摘要:

Seedlings of 10 tree species were tested under two widely different photo periodic conditions in environment otherwise near optimum. The amount of light given to the plants was the same under both conditions. Under the conditions simulating long photoperiods, the seedlings of all the species grew well and continued their growth during the 8-month experimental period. Under the short photoperiod, the following species remained nearly or fully dormant for several months beginning soon after germination:Larix laricina(Du Roi) K. Koch,Ulmus americanaL., and two provenances ofPicea glauca(Moench) Voss; the following species either remained nearly dormant or grew significantly slower than under the long day conditions:Betula luteaMichx. f.,B.verrucosaEhr., andPinus banksianaLamb.;P.resinosaAit. was considered sensitive to photoperiods but its responses in appearance and growth were small;Caragana arborescensLam.,Thuja plicataDonn, andAcer negundoL. showed no significant response.

ISSN:0008-4026    

DOI:10.1139/b57-014

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

Seed development was followed from fertilization to maturity. Pollen tubes required about 4 days to grow from stigma to ovule. In some plants, particularly bagged ones, nucellar cells remained alive and contents of the embryo sac degenerated. Many ovules did not develop. Seeds were counted and sorted in a random representative collection of 1075 berries. The average number of seeds per berry was 64.2. Of these 49.9 (or 77.7%) were imperfect. More complete pollination increased the percentage of normally developing ovules. Development of perfect seeds followed a familiar pattern. Unfamiliar features were noted as follows: 1. Degeneration of cells at both micropylar and chalazal ends resulted in a homogeneous plasma. This plasma formed strands across haustoria and almost completely surrounded the zygote. 2. Micropylar endosperm cells formed a dense plug. Developing embryos may have had difficulty in penetrating this plug. 3. Many embryos had died at some stage of development. 4. A conspicuous integumentary tapetum was present until the endosperm was about half its final size.Embryo development was the "soland" type. Mature seeds were "axile linear". Imperfect seeds were chiefly of two types: (a) medium sized and solid with middle integumentary layers lignified, or (b) small and collapsed with all tissues inside seed coat disintegrated. No imperfect seed had an embryo.

ISSN:0008-4026    

DOI:10.1139/b57-015

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

The nature, causes, and rate of pathological deterioration of jack, red, and white pine killed by fire in the Mississagi region of Ontario in 1948 were studied to determine the practicability and probable duration of profitable salvage operations in such stands. Blue and brown sapwood stains appeared in all species 1 year after the fire, and became extensive during the succeeding 3 years. Sap rot was first noted 2 years after the fire; 5 years after the fire most of the sapwood was affected, and in some cases this rot extended into the heartwood. Three fungi,Peniophora gigantea(Fries) Massee,Polyporus ancepsPeck, andPolyporus abietinusDicks. ex Fries, were isolated consistently from white sap rots, whileFomes pinicola(Sw.) Cooke andFomes subroseus(Weir) Overh. were recovered from many of the brown sap rots. The increase in the volume of heart rot encountered during the course of the study, chiefly associated withFomes pini(Thore) Lloyd, was much greater than that observed in living pine over a similar period, and for this reason the excess was considered as a form of deterioration. The average rate of radial penetration of visible deterioration was significantly faster in trees with widely spaced annual rings in the outer portion of the bole than in slow-growing trees. Variations in the severity of burn in individual trees or stands apparently had little effect on the rate of pathological deterioration.

ISSN:0008-4026    

DOI:10.1139/b57-016

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

The perfect state of a species ofLeptographiumLag. & Melin has been placed in the new genusEurophiumof the Eurotiaceae and described asEurophium trinacriformesp. nov. Perithecia were found on the trunks of dead or dyingPinus monticolaDougl. and a method was developed for their production in culture.

ISSN:0008-4026    

DOI:10.1139/b57-017

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

It was ascertained that the species from which Grimm alfalfa presumably originated, viz.;Medicago sativaandM.falcata, may freely exchange genetic material without evidence of a sterility barrier. Consequently a polyhaploid obtained of Grimm may be considered as comparable to natural diploids.The polyhaploid showed some impaired morphological and physiological characters and pronounced meiotic abnormalities. The single genome (x = 8) of the polyhaploid was found to be almost non-functional. Inheritance of purple color indicated a potential autotetraploid mode of transmission of characters.The polyhaploid was raised back to the tetraploid chromosome level by chromosome doubling and compared to its original and to Grimm. The somatically chromosome-doubled counterpart was found to be a close replica of the original polyhaploid. An assumption that an accumulation of detrimental recessive genes may remain latent at the tetraploid level, and may be expressed upon later reduction to half of the genic variability as in the polyhaploid and its somatically chromosome-doubled derivative, is advanced to explain the observed phenomena.Phylogenetic, breeding, and culture-historical aspects of the results are discussed.

ISSN:0008-4026    

DOI:10.1139/b57-018

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

The following parasitic fungi are newly reported from Nova Scotia:Peronospora cakilesSavile sp. nov. (onCakile edentula),Taphrina tosquinetii(West.) Magn.,Stigmatea robertianiFr.,Pucciniastrum potentillaeKom.,Puccinia calcitrapaeDC,Puccinia praegracilisArth. var.cabotianaSavile var. nov. (onHierochloë odorata, aecia onHabenaria psycodes),Uromyces erviWest.,Cercospora pontederiaeEll. & Dearn.,Isariopsis bulbigera(Fckl.) Savile comb. nov. (=Ovularia bulbigera(Fckl.) Sacc),Ramularia oxalidisFarl.,Ramularia pusillaUnger (=Ovularia pusilla(Unger) Sacc.),Ramularia rubella(Bon.) Nannf.,Ramularia subsanguinea(Ell. & Ev.) Savile comb. nov.,Marssonina sennenisGonz. Frag.,Septogloeum potentillaeAllescher, andSeptoria levisticiWest. The status of the generaOvulariaandRamulariais briefly discussed. A few new host records of other fungi are included.

ISSN:0008-4026    

DOI:10.1139/b57-019

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

The presence of an active cyclophorase system capable of oxidizing the principal acids of the Krebs acid cycle was demonstrated in mitochondria from hypocotyls and cotyledons of tomato seedlings. The optimum conditions for active mitochondrial preparations and maximum enzyme activity, especially for the succinoxidase system, were determined and are reported.Lycomarasmin and fusaric acid, two toxins produced byFusarium oxysporumf.lycopersici, inhibit the succinoxidase and cytochrome oxidase activity of the mitochondria at a concentration of 10−2 M. The inhibition was overcome by the addition of catalytic amounts of cytochromec. No effect was observed on succinic dehydrogenase. It was concluded that the toxins inhibit enzyme activity by affecting the integrity of the mitochondria allowing diffusion of cytochromecfrom active sites. The role of the toxins inFusariumwilt of tomatoes is discussed.

ISSN:0008-4026    

DOI:10.1139/b57-020

出版商:NRC Research Press    

年代:1957

数据来源: NRC

摘要:

Complete seasonal patterns of moisture content of the wood and bark ofBetula lutea(which resembles other species of birch) and ofTsuga canadensisare given, along with those for sapwood and heartwood ofAbies balsameaandPicea rubens. Incomplete seasonal data are also presented on the moisture content of the wood ofPicea glaucaandThuja occidentalis.Minor variations in the water content pattern of yellow birch due to precipitation, evapotranspiration, and winter insolation are described. These variations, examined in the light of climatic data, lend little support to the view that birch dieback is due to an increase in temperature or to drought, except possibly through their effects on some unknown biotic factor.The practical aspects of tree water content studies are discussed with particular reference to the questions of flotation and sinkage of logs.

ISSN:0008-4026    

DOI:10.1139/b57-021

出版商:NRC Research Press    

年代:1957

数据来源: NRC