Showing papers by "Agriculture and Agri-Food Canada published in 1991"
TL;DR: Ninhydrin-reactive N extracted after a 1-day fumigation with CHC13 was compared to the C and N released by the fumigate-incubation method (FIM) in 37 soil samples collected from three tillage systems, and pastures in Atlantic Canada.
Abstract: Ninhydrin-reactive N extracted after a 1-day fumigation with CHC13 was compared to the C and N released by the fumigation-incubation method (FIM) in 37 soil samples (0-5 cm depth) collected from three tillage systems, and pastures in Atlantic Canada. The soils were slightly acidic, fine sandy loam Podzols with a relatively wide range of organic C and low clay content. Biomass C and the mineral N flush obtained using the FIM were closely related (r = 0.98) in all soils. Ninhydrin-reactive N was positively correlated with both biomass C (r = 0.88) and the mineral N flush (r = 0.92). Measurements of ninhydrin-reactive N released in the fumigation-extraction method provided a rapid assay for estimating microbial biomass C and N. and a comparison of microbial N content between different soils in field studies. For the tillage systems, where ninhydrin-reactive N ranged from 2 to 20μ N g− soil, multiplying the extracted ninhydrin-reactive N by 24 and 2.8 provided an estimate of microbial biomass C and the mineral N flush, respectively.
67 citations
TL;DR: Both antifeedant and insect growth regulatory activities of various samples of neem seed oil are shown to be correlated to azadirachtin concentrations in the oils, indicating that the neem insecticide provides pest control as effective as or better than pyrethrum, the current botanical insecticide of choice for organic growers.
Abstract: Leaves of the neem tree, Azadirachta indica A. Juss. (Meliaceae), have been used for centuries in India to protect stored grain from insect attack. Recent concern for the effects of synthetic insecticides on the environment and human health has provided the impetus for a reappraisal of the utility of neem derivatives as botanical crop protectants. Neem and its active principle, the limonoid azadirachtin, have several properties that are highly desirable for a natural insecticide. Azadirachtin is the most potent natural insect antifeedant discovered to date, suppressing insect feeding at concentrations of less than 1 part per million. Azadirachtin is also a potent insect growth regulator, which acts by disrupting molting and development, and interfering with reproduction in adult insects. These actions have been observed in over 90% of the more than 200 species of pest insects tested to date. Neem also has systemic action in some plants which could prove extremely valuable against stem- and root-feeding pests that are difficult to control. Finally, neem is essentially non-toxic to vertebrates, and in fact has a long history of medicinal use in southeast Asia.In the present paper we review our research aimed at developing a neem-based insecticide for use against pests of Canadian agriculture. We document the potent antifeedant action of azadirachtin in laboratory bioassays against the European corn borer, Ostrinia nubilalis Hubner, and the variegated cutworm, Peridroma saucia Hubner, and the molt-disrupting action of the compound in the migratory grasshopper, Melanoplus sanguinipes Fab., and the large milkweed bug, Oncopeltus fasciatus Dallas. Both antifeedant and insect growth regulatory activities of various samples of neem seed oil are shown to be correlated to azadirachtin concentrations in the oils. Field trials of an experimental neem insecticide conducted against pests of crucifers, corn, and potato in British Columbia, Ontario, and Prince Edward Island, respectively, indicate that the neem insecticide provides pest control as effective as or better than pyrethrum, the current botanical insecticide of choice for organic growers. The commercial prospectus for neem insecticides in Canada is discussed in light of our results.
44 citations
TL;DR: Shallow tillage (rotary harrow, disc harrow) was conducted to the 10 cm soil depth and compared with mouldboard ploughing (20 cm) and direct-drilling as mentioned in this paper.
Abstract: Changes in the soil condition were determined over a 4-year period, to assess the use of shallow tillage for the low-input production of spring cereals in Prince Edward Island. The soil was a Charlottetown fine sandy loam (Orthic Podzol) which has a low resistance to compaction. Shallow tillage (rotary harrow, disc harrow) was conducted to the 10 cm soil depth and compared with mouldboard ploughing (20 cm) and direct-drilling. Shallow tillage caused excessive compaction in the middle portion of the Ap horizon (8–16 cm) as characterized by reduced macroporosity ( 85%). Penetrometer resistance measurements indicated that both shallow tillage and direct-drilling reduced the depth of loose soil (
35 citations
TL;DR: Shallow tillage was assessed over a 4-year period for low-input production of spring cereals in Prince Edward Island as discussed by the authors, where the soil was a Charlottetown fine sandy loam, an Orthic Podzol, which is marginally suitable for direct drilling.
Abstract: Shallow tillage was assessed over a 4-year period for low-input production of spring cereals in Prince Edward Island. The soil was a Charlottetown fine sandy loam, an Orthic Podzol, which is marginally suitable for direct drilling. The tillage systems consisted of mouldboard ploughing, shallow tillage (rotary harrow, disc harrow) to the 10 cm soil depth, and direct-drilling. Plant populations were similar between tillage systems. Shallow tillage and direct-drilling produced similar grain yields as mouldboard ploughing when environmental conditions were optimum, but wet or very dry growing seasons favoured mouldboard ploughing and direct-drilling, respectively. Rotary harrowing prevented reduced plant growth rates prior to tillering and subsequently reduced accumulation of N in the plant and grain, associated with direct-drilling. Generally, the ability of plants to utilize N for growth was considered to be the main factor influencing N yield differences between tillage systems. In comparison to mouldboard ploughing, shallow tillage reduced machinery costs and energy requirements by 25–48% for seedbed production. In addition, shallow tillage had the advantage of timeliness and increased the potential area which could be prepared for seeding during the limited early spring period. Overall, shallow tillage removed some of the constraints associated with direct-drilling and provides an alternative, in rotational farming systems on fine sandy loams, to mouldboard ploughing.
34 citations
TL;DR: It is suggested that the overproduction of digestive proteolytic enzymes may have been a contributory factor in protein attrition, resulting in slower growth and reduced reproduction in adult male grasshoppers.
18 citations
TL;DR: A total of 436 embryos/unfertilized ova was collected from 30 foot-and-mouth disease (FMD) viremic cattle; 106 of these embryos/ova were from eight donors that had FMD virus in their reproductive tracts.
15 citations
15 citations
TL;DR: In this paper, residues of di-(2-ethylhexyl)phthalate (DEHP) were extracted along with deoxynivalenol (DON) from plastic bags containing corn contaminated by Fusarium graminearum.
Abstract: Residues of di-(2-ethylhexyl)phthalate (DEHP) were extracted along with deoxynivalenol (DON) from plastic bags containing corn contaminated byFusarium graminearum. The concentration/extraction of this residue involved a series of silica gel-400 chromatography columns followed by purification by semi-preparative column chromatography, using hexane/dichloromethane as the mobile phase. The purified product was identified by NMR (1H and13C) and mass spectrometry. Quantification of DEHP was also done by high performance liquid chromatography (HPLC).
10 citations
TL;DR: An analytical method for the analysis of glyphosate and its metabolite (aminomethyl)phosphonic acid (AMPA) in lentil samples was presented in this paper, where they were extracted from powdered samples with water and chloroform.
Abstract: An analytical method is presented for the analysis of glyphosate and its metabolite (aminomethyl)phosphonic acid (AMPA), in lentil samples. They were extracted from powdered samples with water and chloroform. The aqueous layer was acidified and passed through a cation exchange column. The eluate was made basic, passed through an anion exchange column in the hydroxide form and discarded. The latter column was eluted with hydrochloric acid (0.3 M) which was collected, evaporated under vacuum to 1 ml, diluted with water to 10 ml, filtered and analysed for glyphosate and metabolite using a liquid chromatograph with a post-column reactor and a fluorescence detector. The limit of detection, average recovery and coefficient of variation (CV) were 0.08 μg g−1, 92.5% and 7.3% for glyphosate and 0.1 μg g−1, 92.5% and 8.3% for AMP A. The detector response was found to be linear within the range 20–400 ng.
9 citations
TL;DR: Findings indicated that droplet trajectories were the most important factor influencing deposits on wheat heads, especially those positioned directly below nozzles.
5 citations
TL;DR: Semen acidification had no apparent effect on the post-thaw percentage of intact acrosomes and the fertilization rate was 88%, and 78% of the embryos were of transferable quality.
TL;DR: Niska is a white-skinned, white-fleshed potato cultivar with a maincrop maturity, stable yield and chipping quality and good storage characteristics.
Abstract: Niska is a white-skinned, white-fleshed potato cultivar with a maincrop maturity, stable yield and chipping quality and good storage characteristics. It has considerable resistance to Common scab, Early blight, PLRV, PVY and PVS. Evaluation conducted by chip processors in Alberta and Ontario, under commercial conditions, indicates that the cultivar has good storage characteristics.