Showing papers by "Agriculture and Agri-Food Canada published in 1984"
TL;DR: It is suggested that in P. hysterophorus, the water soluble plant metabolites play an important role not only in allelopathy and defense against herbivorous predators and diseases but also as autotoxins in population regulation and the timing of the germination processes.
113 citations
TL;DR: In this article, Humic acids and fulvic acids were extracted from six paleosols in Southern Italy, and the results showed that the preservation of the humic materials may have been due to low biological activity and/or to retention by amorphous minerals.
87 citations
TL;DR: Culturing the embryos for 24 or 48 h or treating the embryos with pronase, trypsin, or antiserum after virus exposure and washing reduced the number of embryos carrying virus and lessened the amount of virus on each of the embryos.
57 citations
TL;DR: In this article, a 13C CPMAS NMR study of samples of four organic soils differing only in copper content and degree of decomposition was conducted, and the distribution of intensity was determined by dividing the spectra into four regions, corresponding approximately to aliphatic, carbohydrate, aromatic and carboxyl carbons.
50 citations
TL;DR: It is indicated that proctolin cannot be transported via the haemolymph unless it is protected in some manner from enzymatic degradation.
49 citations
TL;DR: It is concluded that at marginally inhibitory concentrations host defence mechanisms contribute to metalaxyl activity, and the possibility that the stimulation of host defence responses inMetalaxyl-treated tissue may be due to inhibition of pathogen activities that suppress such responses in untreated tissues is discussed.
Abstract: Etiolated soybean hypocotyls (cultivar Altona) treated with the systemic fungicide metalaxyl [N-(2,6-dimethylphenyl)-N-(methyl-acetyl) alanine methyl ester] developed restricted brown lesions with high levels of the phytoalexin, glyceollin, when inoculated with zoospores of Phytophthora megasperma f. sp. glycinea (race 6, compatible). These responses were very similar to those in interactions of untreated hypocotyls with incompatible races. When hypocotyls were supplied with a mixture of metalaxyl, at marginally inhibitory concentrations, and glyphosate (N-phosphonomethylglycine), an inhibitor of the shikimic acid pathway, the effectiveness of the metalaxyl treatment was reduced, the lesions spread and glyceollin concentrations were lower. The effectiveness of metalaxyl added directly to the inoculum drop was also less in glyphosphate-treated hypocotyls than in control hypocotyls. Glyphosate did not affect the fungitoxicity of metalaxyl in in vitro growth assays. It is concluded that at marginally inhibitory concentrations host defence mechanisms contribute to metalaxyl activity. This is most probably due to glyceollin accumulation, but as levels frequently remained above ED90 values in spreading lesions and other aspects of host metabolism are known to be influenced by glyphosate, alternative explanations are possible. The possibility that the stimulation of host defence responses in metalaxyl-treated tissue may be due to inhibition of pathogen activities that suppress such responses in untreated tissues is discussed.
47 citations
TL;DR: In Quebec commercial apple orchards, spider populations are shown to have been depressed numerically by current pest management practices as mentioned in this paper, and spiders appeared to be more sensitive to insecticides than web-building species.
Abstract: In Quebec commercial apple orchards, spider populations are shown to have been depressed numerically by current pest management practices. Hunting species appeared to be more sensitive to insecticides than web-building species. There were large differences in spider distribution among orchards and years, although some consistent patterns were observed. Specimens from the following families were captured: Theridiidae, Linyphiidae, Lycosidae, Araneidae, Erigonidae, Clubionidae, Tetragnathidae, Dictynidae, Salticidae, Philodromidae, and Thomisidae. In orchards treated only for scab control or with only a single insecticide application for apple maggot control, spiders attained their maximal numbers in August. With two treatments for apple maggot control, spiders attained their maximal numbers towards the end of September.
43 citations
TL;DR: In the presence of H 2 O 2 as donor, horseradish peroxidase was used to catalyze the polymerization of seven monomeric phenols.
Abstract: In the presence of H 2 O 2 as donor, horseradish peroxidase was used to catalyze the polymerization of seven monomeric phenols. Yields of humic acid (HA) polymers from meta phenols—resorcinol and phloroglucinol—were insignificant. Of the five ortho and para phenols—phenol, catechol, hydroquinone, pyrogallol and 1,2,4-trihydroxybenzene—all except hydroquinone inhibited the enzyme at high concentration. The kinetics of polymerization of the ortho and para compounds were complex and dependent on the concentration of both electron acceptor and donor. The percentage yield of HA before dialysis was far greater from pyrogallol than from catechol or hydroquinone. After dialysis, the yield of the catechol HA was higher than those of the hydroquinone and pyrogallol HAs. A higher molecular weight for the catechol HA over those of the hydroquinone and pyrogallol HAs was also indicated by the lowest E 4 /E 6 ratio and highest free radical content. All of the synthetic HAs were relatively rich in free radicals, suggesting that their synthesis occurred via free radicals, i.r. and 13 C NMR spectra showed that the HAs were molecularly complex polymers or mixtures of complex aromatic structures rich in phenolic OH groups and to a lesser extent in CO 2 H groups. The only HA which showed fine structure in the i.r. spectrum was the pyrogallol HA; the presence of aryl ethers was indicated. 13 C NMR spectra showed that all synthetic HAs were highly aromatic, that aromatic rings of the initial phenols had been built into the HAs, but that molecular environments around phenolic OH groups had changed during the formation of the HAs.
42 citations
TL;DR: In this article, the interaction between aniline blue and curdlan, a (1 → 3)-β-d -glucan, has been studied using absorption and fluorescence spectroscopy.
39 citations
TL;DR: Species of Ceratozetes Berlese (CeratoZetidae) of Canada and Alaska are revised and four new species are proposed and those of C. virginicus and C. thienemanni are redescribed.
Abstract: Species of Ceratozetes Berlese (Ceratozetidae) of Canada and Alaska are revised. Four new species, Ceratozetes watertonensis , C. borealis , C. oresbios and C. pacificus are proposed, C. gracilis cuspidatus Jacot is elevated to specific status and redescribed, and C. gracilis (Michael), C. peritus Grandjean, C. kananaskis Mitchell, C. virginicus (Banks), C. mediocris Berlese, and C. thienemanni Willmann are redescribed. Immatures of C. borealis and C. pacificus are described and those of C. peritus , C. kananaskis , C. mediocris , C. gracilis , C. virginicus and C. thienemanni are redescribed. Ceratozetes jeweli Rockett and Woodring is synonymized with C. virginicus . A key to species from Canada and Alaska is given.
37 citations
TL;DR: Characterization of derived plasmids, carrying the col-imm operon but varying in the hic region, showed that the latter functions in lacuna production, colicin release, cell death, and lysis.
TL;DR: It was concluded that the corpus luteum can be maintained by the introduction of a viable embryo as late as day 17 of the cycle and that the decline in progesterone concentration at luteolysis is associated with a series of PGFM peaks which were absent or reduced in animals in which progestersone levels were maintained.
TL;DR: The antifungal activity of sesquiterpene lactones cannot be explained by the presence or absence of two potential active sites (the exocyclic methylene and, in pseudoguaianolides, a β-unsubstituted cyclopentenonel) but other functions must play a role in enhancing or reducing this activity.
TL;DR: Mites of the genus Trisetacus from North America are revised, and a key is presented for the 22 species recognized.
Abstract: Mites of the genus Trisetacus from North America are revised, and a key is presented for the 22 species recognized. A diagnosis and a review of host and distributional data are presented for each of these species. A comprehensive review of all nominate species and subspecies is included to facilitate appropriate usage of available names.
TL;DR: Membrane organization of the desiccation tolerant moss Tortula ruralis was studied in several intensely dehydrated states by (31)P nuclear magnetic resonance and ultrastructural analyses, which revealed that even at 75% RH (-400 bars), the moss cellular membranes retained extended phospholipid bilayers.
Abstract: Membrane organization of the desiccation tolerant moss Tortula ruralis was studied in several intensely dehydrated states (75% relative humidity [RH], 90% RH, plasmolysis in molar salt, freezing to −20°C) by 31P nuclear magnetic resonance and ultrastructural analyses. Both methods revealed that even at 75% RH (−400 bars), the moss cellular membranes retained extended phospholipid bilayers. Ultrastructural analyses of the fully hydrated moss showed an extensive proliferation of membrane vesicles in the endoplasmic reticulum. During dehydration, these vesicles form layers of membrane under the plasmalemma and in some cases appear to fuse with the surface membrane. This suggests that these vesicles may serve as a reservoir of membranes to accommodate for membrane surface area changes during desiccation and subsequent rehydration.
TL;DR: The nucleotide sequence of the newly characterized colicin E8imm gene is determined which exists in tandem with the colicIn E3imm gene in the: ColE3-CA38 plasmid ( Comparison of these immunity structures reveals considerable sequence divergence.
Abstract: We have determined the nucleotide sequence of the newly characterized colicin E8imm gene which exists in tandem with the colicin E3imm gene in the: ColE3-CA38 plasmid. Comparison of these immunity structures reveals considerable sequence divergence) but the ColE8imm gene is markedly homologous to the colicin E2imm gene from the ColE2-P9 plasmid.
TL;DR: Copper concentrations should be maintained at 100 ppm (gg Cu g−1 dry soil) in the surface layers of undecomposed peat soils, and 400 ppm in humified muck soils.
Abstract: Copper concentrations should be maintained at 100 ppm (gg Cu g−1 dry soil) in the surface layers of undecomposed peat soils, and 400 ppm in humified muck soils. The Cu supports plant nutrition, and inhibits enzymes that degrade the organic soils (Histosols). The required or extravagant applications of Cu may threaten groundwater quality if the Cu, or elements displaced by the Cu, moves downwards in the soils. To test this, powdered CUSO4.5H2O was applied to the top 15 cm of replicated microplots of organic soils to increase their Cu concentrations by 0, 150, 500, and 1500 ppm at field sites A (peat) and B (muck) in May 1978 and by 0, 100, 300, and 800 ppm at field site C (mucky peat) in 1979. Duplicate cores of up to 50 cm depth were taken in the spring of 1981 from each of the 56 microplots and analyzed. At all sites, none of the Cu additions caused significant displacement and downward movement of Ca, Mg, K, Fe, Mn, or Zn. There was a leaching of small fractions of the applied Cu down to 40 cm depth only when 1500 ppm of Cu was added to the humus-poor, acidic peat at site A. Some of the Cu applied at the 500 ppm rate at site A and 1500 ppm rate at site B was found in the 20 to 30 cm zone. At site C, none of the applied Cu moved from the top 20 cm (plow layer).
TL;DR: In this article, six Paleosols (buried soils) were extracted from six buried soils, ranging in radiocarbon ages from about 6000 to 29,000 yr. The N distribution (total N, amino acid-N, Amino acid-S, amino sugar-N and ammonia-N) in each Paleosol humic acid was determined.
TL;DR: The abdomen of female Pelecinus is uniquely and extremely modified for digging in soil, allowing vertical movement produced by anteriorly placed muscles acting through long tendons inserting on the adjacent succeeding segment.
Abstract: The abdomen of female Pelecinus is uniquely and extremely modified for digging in soil. Segments 2–7 are connected by sternite to sternite articulations allowing vertical movement produced by anteriorly placed muscles acting through long tendons inserting on the adjacent succeeding segment. Segments 3–6 have, in addition to the linkage allowing vertical movement, a detached, posterior section of the sternite that can rotate on a median ventral flexible attachment to the tergal margins. This linkage allows the posterior section of a sternite together with the succeeding segments to rotate through about 135 °relative to its tergite. Tergite 8 bears large spiracles completely covered by sternite 7. The ovipositor lacks the usual 3rd linkage between gonocoxite 9 and gonapophysis 9, allowing the depressor muscle of the gonapophysis to extrude the ovipositor directly backwards.
TL;DR: Germination of freshly harvested seeds of a non-dormant (ND) line (Stonehouse 319) of wild oats was inhibited by incubation of the seeds at relatively high temperatures of 25 and 30°C and thermo-Dormancy, induced during seasonal temperature fluctuations, may provide a survival mechanism for seeds.
Abstract: Germination of freshly harvested seeds of a non-dormant (ND) line (Stonehouse 319) of wild oats (Avena fatua L.) was inhibited by incubation of the seeds at relatively high temperatures of 25 and 30°C. The germination inhibition in these seeds appeared to be a case of thermo-inhibition which was the direct effect of hightemperature treatment (HIT), since it did not persist after transferring the seeds to an optimum germination temperature of 20°C. Even a prolonged HTT of 30°C for over 5 weeks did not prevent germination of about 80% of the seeds transferred to 20°C. However, in a significant proportion of the seeds, thermo-dormancy was induced by 10 days of HTT at 30°C if the seeds were then incubated at sub-optimal temperatures of 5 to 15°C. This thermo-dormancy would appear to be ‘restrictive’ in form, since its expression was restricted to very specific conditions. Relatively low inclubation temperaturs of 5 and 10°C markedly slowed germination whether HTT was applied or not. The results suggest that thermo-inhibition and thermo-dormancy, induced during seasonal temperature fluctuations, may provide a survival mechanism for seeds of such ND lines as Stonehouse 319.
TL;DR: Pelosoma pecki is described as new from specimens from the Florida Keys and from Mexico and the genus Genyon Smetana 1978 is placed in synonymy with Tectosternum Balfour-Browne 1958.
Abstract: Pelosoma pecki is described as new from specimens from the Florida Keys (Upper Matacumba Key) and from Mexico (Oaxaca). The genus Genyon Smetana 1978 (type-species Cercyon navicularis Zimmerman 1869, from eastern North America) is placed in synonymy with Tectosternum Balfour-Browne 1958 (type-species T. exstriatum Balfour-Browne 1958, from equatorial Africa). A lectotype is designated for Pelosoma prosternale Sharp 1882, and Pelosoma praecursor Smetana 1978 is placed in synonymy with P. prosternale Sharp 1882. Omicrus intermedius Smetana and the genus Cycrillum Knisch, with the species C. strigicolle (Sharp), are recorded for the first time from North America. Additional data on bionomics, geographical distribution, and synonymy of many species are presented.
TL;DR: Chosomal and numerical analyses suggest that Medicago ciliaris is the most primitive and M. granadensis the most derived species of theIntertextae.
Abstract: Karyotype and external morphological analyses were conducted onMedicago ciliaris, M. intertexta, M. muricoleptis andM. granadensis which comprise theIntertextae section of the genusMedicago. All species were found to have 2n = 16 chromosomes (= 2 ×), including one pair of satellite chromosomes in each respective complement. Karyotypic evolution in theIntertextae involves changes in absolute chromosome size and in centromeric and relative size symmetry. Numerical taxonomic analyses were conducted independently on 17 karyotypic features and on 16 features of external morphology. The results of the two sets of analyses proved comparable, withM. ciliaris andM. intertexta forming a fairly close pair, and the remaining two species appearing to have more distant relationships to each other and to the first pair. These observations are consistent with the infertility relationships and chorologies of the species. It is suggested thatM. muricoleptis andM. granadensis are derived from theM. ciliaris/intertexta species complex withM. granadensis arising fromM. muricoleptis, or these two species independently evolving from a common species complex. Chromosomal and numerical analyses suggest thatM. ciliaris is the most primitive andM. granadensis the most derived species of theIntertextae.
TL;DR: Adventitious shoots treated with commercial rooting powder and placed directly in mist frames produced much stronger root systems and could be adapted to greenhouse conditions without loss and the elimination of the in vitro rooting stage also simplifies the micropropagation program.
Abstract: The efficiency of commercial micropropagation programs for Begonia x hiemalis depends on the production of large adventitious shoots for easy handling and on effective rooting and acclimatization procedures. Maximum induction of adventitious buds on petiole segments occurred in response to NAA (0.1 mg, l-1) and BA (0.5 mg l-1), but continued shoot growth was limited. With a lower concentration of BA (0.1 mg l-1) fewer shoots were produced but shoot growth was enhanced. With a combined agar/liquid culture program the low BA (0.1 mg l-1) medium produced 50 percent more shoots larger than 1 cm than did the high BA (0.5 mg l-1) medium. In vitro rooted explants developed weak root systems and acclimatization losses occurred during adaptation to greenhouse conditions. Adventitious shoots treated with commercial rooting powder and placed directly in mist frames produced much stronger root systems and could be adapted to greenhouse conditions without loss. The elimination of the in vitro rooting stage also simplifies the micropropagation program.
TL;DR: The studies suggest that the site and mechanism of action of dieldrin and trans -aldrindiol upon the insect nervous system may be different, and the results are discussed in relation to the mode ofaction of cyclodiene insecticides.
TL;DR: Adult and larval character states of the subgenus Steropus are described, which include having the mandible strongly curved with wide retinaculum in the first instar and a membranous area on antennomere I.
Abstract: The subgenus Steropus Dejean of the genus Pterostichus Bonelli (Coleoptera: Carabidae) is redefined. The subgenus includes 24 species occurring in the Palaearctic and Nearctic regions. Eight species previously included in Steropus, P. catalonicus K. Daniel, P. ferreri (Espanol andMateu), P. galaecianus Lauffer, P. ghilianii (Putzeys), P. globosus (Fabricius), P. insidiatrix (Piochard de la Brulerie), P. madidus (Fabricius), and P. riffensis (Antoine), are transferred to the subgenus Corax Putzeys (formerly considered as a junior synonym of Steropus) which is recognized as a valid taxon. Refonia Casey, with two North American species, Eosteropus Tschitscherine (type-species: Platysma creperum Tschitscherine, present designation), with four Asiatic species, and Steropinus Lutshnik, with one Asiatic species, are placed in synonymy with Steropus. Adult and larval character states of the subgenus Steropus are described. Larvae of Steropus are synapomorphic with those of P. (Corax) madidus and P. (Feronidius) melas Creutzer in having the mandible strongly curved with wide retinaculum in the first instar and a membranous area on antennomere I.