摘要:

Attempts were made to isolate the substance or substances in whey responsible for the inhibition of infection with the barley stripe mosaic virus (BSMV). The fractions isolated were bioassayed to determine their potency. The bioassay method is described. Paper electrophoresis was used to indicate the composition of the fractions.Potent proteinaceous substances were obtained by dialysis, selective denaturation with ethanol, and fractional precipitation with ammonium sulphate. A progressive increase in potency was associated with an increase in the proportion of material that moved towards the cathode in electrophoresis at pH 8.6.Elutions from the electrophoretic bands gave evidence of very high potency in the two substances that moved towards the cathode but there was also evidence of degradation during elution. Quantitative bioassays of eluted materials were uncertain because of indications that the eluant had dissolved something from the paper.Development of electropherograms with Solway purple had no derogatory effect on the inhibitory material but ninhydrin destroyed all activity.

ISSN:0008-4026    

DOI:10.1139/b63-001

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Diaporthe phaseolorum(Cke. & Ell.) Sacc., the causal agent of pod and stem blight of soybeans and generally regarded as a facultative parasite, has been found to be pathogenic during the seedling phase. The fungus caused severe losses of germinating seeds and young seedlings. In 1959 more than 30% of the soybean seed crop in southwestern Ontario was infected, and germination was severely reduced.D. phaseolorumwas present in seed samples from this area in 11 of 13 years. Studies with a series of seed samples of varying levels of infection revealed that the fungus was still viable and pathogenic in the seed after storage for 2 years. However, during that time the levels of infection in most samples had decreased markedly whereas a concurrent increase in germinability indicated that infected seeds were killed during the germination phase. While several seed treatment fungicides were effective in increasing germination and emergence in heavily infected samples, none completely controlled the disease. At normal planting rates, yield was not affected by levels of seed infection up to 42% but the yield was significantly lower in a sample containing 73% infected seed. It is concluded that the disease may be important in the seed and seedling phases of host development.

ISSN:0008-4026    

DOI:10.1139/b63-002

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

The embryonic development of diploid and tetraploidMedicago sativafrom the formation of the zygote to mature seed is described and illustrated. The embryo reaches the global stage at 7 to 8 days; the heart stage at 11 to 13 days; and the torpedo stage at 14 to 16 days after pollination. Full size is attained at about 25 days but food reserves apparently continue to be stored and maturity may not be reached until about the 35th day.Pollination ofM. sativastigmas with pollen from highly incompatible species failed to produce mature embryos. Crosses involvingM. lupulinaproduced no sign of embryo development. However, whenM. arborea, M. blancheana, M. marina, M. platycarpos, M. rigidula, M. ruthenica, orM. scutellatawas used as a pollen parent the early stages of embryonic growth were initiated.

ISSN:0008-4026    

DOI:10.1139/b63-003

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Tris (hydroxyrnethyl) aminomethane was found to inhibit the growth ofHaematococcus pluvialisin ASMG medium, which is a modification of ASM medium. This inhibition could be reduced by increasing the calcium concentration of the medium. Other cations, either alone or in combination with calcium, had no effect on Tris toxicity. Tolerance towards Tris was increased in the presence of 5 mMcalcium when the initial pH of the medium was increased from pH 7.0 to 8.0 but pH had no effect on Tris tolerance in ASMG medium containing the normal level of calcium. These results withHaematococcusare compared with the results of a previous study onMicrocystis aeruginosa.

ISSN:0008-4026    

DOI:10.1139/b63-004

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

The activities of glutamic acid decarboxylase (GDC), glutamic–oxaloacetic transaminase (GOT), and glutamic acid dehydrogenase (GDH) were determined in cell-free extracts of healthy and rust-infected sunflower cotyledons and uredospores. Uredospore extracts contained an active DPN-linked GDH, but little or no GDC or GOT activity. The activity of GDC was lower and that of GOT higher in extracts of rust-infected tissue as compared to healthy tissue due to a redistribution of their coenzyme, pyridoxal phosphate. The activity of GDH was higher in 'rusted' extracts due to the presence of the similar fungal enzyme. It is suggested that this contribution of GDH by the fungus to the host–parasite complex alters the normal coenzyme pattern of other enzymes metabolizing glutamic acid.

ISSN:0008-4026    

DOI:10.1139/b63-005

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

When roots of tomato plants are infected withFusarium, systemic changes are induced in the activities of glycolic acid oxidase and glyoxylic reductase of the leaves. A marked decrease in glycolic acid oxidase activity is apparent 8–16 days after inoculation when the leaves show chlorotic symptoms. The depressed activity of this enzyme is due to a general decrease in the concentration of its flavin coenzyme, FMN. Both FMN and FAD begin to decrease after 8 days. On the other hand glyoxylic acid reductase shows an increased activity 20 days after infection. These alterations in enzymic activity result in a twofold accumulation of glycolic acid 20 days after infection even though the fungus is never present in the leaves.

ISSN:0008-4026    

DOI:10.1139/b63-006

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Data on the net production of oven-dry organic matter from 28 temperate angiosperm herbaceous species and 4 temperate arboreal species were analyzed to determine the relationship between below-ground and above-ground yearly increment. Mean yearly net herbaceous production (t/ha) was 3.9 for below-ground parts, 5.9 for above-ground parts, and 9.8 total. Mean yearly net arboreal production (t/ha) was 1.9 for below-ground parts, 8.9 for above-ground parts, and 10.8 total.The mean below-ground/above-ground ratio and mean below-ground production was significantly higher for herbaceous species. Mean above-ground production was significantly higher for arboreal species. There was no significant difference between total herbaceous and total arboreal production. Productivity comparisons based only upon above-ground parts are likely to be biased in favor of arboreal species.In herbaceous species, root production decreased with age and increased from fruit crops to root and tuber crops and the below-ground/above-ground ratio increased from moist to mesic to xeric species. Arboreal species were uniform in below-ground/above-ground ratios.

ISSN:0008-4026    

DOI:10.1139/b63-007

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

Morphological descriptions, chromosome numbers, and Canadian distribution ofCirsium muticumandC. discolorare given. The related speciesC. altissimumof the United States is similarly considered. The chromosome numbers of the species are:C. muticum,2n = 20;C. discolor, 2n = 20;C. altissimum, 2n = 18. Extra chromosomes, possibly to be considered as accessories, were found inC. muticumandC. discolor. A Florida collection ofC. muticumhad the apparently triploid number 2n = 30. The morphological and cytological evolution of the group is discussed.

ISSN:0008-4026    

DOI:10.1139/b63-008

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

A reappraisal is presented of the taxonomy of three of the four alternate-leaved species ofChrysospleniumoccurring in North America, namelyC. tetrandrum, C. iowense, andC. Rosendahlii, the latter a new species described for the first time. The investigation demonstrates that the species can be readily separated morphologically even as seedlings. Each morphological entity is characterized by a different chromosome number,C. tetrandrum2n = 24,C. Rosendahlii2n = 96.C. iowense2n = c.120, and a distinctive geographical distribution.C. iowense, which has on occasions been regarded as identical withC. alternifoliumvar.sibiricum, is retained as a species in the absence of a modern taxonomic analysis of the Old World speciesC. alternifolium.

ISSN:0008-4026    

DOI:10.1139/b63-009

出版商:NRC Research Press    

年代:1963

数据来源: NRC

摘要:

The root systems of 28 Douglas fir (Pseudotsuga menziesii(Mirb.) Franco) in four stands, aged 10, 25, 40, and 55 years, were excavated hydraulically to determine the rooting characteristics of trees in different crown classes at various ages. The extent, depth, configuration, rooting density, and mycorrhizal component of root systems were examined. The significance of the characteristics observed is discussed in relation to silviculture, nursery practice, and forest pathology.

ISSN:0008-4026    

DOI:10.1139/b63-010

出版商:NRC Research Press    

年代:1963

数据来源: NRC