摘要:

The changes in total lipid, fatty acid, and lipid phosphorus contents were followed during germination and early growth of Rideau wheat seedlings at 24° for 72 h and 2° for 5 weeks. At both temperatures the changes in total lipids and total fatty acids were similar for seedlings at comparable stages of morphological development. In contrast, the phospholipid content of seedlings grown at 2° was considerably higher than that of seedlings grown at 24°. A marked increase in linolenic acid was also observed during growth at 2°, and this change occurred entirely in the embryo. The results indicate an increased synthesis and unsaturation of membranes in seedlings grown at 2°. The changes may contribute to the increased resistance to freezing temperatures exhibited by seedlings grown at 2°.

ISSN:0008-4026    

DOI:10.1139/b72-308

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Atriplex confertifoliaandEurotia lanataplants were studied in the field and laboratory under controlled conditions of temperature and vapor pressure deficit with uniform wind speed and light intensity and various levels of water stress. Multiple regression analysis indicated that under both field and laboratory conditions, vapor pressure deficit and water stress were significant factors influencing transpiration. Phenological stage was also a major factor in the transpirational relationships of both species in the field. Transpiration rates under comparable conditions tended to be higher forEurotiathan forAtriplexon a leaf dry weight basis with less pronounced differences on a leaf area basis. However, in the latter part of the summer, transpiration rates ofEurotiadecreased markedly whileAtriplextended to maintain active transpiration. Under laboratory conditions both species exhibited transpiration at plant moisture stress values as great as 115 bars.

ISSN:0008-4026    

DOI:10.1139/b72-309

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Conidium ontogeny in theMoniliastate ofNeurospora sitophilaandSclerotinia laxais analyzed by time-lapse photomicrography, and nuclear configurations occurring during conidiogenesis in the former are described.

ISSN:0008-4026    

DOI:10.1139/b72-310

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

A cytological investigation of four biotypes ofThielaviopsis basicolaisolated from field soil and of three cultural variants revealed that the hyphal cells, conidiophores, endoconidia, and chlamydospores are regularly uninucleate except those cells in which nuclear division or nuclear migration has occurred.The nucleus in the end cell of the conidiophore divides mitotically and successively after cell division to produce a chain of uninucleate endoconidia. During the formation of chlamydospores, a daughter nucleus migrates from the mycelial cell into the chlamydospore primordium. This primordium later forms a one-celled chlamydospore. If the chlamydospore consists of more than one cell, all the nuclei in the cells are derivatives of the nucleus in the primordium.Nuclear migration from one cell to another was observed to take place by means of anastomosis and (or) through septal pores of the mycelia. Anastomosis occurs between mycelia, between endoconidia, and between a mycelium and an endoconidium.The entire process of mitotic division occurs within an intact nuclear envelope. An intranucleate spindle was demonstrated in dividing nuclei in living preparations. Stained preparations revealed that there are four chromosomes inT. basicola.

ISSN:0008-4026    

DOI:10.1139/b72-311

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

In 1967 yellow birch,Betula alleghaniensisBritt., and white birch,B. papyriferaMarsh., developed extremely large seed crops in Ontario. Foliage was dwarfed or missing in the heavily seeded portions of tree crowns. Buds did not develop on the terminal portions of most branches, and in 1968 branches died back to the point where buds were available for growth. Terminal growth and diameter growth were reduced for both species in 1967, and terminal growth by yellow birch continued at a reduced rate in 1968. Terminal growth and bud production were inversely related to the amount of fruiting. Similar conditions prevailed on some yellow birch in 1970.Yellow birch was more seriously affected, and in most mature stands dieback averaged 20 to 50 cm. White birch was not affected to this extent; however, some trees in most mature stands suffered extensive dieback.

ISSN:0008-4026    

DOI:10.1139/b72-312

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Microscopic observations of oogonia and amphigynous antheridia ofPhytophthora capsiciat several stages of development indicated that the antheridial initial encircled the oogonial initial. Observations of the antheridium in different phases of encirclement, both polar and lateral views, indicate that the oogonial initial does not penetrate the antheridial initial as classically described.

ISSN:0008-4026    

DOI:10.1139/b72-313

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Morphological and nutritional aspects of perithecial formation ofNectria haematococcaBerk. & Br. andHypomyces solaniRke. & Berth, were compared on a variety of media. Maximum perithecial development was observed on "natural" media. In synthetic liquid media, monosaccharides were more suitable for perithecial formation than were other carbon compounds examined. Likewise, amino acids as the sole source of nitrogen were found to be superior to either ammonium or nitrate nitrogen for perithecial production. Further, it was observed that, although light may be stimulatory, it was not an absolute requirement for perithecial induction. Isolates of these species showed remarkable uniformity in the morphology of perithecia, asci, and ascospores. Similarly, the identical response to carbon and nitrogen nutritional requirements for perithecial development substantiates a single identity for the isolates studied.

ISSN:0008-4026    

DOI:10.1139/b72-314

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Exo- and endo-polygalacturonase, polygalacturonatetrans-eliminase, and cellulase were produced in cultures by two virulent, one moderately virulent, and one avirulent isolates ofSclerotium bataticola. The polygalacturonases are important in penetration and early stages of pathogenesis in sunflowers; virulence of isolates is correlated with their ability to produce these enzymes in the host. Polygalacturonatetrans-eliminase and cellulase activity in plant extracts increased with time after inoculation. Polygalacturonatetrans-eliminase and cellulase are not important in penetration ofSclerotium bataticolainto sunflowers, but are involved in further development of the pathogen. Ability to produce these two enzymes in plants is closely correlated with virulence of the respective isolates.

ISSN:0008-4026    

DOI:10.1139/b72-315

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

Starting from simple morphological considerations and a hypothesis involving 'unset' and 'set' wall, a mathematical model simulating the growth of the hyphal tip is derived, and the results displayed by plotter.

ISSN:0008-4026    

DOI:10.1139/b72-316

出版商:NRC Research Press    

年代:1972

数据来源: NRC

摘要:

The septal apparatus ofPolyporus bienniscomprises a swollen dolipore, a pair of occluding plugs, and perforate parenthesomes differentiated from the wall endoplasmic reticulum. The pore occlusions have an opaque terminal portion and a translucent stem inserted in the pore. The domain between the parenthesome and the dolipore is traversed by microfilaments which may serve to bind the septal apparatus together. Matrix material is present between the parenthesome membranes, producing a lamellar appearance. This unique septum is typical for most basidiomycetes.

ISSN:0008-4026    

DOI:10.1139/b72-317

出版商:NRC Research Press    

年代:1972

数据来源: NRC