Agriculture and Agri-Food Canada

About: Agriculture and Agri-Food Canada is a facility organization based out in Ottawa, Ontario, Canada. It is known for research contribution in the topics: Population & Soil water. The organization has 10921 authors who have published 21332 publications receiving 748193 citations. The organization is also known as: Department of Agriculture and Agri-Food.

Body size as an indicator of parasitoid quality in male and female Anagyrus kamali (Hymenoptera: Encyrtidae).

Abstract: The parasitoid Anagyrus kamali Moursi was recently introduced into the Caribbean as a biological control agent against the hibiscus mealybug, Maconellicoccus hirsutus Green. In the laboratory, parasitoid size, as measured by left hind tibia length, was positively correlated with several indicators of the parasitoid‘s fitness: longevity, mating preference, fecundity, reproductive longevity, progeny emergence and sex-ratio. When fed ad libidum with honey drops, large male parasitoids lived significantly longer (29.1 ± 6.5 days) than small ones (18.4 ± 5.7 days). Large females also lived significantly longer (35.4 ± 10 days) than small females (27.9 ± 9.6 days). Females showed no significant mating preference between large and small males. Lifetime fecundity was positively correlated with the size of adult females and ranged from 37 ± 21 eggs for small females to 96 ± 43 eggs for large ones. The reproductive longevity, daily oviposition rate, and number of progeny were also higher among large parasitoids. The sex ratio of progeny from small female parasitoids was higher (0.76 ± 0.24) than that of large individuals (0.47 ± 0.18).

Changes in the Rumen Epimural Bacterial Diversity of Beef Cattle as Affected by Diet and Induced Ruminal Acidosis

Abstract: Little is known about the nature of the rumen epithelial adherent (epimural) microbiome in cattle fed different diets. Using denaturing gradient gel electrophoresis (DGGE), quantitative real-time PCR (qPCR), and pyrosequencing of the V3 hypervariable coding region of 16S rRNA, epimural bacterial communities of 8 cattle were profiled during the transition from a forage to a high-concentrate diet, during acidosis, and after recovery. A total of 153,621 high-quality gene sequences were obtained, with populations exhibiting less taxonomic variability among individuals than across diets. The bacterial community composition exhibited clustering (P 1% of the rumen epimural population, differing (P ≤ 0.05) among diets. During acidosis, levels of Atopobium, Desulfocurvus, Fervidicola, Lactobacillus, and Olsenella increased, while during the recovery, Desulfocurvus, Lactobacillus, and Olsenella reverted to levels similar to those with the high-grain diet and Sharpea and Succinivibrio reverted to levels similar to those with the forage diet. The relative abundances of bacterial populations changed during diet transition for all qPCR targets except Streptococcus spp. Less than 5% of total operational taxonomic units (OTUs) identified exhibited significant variability across diets. Based on DGGE, the community structures of epithelial populations differed (P ≤ 0.10); segregation was most prominent for the mixed forage diet versus the grain, acidotic challenge, and recovery diets. Atopobium, cc142, Lactobacillus, Olsenella, RC39, Sharpea, Solobacterium, Succiniclasticum, and Syntrophococcus were particularly prevalent during acidosis. Determining the metabolic roles of these key genera in the rumens of cattle fed high-grain diets could define a clinical microbial profile associated with ruminal acidosis.

Soil test phosphorus and phosphorus fractions with long-term phosphorus addition and depletion

Abstract: The fate of fertilizer P in soil during crop production has to be determined to evaluate the long-term economic value and sustainability of fertilizer practices. We assessed changes in soil test P and soil P fractions with continuous P fertilization and soil P depletion under continuous corn (Zea mays L.) in a Ste. Rosalie clay soil (humic Gleysol; fine, mixed, frigid, Typic Humaquept). Soil samples were analyzed for Mehlich-3 P (M-3 P) and P fractions using a modified Hedley's procedure. Soil M-3 P values remained constant in spite of crop removal in soil not receiving fertilizer for 10 yr. Continuous P fertilization at rates from 44 to 132 P ha -1 yr -1 increased linearly soil M-3 P, with 6.3 kg P ha -1 of net P addition required to increase M-3 P by 1 mg P kg -1 . Residual fertilizer P in soil resulted from the continuous P addition were found predominately in labile inorganic P (LPj) (NaHCO 3 -P 1 ) and moderately labile P i (MLP,) (NaOH-P i ). Increased P rates favored soil P transformation from LP i to MLP i , indicating enhanced soil P retention. With P depletion, soil M-3 P declined in plots previously receiving 132 kg P ha -1 yr -1 , with 4.2 kg P ha -1 crop P removal decreasing soil M-3 P by 1 mg P kg -1 . Continuous crop removal of soil residual P (Res-P) resulted in decreases in soil LP i and increases in MLP i , an indication of increased retention of Res-P with time. However, moderately stable P i (HCl-P,) remained constant, both with continuous P addition and P depletion. Conversion of residual fertilizer P to less available P forms in soil was a slow process and thus the fate of the Res-P should be taken into consideration when developing soil nutrient management plans.

Gaseous nitrogen emissions and forage nitrogen uptake on soils fertilized with raw and treated swine manure.

Abstract: Treatments to reduce solids content in liquid manure have been developed, but little information is available on gaseous N emissions and plant N uptake after application of treated liquid swine manure (LSM). We measured crop yield, N uptake, and NH 3 and N 2 O losses after the application of mineral hertilizer (NH 4 NO 3 ), raw LSM, and LSM that was decanted, filtered, anaerobically digested, or chemically flocculated. The experiment was conducted from 2001 to 2003 on a loam and a sandyloam cropped to timothy (Phleum pratense L.) with annual applications equivalent to 80 kg N ha -1 in spring and 60 kg; N ha -1 after the first harvest. Raw LSM resulted in NH 3 emissions three to six times larger (P 50% compared with raw LSM (P 90% of that with mineral fertilizer. The LSM treatments tended to increase forage yield and N uptake relative to raw LSM. We conclude that treated or untreated LSM offers an alternative to mineral fertilizers for forage grass production but care must be taken to minimize NH 3 volatilization. Removing solids from LSM by mechanical, chemical, and biological means reduced NH 3 losses from LSM applied to perennial grass.

Ginsenosides in Roots and Leaves of American Ginseng

Abstract: The six major ginsenosides, Rg1, Re, Rb1, Rc, Rb2, and Rd, in roots and leaves of American ginseng have been isolated and quantified by high-performance liquid chromatography. In 4-year-old roots, the main ginsenosides were Re and Rb1, and together they accounted for >75% of the total ginsenosides. In leaves, the concentration and composition of ginsenosides varied with the maturity of the leaf tissue. One-month-old leaves contained 1.33−2.64 g ginsenoside/100 g dry weight, and the ginsenoside Re accounted for >50% of the total concentration. In mature, 4-month-old leaves, the total ginsenoside content ranged from 4.14 to 5.58 g/100 g dry weight, and the ginsenosides Re and Rd each accounted for ∼40% of the total ginsenosides. The production site of ginseng influenced the ginsenoside contents of roots and leaves. However, few significant correlations were found between root and leaf ginsenosides and between ginsenoside levels and mineral composition of the leaves and soil. Keywords: Panax quinquefolium; s...