73-159

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

The ascocarp initial ofAscobolus michaudiiBoud. is a coiled, septate ascogonium that is enveloped by hyphae that originate from nearby vegetative cells. The young asci and paraphyses develop within the closed, immature apothecium, and the species is therefore cleistohymenial. Opening of the apothecium occurs during the mid-mesohymenial phase of development. Single ascospore cultures are fertile. The origin of the sheath hyphae inA. michaudiiis compared with other species ofAscobolus.

ISSN:0008-4026    

DOI:10.1139/b73-160

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

The brown coloration of ascospores is rejected as a generic character in the Hypocreales. The asci of the type species ofMacbridella, M. chaetostroma(=Herpotrichia rhodosticta), are bitunicate.Macbridella olivacea(=M. cinnabarina),M. amazonensis, M. sansevierae, andM. striisporahave unitunicate asci and are treated as species ofNectria. The asci of the type species ofLetendraea, L. eurotioides, are bitunicate.Letendraea eurotioidesis lectotypified.Phaeonectriais found to be synonymous withCalostilbe; Calostilbeis regarded as a synonym ofNectria.

ISSN:0008-4026    

DOI:10.1139/b73-161

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

A series of raised-beach systems in northwestern Ontario were examined using principal-component analysis and a number of broad plant associations were delimited. A definite trend exists from the younger raised beaches adjacent to the coastline, to the older ridges examined some 8 km inland. This trend has been characterized by the major species involved and by the plant associations relating to specific ridge groups. The paper also lays the foundation for a series of detailed studies which are currently in progress.

ISSN:0008-4026    

DOI:10.1139/b73-162

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Soil moisture measurements are presented for the summer period of 1971 for nine sites spaced inland from the Hudson Bay coastline adjacent to East Pen Island. The sites show a great variation in natural vegetation from a sparsely vegetated young raised-beach to older beach ridges dominated by thick mats of lichen. The sites include a non-vegetated blowout in a sand dune and areas which have been damaged by caterpillar tractors and by burning.Differences in soil moisture between sites are very pronounced and are closely related to the organic content of the soils. There are also substantial variations in the rate of soil moisture withdrawal during the summer period and this is reflected in differences in the seasonal evapotranspiration rates. The soil moisture characteristics are widely variable in the surface soils at the different sites but virtually the same at soil depths below 30 cm.

ISSN:0008-4026    

DOI:10.1139/b73-163

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Haptoglossa heterosporaDrech. is redescribed and compared withH. zoospora, which is described as new. InH. zoosporathe contents of the infection thallus cleave to form primary zoospores. The encysted zoospore is homologous with the spherical primary spore ofH. heterospora. The secondary glossoid spores are apparently not adhesive as previously claimed. The peculiar shape of glossoid spores is related to a unique mechanism of infection whereby infective tertiary spores are injected into nematodes in an extremely short period of time. Tertiary spores develop into separate thalli.

ISSN:0008-4026    

DOI:10.1139/b73-164

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

The scanning electron microscope is used in an examination of the sporangia of 18 described and 3 undescribed species ofCoelomomyces. As a possible aid to taxonomy, those species considered in this study are grouped into eight morphologically recognizable groups. The complementary use of light microscopy and scanning electron microscopy in studies of this type is emphasized.

ISSN:0008-4026    

DOI:10.1139/b73-165

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

The production of ethylene by xylem tissues ofPinus radiatawas monitored throughout the year. Statistically, significantly greater quantities of ethylene were produced during the winter by transition zones separating sapwood from heartwood than by transition zones during the rest of the year and by middle and inner sapwood during the entire year. Ethylene (5 ppm in air), but not carbon dioxide (27.5% in air), stimulated the production of pinosylvin in sapwood blocks. Phenol synthesis appeared to be preceded by desiccation during both heartwood formation and wound response. Tests with cycloheximide indicated that transition zones are capable of protein synthesis. It was suggested that the auxin-ethylene balance could contribute to quantitative and seasonal differences in ethylene production between the wound and senescent responses (heartwood formation). These and other results suggest that (i) ethylene is involved in stimulation of respiration and phenol synthesis during the wound and senescent responses of xylem tissues of this species, and (ii) heartwood formation takes place mainly in the dormant season during increased metabolic activity in the transition zone.

ISSN:0008-4026    

DOI:10.1139/b73-166

出版商:NRC Research Press    

年代:1973

数据来源: NRC

摘要:

Brycekendrickiagen. nov. andB. indicasp. nov. are described. Revised descriptions ofVasudevellaand its type speciesV. sporoboliare provided.

ISSN:0008-4026    

DOI:10.1139/b73-167

出版商:NRC Research Press    

年代:1973

数据来源: NRC