摘要:

The dephosphorylation of phosphoglyceric acid was tested under a variety of conditions. Hydrolysis of the ester by leaf homogenates was relatively slow, even when conditions favored enzymatic activity, and was not detected when frozen homogenate was extracted by boiling 80% ethanol. The results suggest that glyceric acid recovered in ethanol-soluble extracts of leaves following short-term photosynthesis experiments is not normally derived from phosphoglyceric acid. The route proposed for the synthesis of glyceric acid is related, with particular reference to soybean leaf, to an alternate pathway for photosynthetic assimilation which does not utilize phosphoglyceric acid.

ISSN:0008-4026    

DOI:10.1139/b61-001

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

A comparison was made of growth factor requirements and growth factor synthesizing capacity of bacteria from the root surface and from the seeds of flax varieties resistant and susceptible, respectively, to wilt caused byFusarium oxysporumf.lini. The percentage of bacteria from both root and seed which required growth-promoting substances was greater with the resistant ('Bison') than with the susceptible ('Novelty') variety. On the other hand bacteria capable of synthesizing growth factors were proportionately more abundant with the susceptible variety. The findings indicate a more pronounced rhizosphere effect exerted by the susceptible than by the resistant variety, and point to circumstances that favor a greater accumulation (or 'turnover') of vitamins and related substances at the root surface of susceptible plants.Two strains ofFusarium oxysporumf.linicapable of inducing wilt required no vitamins for growth; thiamine had a depressing effect. Both strains were able to synthesize various growth factors, though in different degree. Culture filtrates of bacteria from roots of the two varieties of flax showed no difference in their effect on growth ofFusarium; however, bacteria from the resistant variety showed somewhat greater ability to depressFusariumthan those from the susceptible. Though the findings do not constitute evidence of any relationship between differences in growth factor relationships to pathogenic potential ofFusarium, they suggest the value of considering growth-promoting substances in studies of the effect of nutrition on the activity of soil-borne pathogens.

ISSN:0008-4026    

DOI:10.1139/b61-002

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

The morphology and specific differences ofCirsium undulatum(Nutt.) Spreng. and ofC. flodmanii(Rydb.) Arthur are described and their Canadian distributions are reported in detail. The chromosome numbers areC. undulatumf.undulatumand f.albumFarwell, 2n = 26;C. flodmaniif.flodmaniiand f.albiflorumD. Löve, 2n = 22. The origin of four North American species ofCirsiumthat do not follow the world-wide base number 17 is discussed; it is postulated that reduction in number has occurred by translocations. The chromosomes of species with reduced numbers are larger than those of the unreduced species but the total length of the chromosomes of both groups is approximately the same.

ISSN:0008-4026    

DOI:10.1139/b61-003

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Samples of pollen of three genera (Populus, Pinus, andTypha) which are normally shed at different times during the growing season were placed concurrently in four habitats (a pond, a lake, a swamp, and a bog). Their decomposition was traced through the summer and autumn of two seasons. The study shows that there is considerable variability in fossilization of pollen under identical conditions, and that the decomposition of the same pollen is dependent on the habitat, which affects not only the rate of decomposition but also the processes involved.

ISSN:0008-4026    

DOI:10.1139/b61-004

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

A new allopolyploid species ofCelosia, namely,C. whiteii, collected in Malaya and originating from a natural cross betweenC. argenteaL. (2n = 72) andC. cristataL. (2n = 36), has been described and the somatic chromosome number determined as 2n = 108. A somatic chromosome number of 2n = 18 has been determined for another species ofCelosia, namely,C. trigynaL. The basic chromosome number for the genus has been determined as nine. Of the four species ofCelosiaso far studied cytologically, each represents a different level of ploidy, from diploid (2x) to dodecaploid (12x).

ISSN:0008-4026    

DOI:10.1139/b61-005

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

The maximal chlorophyll contents reached during the growth of each of the first three leaves of Marquis wheat increased linearly with daylength, when the plants were grown from germination under illumination of 1750 ft-c intensity for daily periods of 8, 16, or 24 hours. This effect of daylength was also seen when chlorophyll concentration was expressed on a unit leaf area or fresh weight basis, and was related to increased leaf thickness at the longer daylengths. The increased chlorophyll content and concentration under long daylengths could not be duplicated by extending short daylengths with low-intensity supplementary light. Previous experiments suggest that the control of chlorophyll content by daylength is through the control of leaf thickness by the total amount of daily energy.The ratio of chlorophyllatobin mature leaves did not vary with daylength. There was also no change in the maximal chlorophyll concentration of leaves mature at the time of floral initiation compared with those mature in the vegetative stage of development.

ISSN:0008-4026    

DOI:10.1139/b61-006

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

The behavior of two soil saprophytes,Trichoderma virideandTrichocladium asperum, and two root-infecting fungi,Ophiobolus graminisandFomes annosus, was compared under various conditions in laboratory culture.On an agar-solidified organic medium optimum temperatures for growth were approximately:T. viride25–30 °C,T. asperum20–25 °C,O. graminis20–25 °C,F. annosus25 °C.T. viriderapidly outgrew the other fungi in the optimum range but this relationship changed at lower temperatures, its growth rate being equalled by that ofO. graminisat 10 °C.T. viridewas the only fungus to grow at 35 °C. In a synthetic liquid medium adjusted to pH values from 3.0–7.0 with a citrate–phosphate buffer, growth ofO. graminisandF. annosuswas sharply reduced at pH values below 5.0.T. viridemade good growth at pH 3.1 and reduction in growth ofT. asperumoccurred only below pH 4.0. Both parasites required thiamine for growth in a synthetic medium andO.graminisalso required biotin; in addition they showed a preference for organic as opposed to inorganic nitrogen sources.T. virideandT. asperumgrew well with KNO3as nitrogen source and neither required vitamins.D-Glucose,D-fructose, andD-mannose were readily utilized, andD-arabinose poorly utilized, by all four fungi. Utilization of other hexoses, pentoses, disaccharides, and polysaccharides varied considerably between the fungi.The relationship of the results obtained to the observations of others on the ecology of soil fungi is discussed and the possibility that combinations of physical and nutritional factors may favor specific fungi in the soil is considered.

ISSN:0008-4026    

DOI:10.1139/b61-007

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

In two hybrids betweenTriticum timopheeviZhuk. andT. durumDesf., which have irregular meioses, metaphase I was subdivided into four developmental stages, early, medium, late, and very late. This subdivision was based on the presence in the anthers of other stages that occurred together with metaphase I. It was then discovered that in metaphase I cell populations there was a progressive increase of univalents from the early and medium stages to the very late stage. This phenomenon can be explained on the assumption that metaphase I is of shorter duration in the less irregular cells which pass into anaphase I earlier than the more irregular cells. As a consequence of this developmental phenomenon at metaphase I, the anaphase I and telophase I cells in the late anthers contained fewer lagging chromosomes than the anaphase I and telophase I cells in the very late anthers. Despite these numerical differences, the degrees of lagging were remarkably similar in both stages; approximately 70% of these univalents lagged at late and very late stages in both hybrids.During metaphase I many univalents of the irregular cells moved towards the equatorial plate, became oriented, and lagged at anaphase I and telophase I. It was found that the univalents of the least irregular cells accumulated somewhat faster at the plates than those of the more irregular cells.Considering the relationships between all of the available data, the hypothesis is advanced that when a certain number of univalents have accumulated at the equatorial plate a state of equilibrium is established and anaphase I is initiated. On the basis of this hypothesis an explanation of the trends observed at metaphase I is given.

ISSN:0008-4026    

DOI:10.1139/b61-008

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

A method forin situinoculation of Scots pine roots withFomes annosusis described. Replacement of the fungus within the inoculum and rate of movement of the fungus on to the root surface were two important considerations in the development of a successful inoculation technique. Preliminary observations on host vigor, food-base size, and resin production as factors influencing growth ofF. annosusare noted.In laboratory and field trials, spores ofFomes annosuscaused infection of Scots pine roots only when sown on woody tissues exposed by cutting. A method is described whereby it was possible to observe development of spores on the surface of pine roots. The influence of microbiological and nutritional factors on infection of roots byF. annosusspores is discussed.

ISSN:0008-4026    

DOI:10.1139/b61-009

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Chromosome numbers and voucher specimens are recorded for some Canadian and Alaskan collections and a few mainland American collections ofPoaandPuccinelliawhich belong to the tribeFESTUCEAE. The somatic chromosome numbers of the following are recorded: (1)Poa agassizensis, 2n = ca. 56;P. alpina, 2n = 32, 33, 39, and 42;P. ampla, 2n = 62;P. annua, 2n = 28;P. arctica, 2n = 56, 63, 70, ca. 75, 78, 82, 85, 86, and 106;P. arida, 2n = ca. 76;P. canbyi, 2n = 56, 70, and ca. 98;P. cusickii, 2n = 56, and 59;P. eminens, 2n = 42;P. fernaldiana, 2n = ca. 42;P. glauca, 2n = 42, 50, 56, 64, 65, 70, 75, and 78;P. glaucantha, 2n = 44;P. glaucifolia, 2n = 56, ca. 70, and ca. 100;P. interior, 2n = 28, 34, 42, and 56;P. juncifolia, 2n = ca. 60;P. leptocoma, 2n = 42;P. nervosa, 2n = 56, and ca. 74;P. palustris,2n = 28, 30, and 32;P. pratensis, 2n = 28, 42, 44, 56, ca. 66, 67, 70, 74, ca. 78, ca. 82, 84, 86, 88, and ca. 124;P. saltuensis, 2n = 28;P. secunda, 2n = 42, 56, 70, ca. 78, 80. and ca. 90;P. stenantha, 2n = 42; andP. trivialis, 2n = 14.(2)Puccinellia ambigua, 2n = 56;P. americana, 2n = ca. 42 and 56;P. angustata, 2n = 42;P. borealis, 2n = 42;P. bruggemannii, 2n = 28;P. cusickii, 2n = 28;P. distans, 2n = 42;P. glabra, 2n = 42 and 56;P. hauptiana, 2n = 28;P. laurentiana, 2n = 42 and 56;P.longiglumis, 2n = 56;P. lucida, 2n = 42 and 56;P. nuttalliana, 2n = 42;P. ×phryganodes, 2n = 21;P. vaginata, 2n = 56; andP. vahliana, 2n = 14.

ISSN:0008-4026    

DOI:10.1139/b61-010

出版商:NRC Research Press    

年代:1961

数据来源: NRC