摘要:

Clumps ofGracilaria confervoides(L.) Grev. several meters long and several kilograms in weight have been found growing on clean sand bottom. These plants do not arise from the usual discoid holdfast on a buried stone, etc., but each is anchored by enwrapment of main strands to the tube of a worm,Diopatra ornataMoore. This enwrapping was observed to occur by mechanical obstruction of loose hanks of the alga by projecting worm tubes during extreme low tides on winter nights. In three months the alga was cemented to the tube by unexplained action. A coaction of alga and tube worm apparently exists that establishes plant shelter for small animals on an otherwise unsuitable substratum, thus increasing the complexity of the community on such sites. It is suggested that perennating marine algae produce much the same seasonal shelter for animals as do the deciduous plants of terrestrial communities.

ISSN:1923-4287    

DOI:10.1139/cjr50c-026

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Young Douglas fir in British Columbia sustained damage fromPhomopsis lokoyaeHahn during the winter of 1948–49. Damage in the form of annual stem and branch cankers, leader die-back, and stem girdling was confined to trees, or parts of trees, 4 in. in diameter or less. Fungus activity was confined to Douglas fir bark and cambium tissues for the single dormant season. Outbreaks of the fungus are recurrent in British Columbia, reaching epidemic proportions only at irregular intervals.

ISSN:1923-4287    

DOI:10.1139/cjr50c-027

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

An experiment to measure the daily potential evapotranspiration from vegetation-covered soil surfaces was conducted in Toronto during the 1947, 1948, and 1949 growing seasons. The potential evaporation from moist bare soil was also measured and compared with the evaporation from dry soil. Results indicate that the Thornthwaite formula for computing potential water loss is valid at this latitude for both vegetation-covered and moist soil. When drying of the surface soil occurred, the water loss was diminished.

ISSN:1923-4287    

DOI:10.1139/cjr50c-028

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

The pasmo pathogen sporulated freely on potato dextrose agar containing yeast extract. Spores suspended in water with gelatin as a spreader–sticker were sprayed onto flax plants at different stages of growth in field plots. Heaviest infections of pasmo resulted from inoculations at the flowering stage, lighter infections from inoculations on seedlings, and lightest infections from inoculations on ripening plants. Diluting the concentration of spores in the inoculum reduced disease intensity. The four flax varieties in the tests differed in reaction to pasmo. In decreasing order of susceptibility they were: Viking, Redwing, Royal, and Crystal. Heavy infections of pasmo caused premature ripening and reduced the seed yield and weight per thousand kernels of all four varieties. The effects of pasmo infection on seed yield and kernel weight were similar to those caused by a hot, dry climate, and by flax rust. Seed yield and kernel weight were reduced most markedly by inoculation at the flowering stage, less severely by inoculation at the seedling stage, and least of all by inoculation at the time of ripening. Seed yield and kernel weight from plots inoculated when the plants were ripening did not differ significantly from the uninoculated checks. Highly significant positive correlations between the data for seed yield and kernel weight indicated that much of the loss in yield resulted from a reduction in the size of individual seeds.

ISSN:1923-4287    

DOI:10.1139/cjr50c-029

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Fragmented spinach chloroplasts were stored for one year in 0.5 Msucrose at −40 °C. with almost negligible losses of photochemical activity. Thawed chloroplasts and freshly isolated chloroplasts showed similar rates of deterioration at 10 °C. Washed chloroplasts did not show as high retention of activity during low temperature storage as crude chloroplast suspensions. High retentions of activity were observed with chloroplasts from different plant species, as well as with different oxidants. The activities of subsamples that were frozen and thawed in a standard way agreed within 5%. Deterioration during lyophilization of chloroplasts occurred chiefly during the early stages of drying, and was lessened by sucrose. The stability of lyophilized chloroplasts in storage varied directly with the degree of desiccation and inversely with the storage temperature; little deterioration occurred in thoroughly dried chloroplasts during lengthy storage at or below 5 °C.

ISSN:1923-4287    

DOI:10.1139/cjr50c-030

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

In the following contribution four species ofPeniophoraare described, illustrated, and discussed, which appear to represent a closely related group. These arePeniophora rimicola(Karst.) Höhn. & Litsch.,P.pruinosa(Pat.) comb. nov.,P.pulverulenta(Litsch.) comb. nov., andP.praeteritaproposed as a new species. These species have several characters in common. All are mucous-gelatinous when fresh, drying to a vernicose film. In all of them simple, capitate, or apically lobed cystidioles are present and the spores show some degree of roughening when mounted in Melzer's solution. All but one,P.pulverulenta, have long emergent cystidia which may be slightly thickened at the base.

ISSN:1923-4287    

DOI:10.1139/cjr50c-031

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Intensive surveys of the physiological races ofCladosporium fulvumCke. have been carried out during the past decade in southwestern Ontario, as a result of which seven such races have been identified. These are separated by differential reactions of the following hosts:Lycopersicon esculentumMill. varieties Potentate, Stirling Castle, Vetomold, V-121, and V-473;L.pimpinellifolium(Jusl.) Mill., Vineland, No. 160 and No. 11-22-15 strains;L.hirsutumHumb. and Bonpl. andL.hirsutumvar.glabratumMuller. Evidence is presented that only two of these races existed when the surveys began and that the other five have arisen, probably through mutation, during the period under study. There is further a strong suggestion that the stimulus responsible for these mutations is somehow related to the colonization of an incompatible host by a race which remains stable pathogenically while in association with a susceptible host. Comparable mutants have not been encountered under experimentally controlled conditions. A perfect stage has not been found or induced to form inC.fulvum. A limited number of types of cultural mutants are produced consistently and these have been studied with respect to variability and the factors initiating them. Such mutants frequently do not form spores and in most instances have a reduced sporing potential; they are unchanged in pathogenicity or are slightly less aggressive than the parent to all the resistant hosts. In mixed cultures of races 1 and 5 and 1 and 7, the components survived several transfer generations both in culture and on a susceptible host.

ISSN:1923-4287    

DOI:10.1139/cjr50c-032

出版商:NRC Research Press    

年代:1950

数据来源: NRC

摘要:

Two species ofGelasinosporaare described for the first time.G.adjunctaCain, a heterothallic species with eight-spored asci, was grown in moist chambers on dung from Germany and Quebec.G.retisporaCain, distinguished by means of the large angular pits in the ascospore wall was isolated in culture from seeds of Swiss chard from Holland and from apple twigs in Quebec.G.tetraspermaDowding has been found in moist chambers on dung from Ontario, Quebec, Venezuela, and Germany and isolated from seeds from Quebec. Notes are added regarding the disposition ofAnthostomella destruensShear andSordaria uvicolaViala and Marsais.

ISSN:1923-4287    

DOI:10.1139/cjr50c-033

出版商:NRC Research Press    

年代:1950

数据来源: NRC