摘要:

Twenty-seven of 31 irrigation sources serving the Okanagan and Similkameen valleys of British Columbia were contaminated withPhytophthora. P. cactorum, the cause of collar rot of fruit trees in this region, was recovered from 15 sources;P. cambivoraandP. citricolafrom 1 each;P..megaspermafrom 4 sources. Many isolates of uncertain identity also were recovered.P. cactorum, P. cambivora, andP. citricolawere pathogenic to rootlets of young apple seedlings in laboratory tests, but onlyP. cactorumis considered an important pathogen in this region.

ISSN:0008-4026    

DOI:10.1139/b66-170

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Aeciospores of two caulicolous rusts,Peridermium stalacliformeArth. & Kern (orange- and white-spored) andP. harknessiiJ. P. Moore, belonging to theCronartium coleosporioidesArth. complex, were germinated under different temperature and pH conditions.P. stalactiformegerminated from 10 to 25 °C, andP. harknessiifrom 10 to 30 °C, with optima for both occurring between 15 and 20 °C. Germination was best at pH 6, markedly reduced at pH 5 and 8, and inhibited outside pH 5 to 9 inP. stalactiformeand pH 4 to 9 inP. harknessii. Growth at the optimum temperature and pH for 24 hours resulted in average germ tube lengths of 870 μ and 230 μ forP. stalactiformeandP. harknessii, respectively.P. harknessiiinitiated germination more rapidly thanP. stalactiforme. Germ tubes ofP. stalactiformewere long with multiple irregular short branches. The distal end of the germ tube often produced an appressorium with an infection peg. Germ tubes ofP. harknessiiwere short, with one to three regular short branches and no appressoria. Few differences were found between the two color variants ofP. stalactiforme. A technique for dispersing spores evenly on media is described.

ISSN:0008-4026    

DOI:10.1139/b66-171

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Quantitative data from solution cultures ofAlnus rugosaare presented which indicate facultative independence of this species regarding combined nitrogen supply and its close similarity toA. glutinosain efficiency of N-fixation and physiology of nodule symbiosis.Volume–weight measurements and chemical analyses are given for soils and soil – surface organic matter in stands representative of succession involving nodulatedA. rugosa, confirming that this species is capable of contributing greatly to nitrogen levels of the soil. Total seasonal litter-fall from woody species in several stands was collected and analyzed for nitrogen. Annual amounts of litter-N returning to the ground appear to be substantially greater under alder and alder–forest phases than under those dominated bySalixandSalix–forest vegetation. On favorable sites, soil nitrogen may accumulate underAlnus rugosathickets at rates in excess of 150 lb/acre per year.However, no excess nitrogen accumulation was found in sandy soil supporting theAlnusshrub phase of a dry upland "old-field" succession and an explanation for this has been advanced.The past and present ecological position ofAlnusspecies in northeastern North America is related to their capacity to fix nitrogen.

ISSN:0008-4026    

DOI:10.1139/b66-172

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

The behavior ofArtemisia tridentatassp.tridentataandA. tridentatassp.vaseyanain uniform gardens at Kamloops, Nickel Plate, and Greenstone as well as in some natural habitats supported the separation of the two subspecies. Kamloops (1140 ft) is located in the typical habitat of ssp.tridentataand Nickel Plate (5600 ft) represents the typical habitat of ssp.vaseyana.In their natural habitats ssp.vaseyanaflowered about 2 weeks earlier than ssp.tridentataand their flowering periods did not overlap. In the Kamloops uniform garden ssp.vaseyanacollections showed two distinct flowering patterns considered to be two ecotypes. The ssp.tridentatacollections from the outer edge of the distribution of the subspecies flowered 1 week earlier than collections from the center of the range.Most of the ssp.tridentataplants set out in the Nickel Plate garden died within 3 years but most survived in the one at Greenstone. Almost one-half of the plants of ssp.vaseyanadied in the Kamloops garden, mostly during the summers, except for the Nickel Plate material, which appeared more hardy. About 40% of the United States ssp.tridentatakilled out in the localtridentataenvironment (Kamloops), mostly over winter.Leaves of ssp.vaseyanaplants were typically wider than those of ssp.tridentatabut leaf lengths were variable and not a good diagnostic character. The ssp.vaseyanaplants had a spreading-decumbent growth form while ssp.tridentataplants grew more upright.

ISSN:0008-4026    

DOI:10.1139/b66-173

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Three peroxidase isozymes were isolated from bean leaves by preparative discontinuous electrophoresis on acrylamide gel. The amounts of these isozymes varied with leaf age, suggesting a developmental pattern which might match the metabolic events of maturation and senescence.

ISSN:0008-4026    

DOI:10.1139/b66-174

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Cytology of aeciospores and aeciospore germ tubes of two pine rusts,Peridermium harknessiiJ. P. Moore andP. stalactiformeArth. & Kern, was compared. InP. harknessiithe mycelial cells giving rise to aecia were uninucleate. Young aeciospores were usually binucleate but most of them became uninucleate during maturation. Upon germination, nuclear division and septum formation occurred and germ tubes were divided into two, three, or four cells, each of which usually contained one nucleus. One to three side branches developed and nuclei migrated into them. Basidiospores were not produced. Despite the absence of basidiospores,P. harknessiiis interpreted as having an endo-type life cycle with nuclear fusion and meiosis. InP. stalactiforme, aeciospores were binucleate and, upon germination, two nuclei migrated into the germ tube. The nuclei remained undivided during the formation of appressoria and infection pegs. Septa were not observed and branching was dichotomous or irregular.

ISSN:0008-4026    

DOI:10.1139/b66-175

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Culture filtrates from a virulent and an avirulent strain of each of three phytopathogenic species ofPenicilliumgrown in a defined medium to which were added different sources of organic carbon had endopolygalacturonase (endoPG) and exopolygalacturonase (exoPG), but neither detectable pectin methylesterase nor pectin lyase activity. Extracts from diseased tissue of oranges inoculated withP. italicumorP. digitatumand from diseased tissue of apples inoculated withP. expansum, but not from healthy fruits, had endoPG and exoPG activity. Culture filtrates and extracts of diseased tissue were subjected to vertical starch-gel zone electrophoresis. The number, location (anodic, cathodic), electrophoretic mobility, and relative activity of sites of endoPG or exoPG activity were determined by the species, virulence or avirulence of the strain, source of organic carbon, and gel pH.

ISSN:0008-4026    

DOI:10.1139/b66-176

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

By two drought-hardiness tests, "time to death" and "soil-moisture content at the death point", Douglas-fir seedlings from three coastal sources were shown to be less drought resistant than those from five inland sources. Lethal needle-moisture contents, although not a proved test of drought hardiness, tend to confirm this conclusion. In addition, these lethal needle-moisture values, useful as an index of whole plant viability, were established for the various sources. Two of the coastal sources differed from five inland sources in the level of this value, but the lethal points for two other sources from the Oregon Cascade Range were similar to the five inland sources. Needle moisture appears to be a workable index for determining the whole plant viability except when the plant is very close to its time of death. Plants could also be classified into coastal and inland groups on the basis of their needle moisture under well-watered conditions, with the exception of seedlings from the Arizona source which are like the coastal group.

ISSN:0008-4026    

DOI:10.1139/b66-177

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Two new endemic species ofPhysaria, P. BelliiMulligan andP. RollinsiiMulligan, are described from Colorado. Both species are self-incompatible and their chromosome number is 2n = 8.

ISSN:0008-4026    

DOI:10.1139/b66-178

出版商:NRC Research Press    

年代:1966

数据来源: NRC

摘要:

Spore formation inDidymium iridis(Ditmar) Fries andDidymium nigripes(Link) Fries is generally preceded by both divisions of meiosis in the developing sporangium, and at the time of cleavage the spores are haploid with the 1C deoxyribonucleic acid (DNA) content. Synthesis of DNA begins soon after spore delimitation and the mature spores are in the haploid 2C category.The plasmodial nuclei were found to have twice the DNA content of the myxamoebae and the mature spores, hence karyogamy must precede plasmodial formation. The myxamoebal and plasmodial nuclei appear to have a very rapid rate of DNA synthesis, with an extended G2 phase of development; consequently myxamoebae are generally in the haploid 2C category and the plasmodial nuclei in the diploid 4C category.InD. iridisthe opposite mating types have different amounts of nuclear DNA, and the arithmetical sum of the mean DNA content of the mating types is equal to the mean DNA content of the plasmodial nuclei.InD. nigripesgrown on a medium containing 2% w/v glucose a large percentage of uninucleate amoeboid cells have a DNA content equal to that of the plasmodial nuclei. These cells are presumed to be zygotes.

ISSN:0008-4026    

DOI:10.1139/b66-179

出版商:NRC Research Press    

年代:1966

数据来源: NRC