Showing papers by "Agriculture and Agri-Food Canada published in 1977"

Influence of heat treatment on the quality of vegetables: changes in visual green color

Abstract: Frozen asparagus, green beans, and green peas were properly defrosted and packed in 211 × 011 cans together with city water. The prepared samples were then heat processed at 175–300°F for 0.5–20 min. The tristimulus values of puree prepared from heat processed vegetables were determined by using a color difference meter. The ratio -a/b was used to determine the values of reaction kinetic parameters, D and z, for the discoloration of the vegetables since this ratio was closely related to the visual color of green vegetables. A D value was estimated from the slope of a linear portion of a curve. This curve was obtained by plotting the common logs of -a/b against isothermal heating times. A z value was determined from the slope of a thermal death time curve, which was obtained by plotting log1 0 D against temperature. The z values for the discoloration of asparagus, green beans and green peas were found to be equal to 75 (°F), 70 and 71, respectively. Apparent activated energies for changes in visual green color, which was represented with -a/b, were estimated by assuming first order reaction kinetics. These energies for asparagus, green beans, and green peas were respectively equal to 18,080 (cal/mole), 19,800 and 15,200.

Description and evaluation of a sensible heat flux detector

Abstract: An eddy-correlation method is the basis of a newly-developed sensible heat-flux detector which collects air temperature information proportional to the vertical wind speed in two electronic counters, one for upflow and one for downflow. The current model uses fast-responding sensors for vertical velocity and air temperature, but the principle should be applicable to the measurement of other kinds of fluxes. Values of sensible heat transport above bare soil and above grass have been determined, from which a sampling duration of one hour has been found to be suitable. The system provides a relatively simple way to measure sensible heat fluxes and to determine the suitability of this flux technique for wider application.

Simultaneous Inhibition of Linolenic Acid Synthesis in Winter Wheat Roots and Frost Hardening by BASF 13-338, a Derivative of Pyridazinone.

Abstract: Treatment of 12-day-old winter wheat ( Triticum aestivum ) plants with BASF 13-338 {4-chloro-5 (dimethylamino)-2-phenyl-3(2H)-pyridazinone} 36 hours before frost hardening simultaneously and completely inhibits accumulation of linolenic acid in the roots during the hardening period and the acquisition of frost resistance. Increased unsaturation of fatty acids is therefore probably an important part of the mechanism of cold adaptation in winter wheat. BASF 13-338 also prevents the increase in per cent dry weight in roots and shoots during hardening and causes a decrease in root lipid phosphorus and total fatty acids. The concurrent increase in linoleic acid and decrease in linolenic acid in the treated plants, while the level of the other fatty acids is but little affected, suggest that BASF 13-338 specifically inhibits linoleic acid desaturase.

Role of Phenolic Inhibitors in Peroxidase-mediated Degradation of Indole-3-acetic Acid.

Abstract: 7-Hydroxy-2,3-dihydrobenzofuran derivatives, metabolites of a carbamate insecticide carbofuran, and five other phenolic inhibitors of indoleacetic acid (IAA) oxidase interfered with IAA-induced spectral change in the Soret band of horseradish peroxidase (HRP). The onset of IAA degradation required transformed HRP intermediates. The inhibitors, when added before IAA, protected HRP from reacting with IAA, thus preventing formation of highly reactive enzyme intermediates, and consequently, IAA degradation. When added after IAA, the inhibitors quickly reversed the IAA-induced spectral change of HRP and inhibited further IAA degradation.The phenolic inhibitors differed in stability and reactivity. 7-Hydroxy-2,2-dimethyl-2,3-dihydrobenzofuran, 3,7-dihydroxy-2,2-dimethyl-2,3-dihydrobenzofuran, catechol, protocatechuic acid, caffeic acid, ferulic acid, and scopoletin belonged to one group which produced only a temporary inhibition to IAA-induced spectral change of HRP and IAA degradation since the inhibitors were metabolized in the reaction. The length of the lag was dependent on the IAA, inhibitor, and enzyme concentrations. 3-Keto-7-hydroxy-2,2-dimethyl-2,3-dihydrobenzofuran and 3-keto-carbofuran belonged to the other group which produced a persistent inhibition.Degradation of IAA required both the heme group and apoprotein of HRP. Reconstituted enzyme from bovine hemin and apoprotein or HRP after unfolding by urea or guanidine treatment were inhibited by the inhibitors in a way similar to the native HRP. The inhibition was reversible by higher concentrations of IAA, but the plot of 1/v versus 1/s and 1/v versus i were curvilinear, reflecting the complex nature of a competitive inhibition.

Effects of fungicides on the microbiology and biochemistry of soils — a review

Abstract: Eingriffe von Fungiziden in die Mikrobiologie und Biochemie von Boden — eine Ubersicht Bereits im Jahre 1970 war das Fungizid Captan das in der Anwendung Dritthaufigste Pestizid in den U.S.A. Damit soll die zunehmende Bedeutung der Fungizide in der Pedosphare betont werden und eine zusammenfassende Abwagung der verschiedenen Wirkungsweisen dieser Pestizide (a) auf die Besiedlungsdichte an Bodenpilzen, (b) auf die einzelnen Pilzarten in Boden, (c) auf die bakterielle Gesamtflora (heterotrophe und autotrophe Organismen) und (d) auf die Actinomyceten rechtfertigen. Die Applikation von Fungiziden bewirkt haufig eine vorubergehende Gleichgewichtsstorung der Mikroflora. Wohl am starksten reagieren die Pilze, einmal in einer starken Abnahme ihrer Gesamtdichte, zum anderen in einer Vermehrung bestimmter Gattungen (oft Trichoderma und Penicillium spp.). Unter den Bakterien sind es insbesondere die autotrophen Nitrifikanten (Nitrosomonas spp. und Nitrobacter spp.), welche empfindlich auf die Anwendung von Fungiziden reagieren. Die Hemmung der Nitrifikation macht sich vielfach in einer NH4-Akkumulation bemerkbar. Gelegentlich auch konnen geringe Applikationsraten die Nitrifikation fordern. Aber auch die phosphatauflosenden Bakterien scheinen positiv beeinflust zu werden, was sich in einer Zunahme der CaCl2-loslichen Bodenphosphate niederschlug. Aber auch andere Kationen wie K und Mg konnen nach einer Fungizidbehandlung (Benomyl) besser pflanzenverfugbar werden. Fungizide konnen daruberhinaus die Zersetzungsrate von Streustoffen signifikant beeinflussen, einmal durch Verminderung der zellulolytischen Pilzflora, zum anderen durch Schwachung der Enzymaktivitaten beim Abbau von Chitin, Zuckern, organischen Phosphaten und Harnstoff. Schlieslich scheinen Fungizide auch das Pflanzenwachstum zu fordern, und dies nicht nur durch Eliminierung von Pflanzenschadlingen. Demgegenuber steht die Beobachtung, daO die Rhizospharenflora so in Mitleidenschaft gezogen werden kann, daB die pathogenen Organismen in ihrem Invasionsvermogen gestarkt werden. Die langfristige Wirkung von Fungiziden auf Boden und ihre Eigenschaften ist durchaus noch luckenhaft. Wenig bekannt ist auch uber die gunstige bzw. ungunstige Wechselwirkung von Fungiziden mit anderen Pestiziden in Boden. Der steigenden Pestizidanwendung im Rahmen der Nahrungsmittelversorgung mus kunftig ein verstarkter Informationsstrom uber die Wirkungsweise und Auswirkungen dieser chemischen Mittel gegenuberstehen. Eine Integration und Auswertung dieser Erfahrungen und Kenntnisse ist dam dringend erforderlich.

Increased homoeologeous chromosome pairing in Hordeum vulgare × Triticum aestivum hybrids

Abstract: WHEAT and barley are the most important cereals in the agriculture of temperate zones. Although both genera belong to the same tribe, Triticeae, apparently successful crosses between wheat and barley have been reported recently1,2. I report here the production, morphology and cytology of F1 hybrids of Hordeum vulgare L. cv Betzes×Triticum aestivum L. cv Chinese Spring.

Spontaneous Listeric Encephalitis in Sheep Electron Microscopic Studies

Abstract: The brainstems of four sheep with spontaneous listeric encephalitis had scattered small foci of inflammatory cells (neutrophils or macrophages, or both) with scattered fragments of degenerating nerve fibers and glial cells. In extensive areas of malacia in the pons and medulla oblongata, there was loss of parenchyma with massive accumulation of macrophages, a few neutrophils, lymphocytes and plasma cells. In both types of lesions, phagocytes contained debris of myelin and axons, lipid vacuoles and occasionally bacteria. Neutrophils contained bacteria in phagocytic and digestive vacuoles. No bacteria were detected in macrophages but were detected in neurons and in one axon in tissue previously used for paraffin sections. A cardinal feature of listeric encephalitis in sheep is many nodules of macro- phages or neutrophils or both in the parenchyma of the brain stem, especially the pons and medulla oblongata. The proportion of macrophages to neutrophils in these inflammatory foci varies greatly in the same brain. Also, the predominant type of inflammatory cell (macrophage or neutrophil) varies between different brains (4). In light microscopic studies, bacteria occurred more frequently in neutrophils than macrophages (4). No reason was found for this apparent greater phagocytosis by neutrophils. Although the importance of cell mediated immunity in listeric infections is well established (16), there are no reports of the ultrastruc- tural features of the inflammatory response and phagocytosis of bacteria in listeric encephalitis. Experimental studies indicate that some proteins and viruses (herpes simplex virus, infectious bovine rhinotracheitis virus, pseudorabies virus, canine herpes virus) travel to the brain via axons of peripheral nerves (3, 5, 7-11, 17, 181. Viruses also may spread within the brain via neuronal processes (7). A recent study of listeric encephalitis in sheep suggested that bacteria migrated along peripheral nerves to the brain and that migration in the brain occurred, at least partly, along fiber tracts (4). A few neurons and neuronal processes contained organisms which suggested that neuronal cytoplasm is a vehicle for movement of the infectious agent

Factors affecting the pressure extraction of oil from flaxseed

Abstract: The effects of moisture content, age, growing location, and genotype of flaxseed on the efficiency of pressure extraction of oil, when extracted in a Carver press cylinder, were examined. Decreasing the seed moisture content from 7.8% to 2.3% increased the proportion of oil extracted from 31.4% to 49.6%, respectively. Oil was more difficult to extract as the age of the seed increased. The proportion of the total oil extracted varied from 25.0% to 41.4% depending upon the location where the seed was grown. The effect of genotype was less pronounced, ranging from a mean of 46.9% in Redwing to 54.2% in Redwood 65 for samples analyzed at normal storage moisture. Samples with high oil contents usually yielded the highest proportion of total oil recovered (r=0.893**, 9 df).

Mitochondrial Activity and Ethanol Accumulation in Ice-encased Winter Cereal Seedlings

Abstract: Cold-hardened dark-grown seedlings of winter wheat (Triticum aestivum L.) and winter rye (Secale cereale L.) are killed during total encasement in ice at −1 C at a rate related to the initial cold hardiness of the cultivars. Few plants remain alive after 7 days of encasement. Nonhardened seedlings are rapidly killed in ice. The respiratory properties of mitochondria isolated from plants after increasing periods of ice encasement decline slowly, and activity is little impaired when intact plants are about 50% killed. Electron microscopy indicates that mitochondrial structure is not disrupted until 3 weeks of ice encasement. Ethanol accumulates in hardened and nonhardened plants in ice, but at levels which are not toxic to the plants.

Review of the world species of prosapia fennah (rhynchota: homoptera: cercopidae)

Abstract: Characters of male genitalia and sternal coloration are used to supplement the variable characters of head shape and tegminal colour pattern in determining the species of the world Prosapia . Five new species are described: chiapana , hemelytra , ignifera , and isobar from Mexico, and fortior from Panama. One new combination is created: Prosapia miles (Fowler). Four subspecies are considered valid species: ignipectus (Fitch), inferens (Walker), ripalis Fennah (new status), and teapana Fennah (new status). P . simulons (Walker) (1858) is synonymized with fasciaticollis (Stal) (1864), and bicincta (Say) (1830) is synonymized with fraterna (Uhler) (1864). An illustrated key to males of the 14 world species is provided.

The black flies of iceland (diptera: simuliidae)

Abstract: Keys, descriptions, and illustrations are presented for the identification of the larvae, pupae, and adults of the four species of black flies known from Iceland, viz. Prosimulium (Prosimulium) ursinum, Simulium (Psilozia) vittatum, S. (Eusimulium) aureum, and S. (E.) vernum. Maps depicting their distributions within that country, and brief biological notes are given.

Resistance to the aphid-borne viruses in the potato

Abstract: Publisher Summary This chapter discusses the resistance to the aphid-borne viruses in potatoes. The potato is an ideal subject for study of resistance to disease. Breeding of potatoes is a slow process. Some cultivars with high resistance to certain viruses are possibly ahead of their time and may fail for some specific weakness or lack of overall suitability. Potato virologists have long been aware that while inoculation of young plants of susceptible cultivars will almost invariably result in infection of the tubers, inoculation of older plants is less likely to do so. There is recent evidence suggesting that the condition occurs during a specific, brief, time interval in the maturation of the plant. Mature-plant resistance can have special significance in combating aphid-borne viruses. Potato cultivars differ in their acceptability to aphids to the point where resistance to the vector has been suggested as a possible means of limiting virus spread. Plant resistance to the aphid per se does not seem to help in controlling the well known potato viruses. It appears that alfalfa mosaic virus might infect potatoes more frequently, given the appropriate vector migration.

Establishment and spread of tetrastichus julis (hymenoptera: eulophidae), a parasitoid of the cereal leaf beetle in ontario

Abstract: Tetrastichus julis (Walker), a European larval endoparasite of the cereal leaf beetle, Oulema melanopus (L), has become widely established in southern Ontario. In 1975, rates of parasitism in 14 counties varied from 15% in the east to 95% in the west Dispersal into Ontario was natural and is attributed to extensive colonization of the parasitoid in Michigan and other parts of the U.S. midwest. Reasons for its success in Ontario are suggested.

Laboratory assessment of the potential of 16 experimental compounds as soil insecticides

Abstract: The effectiveness of 16 experimental compounds as soil insecticides was assessed under laboratory conditions. Chlorpyrifos, carbofuran, and dieldrin were included as standard insecticides. Spectrum of activity as contact insecticides was determined using 24–48 h nymphs of the field cricket, Acheta pennsylvanicus (Burmeister), 24–48 h onion maggot adults, Hylemya antiqua (Meigen), third stage darksided cutworms, Euxoa messoria (Harris), northern corn rootworm adults, Diabrotica longicornis (Say), and honeybees, Apis mellifera L. First stage crickets were used to assess the biological activity of experimental compounds relative to soil type, moisture, and temperature and also their volatility in moist sand and persistence of biological activity over a 48 week period. All of the insecticides showed broad spectrum contact activity. Twelve showed fair to very good potential in soil. Four insecticides, Shell WL 24794 (O,O-dimethyl-S-1-[3-(5-methyl-1,2,4-oxadiazolyl)] ethyl phosphorodithioate), Shell WL 25735 (O-[2-chloro-1-(2,5-dichlorophenyl) vinyl] O-methyl methylphosphonothioate), Shell WL 26738 (O-[1-(2,4-dichlorophenyl) vinyl] O-methyl ethylphosphonothioate), and chlorpyrifos-methyl showed good potential. Two others, Counter® (S-[(tert-butylthio) methyl] O,O-diethyl phosphorodithioate) and Shell WL 24073 (O-[2-chloro-1-(2,5-dichlorophenyl) vinyl] O-methyl ethylphosphonothioate) were considered to have very good potential as soil insecticides.

A study of some north american larvae of the genus tetralopha zeller (lepidoptera: pyralidae: epipaschiinae)

Abstract: The larvae of Tetralopha web leaves of many kinds of trees and shrubs. A key to nine North American species is included, with descriptions of the last instar larvae. The species considered are Tetralopha robustella Zeller, T. militella Zeller, T. expandens Walker, T. aplastella Hulst, T. asperatella Clemens, T. vacciniivora Munroe, T. euphemella Hulst, T. scortealis Lederer, and T. baptisiella Fernald.

A new genus of ecitophilous diapriid wasps from arizona (hymenoptera: proctotrupoidea: diapriidae)

Abstract: Ecitovagus gibbus, new genus and new species of diapriid wasps (Diapriinae, Diapriini) associated with the army ant Neivamyrmex nigrescens (Cresson) in Arizona, is described. Taxonomic and ecological relationships with other ecitophilous diapriids are discussed.

Breeding for improvement of flowering attributes of winterhardy Rosa rugosa hybrids

Abstract: The purpose of this study was to determine at what stage of seedling development the flowering attributes in winterhardy R. rugosa hybrids could be assessed and if these attributes could be improved through breeding. The analysis of flowering was based on the duration of the flowering period and on amount of flowers produced.

Two new species of trisetacus (prostigmata: eriophyoidea) associated with cupressaceae

Abstract: Adults of Trisetacus chamaecypari n. sp., and female adults of T . thujivagrans n. sp. are described, and species of Trisetacus associated with Cupressaceae and Taxodiaceae are discussed and keyed. An original diagnosis of the genus Trisetacus is included.

Breeding for improvement of flowering attributes of winterhardy rosa kordesiiWulff hybrids

Abstract: The results from tetraploid hybrids of R. kordesii showed that flowering attributes can be improved by a suitable combination of modifying factors as was shown previously by investigations with diploid hybrids from R. rugosa. A longer flowering period than 7 weeks indicated always the ability for recurrent bloom in these investigations but a shorter flowering period did not always indicate non-recurrent bloom.

Influence of physical treatments on acetylene reduction (nitrogen fixation) in soils 1

Abstract: The effect of physical treatments such as drying, freezing, and heating on acetylene (C2H2) reduction (nitrogen fixation) in 3 types of soils was measured. Most treatments significantly affected ethylene (C2H4) production in the sandy loam. None of the treatments suppressed C2H4 formation in the sandy clay loam before 2 days. Muck soil with treatments of air‐drying, freeze‐drying, and freezing did not show different patterns in C2H4 production. However, auto claving and oven‐drying resulted in a pronounced increase in formation of C2H4. With exception of the heat treatments, no significant decreases in numbers of non‐symbiotic nitrogen‐fixers in soils were observed.

Halocyphina, A Marine Basidiomycete (Aphyllophorales)

Abstract: SUMMARYThe type species, Halocyphina villosa, is redescribed. It has a cyphellaceous habit, external hairs with walls soluble in 10% KOH, context hyphae with rare clamp connections, basidia and asy...