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.

Long-term phosphorus fertilization impacts soil fungal and bacterial diversity but not AM fungal community in alfalfa.

Abstract: Soil function may be affected by cropping practices impacting the soil microbial community. The effect of different phosphorus (P) fertilization rates (0, 20, or 40 kg P2O5 ha−1) on soil microbial diversity was studied in 8-year-old alfalfa monocultures. The hypothesis that P fertilization modifies soil microbial community was tested using denaturing gradient gel electrophoresis and phospholipids fatty acid (PLFA) profiling to describe soil bacteria, fungi, and arbuscular mycorrhizal (AM) fungi diversity. Soil parameters related to fertility (soil phosphate flux, soluble P, moisture, phosphatase and dehydrogenase assays, and carbon and nitrogen content of the light fraction of soil organic matter) were also monitored and related to soil microbial ribotype profiles. Change in soil P fertility with the application of fertilizer had no effect on crop yield in 8 years, but on the year of this study was associated with shifts in the composition of fungal and bacterial communities without affecting their richness, as evidenced by the absence of effect on the average number of ribotypes detected. However, variation in soil P level created by a history of differential fertilization did not significantly influence AM fungi ribotype assemblages nor AM fungi biomass measured with the PLFA 16:1ω5. Fertilization increased P flux and soil soluble P level but reduced soil moisture and soil microbial activity, as revealed by dehydrogenase assay. Results suggest that soil P fertility management could influence soil processes involving soil microorganisms. Seasonal variations were also recorded in microbial activity, soil soluble P level as well as in the abundance of specific bacterial and fungal PLFA indicators of soil microbial biomass.

Research on biology and control of Sclerotinia diseases in Canada1

Abstract: Sclerotinia sclerotiorum (Lib.) de Bary and Sclerotinia minor Jagger are two of the species in the genus Sclerotinia found in Canada. While S. sclerotiorum is distributed country-wide and causes disease on numerous economically important crops including oilseeds, pulses, forage legumes, vegetables, and ornamentals, S. minor has only been reported on lettuce in Quebec and Ontario. During the past five decades, Canadian researchers have made a substantial contribution to the understanding of the biology and control of S. sclerotiorum and, to a lesser extent, of S. minor. This review summarizes the progress of Canadian research on Sclerotinia diseases in the past 50 years, with specific emphasis in the areas such as strain differentiation, epidemiology, new types of sclerotia, survival and germination of sclerotia, and biocontrol. Le Sclerotinia sclerotiorum (Lib.) de Bary et le Sclerotinia minor Jagger sont deux especes du genre Sclerotinia trouvees au Canada. Alors que le S. sclerotiorum a une distribution...

Plant hybrid zones affect biodiversity: tools for a genetic‐based understanding of community structure

Abstract: Plant hybrid zones are dynamic centers of ecological and evolutionary processes for plants and their associated communities. Studies in the wild and in gardens with synthetic crosses showed that hybrid eucalypts supported the greatest species richness and abundances of insect and fungal taxa. In an updated review of 152 case studies of taxa associated with diverse hybridizing systems, there were 43 (28%) cases of hybrids being more susceptible than their parent species, 7 (5%) resistant, 35 (23%) additive, 35 (23%) dominant, and 32 (21%) showed no response to hybridization. Thus, most taxa respond to hybrids in ways that result in equal or greater abundance, and hybrids tend to accumulate the taxa of their parent species. These studies suggest that genetic-based plant traits affect the distribution of many species and that the variation in hybrids can be used as tools to examine the genetic components of community structure and biodiversity. Several patterns have emerged thus far. (1) Genetic variation between classes of hybrids (e.g., F1’s vs. backcrosses) may equal or even exceed that found between species. (2) As a reflection of this genetic variation, herbivores are more likely to differentiate between hybrid classes than they are to differentiate between pure plant species. (3) The communities associated with different hybrid classes can differ from one another as well as from their parental species. (4) Generalist and specialist herbivores predictably vary in their responses to hybrids. (5) Plant hybrid zones may represent essential habitat for some arthropod species. (6) Even nesting birds respond to hybridizing plants. (7) Including multiple trophic levels and taxa from microbes to vertebrates, susceptible hybrid genotypes support greater biodiversity than resistant genotypes. (8) The effects of hybridization on common or keystone species can either positively or negatively affect biodiversity. The indirect impacts of hybridization on biodiversity may exceed the direct impacts and may result in “apparent” herbivore resistance or susceptibility at the community level. (9) Although hybrids are often maligned, exotic or problem hybrids generally result from human disturbances, whereas native hybrids are part of natural ecosystems and should be conserved. Three predictions are made: (1) Intermediate genetic differences between the parental species will result in the greatest genetic variation in the hybrid zone, which in turn will have a positive effect on biodiversity. (2) Bidirectional introgression enhances species richness on hybrids, whereas F1 sterility and unidirectional introgression limit the accumulation of species on hybrids. (3) Although susceptible hybrids are likely to support the greatest biodiversity, the impacts of hybridization on keystone species will be crucial in determining the overall effect.