Alan Richardson

Bio: Alan Richardson is an academic researcher from Commonwealth Scientific and Industrial Research Organisation. The author has contributed to research in topics: Phytase & Soil water. The author has an hindex of 76, co-authored 363 publications receiving 19893 citations. Previous affiliations of Alan Richardson include Medical Research Council & Australian National University.

Acquisition of phosphorus and nitrogen in the rhizosphere and plant growth promotion by microorganisms

Abstract: The rhizosphere is a complex environment where roots interact with physical, chemical and biological properties of soil. Structural and functional characteristics of roots contribute to rhizosphere processes and both have significant influence on the capacity of roots to acquire nutrients. Roots also interact extensively with soil microorganisms which further impact on plant nutrition either directly, by influencing nutrient availability and uptake, or indirectly through plant (root) growth promotion. In this paper, features of the rhizosphere that are important for nutrient acquisition from soil are reviewed, with specific emphasis on the characteristics of roots that influence the availability and uptake of phosphorus and nitrogen. The interaction of roots with soil microorganisms, in particular with mycorrhizal fungi and non-symbiotic plant growth promoting rhizobacteria, is also considered in relation to nutrient availability and through the mechanisms that are associated with plant growth promotion.

Soil Microorganisms Mediating Phosphorus Availability Update on Microbial Phosphorus

Abstract: Microorganisms are integral to the soil phosphorus (P) cycle and as such play an important role in mediating the availability of P to plants. Understanding the microbial contribution to plant P nutrition and opportunities for manipulating specific microorganisms to enhance P availability in soil has

Prospects for using soil microorganisms to improve the acquisition of phosphorus by plants

Abstract: Microorganisms play an important role in the acquisition and transfer of nutrients in soil. For phosphorus (P), soil microorganisms are involved in a range of processes that affect P transformation and thus influence the subsequent availability of P (as phosphate) to plant roots. In particular, microorganisms can solubilize and mineralize P from inorganic and organic pools of total soil P. In addition, microorganisms may effectively increase the surface area of roots. Also, the microbial biomass itself contains a large pool of immobilized P that potentially is available to plants. Given that most soils are deficient in plant-available P and that P fertilizer represents a significant cost for agricultural production throughout the world, there is interest in using soil microorganisms as inoculants to mobilize P from poorly available sources in soil. Although potential clearly exists for developing such inoculants, their widespread application remains limited by a poor understanding of microbial ecology and population dynamics in soil, and by inconsistent performance over a range of environments. Furthermore, promotion of growth of plants in soil, as a consequence of microbial inoculation, may not necessarily be associated with characteristics such as P solubilization, which are manifest under laboratory conditions.

Plant and microbial strategies to improve the phosphorus efficiency of agriculture

Abstract: Background Agricultural production is often limited by low phosphorus (P) availability. In developing countries, which have limited access to P fertiliser, there is a need to develop plants that are more efficient at low soil P. In fertilised and intensive systems, P-efficient plants are required to minimise inefficient use of P-inputs and to reduce potential for loss of P to the environment.

Network analysis reveals functional redundancy and keystone taxa amongst bacterial and fungal communities during organic matter decomposition in an arable soil

Abstract: Organic matter (OM) decomposition and breakdown of crop residues are directly linked to carbon (C) sequestration in agricultural soils as a portion of the decomposed C becomes assimilated into stable microbial biomass. Microbial decomposition of OM may vary with quality of OM, addition of nutrients and functional types of microbes. While the role of fungi and bacteria in OM decomposition has received considerable attention, the succession and co-occurrence patterns of these communities during decomposition remain unexplored. Using 454 pyrosequencing and network analysis of bacterial 16S rRNA and fungal ITS genes in a time-course microcosm experiment, this study shows a positive effect of nutrient addition on overall microbial biomass and abundance of bacteria and fungi. Abundance of different bacterial and fungal groups changed up to 300-folds under straw- and nutrient amended treatments while the rate of decomposition remained similar, indicating a possible functional redundancy. Moreover, addition of nutrients significantly altered the co-occurrence patterns of fungal and bacterial communities, and these patterns were resource-driven and not phylogeny-driven. Richness, evenness and diversity decreased and were negatively associated with decomposition rate. Acidobacteria , Frateuria and Gemmatimonas in bacteria and Chaetomium , Cephalotheca and Fusarium in fungi were found as the keystone taxa. These taxa showed strong positive associations with decomposition, indicating their importance in C turnover. Overall, we show that addition of nutrients reduces diversity but favours the keystone taxa, and thereby increases microbial biomass.

Human biochemical genetics

Abstract: So far in this course we have dealt entirely with the evolution of characters that are controlled by simple Mendelian inheritance at a single locus. There are notes on the course website about gametic disequilibrium and how allele frequencies change at two loci simultaneously, but we didn’t discuss them. In every example we’ve considered we’ve imagined that we could understand something about evolution by examining the evolution of a single gene. That’s the domain of classical population genetics. For the next few weeks we’re going to be exploring a field that’s actually older than classical population genetics, although the approach we’ll be taking to it involves the use of population genetic machinery. If you know a little about the history of evolutionary biology, you may know that after the rediscovery of Mendel’s work in 1900 there was a heated debate between the “biometricians” (e.g., Galton and Pearson) and the “Mendelians” (e.g., de Vries, Correns, Bateson, and Morgan). Biometricians asserted that the really important variation in evolution didn’t follow Mendelian rules. Height, weight, skin color, and similar traits seemed to

Inositol trisphosphate and calcium signalling

Abstract: Inositol trisphosphate is a second messenger that controls many cellular processes by generating internal calcium signals. It operates through receptors whose molecular and physiological properties closely resemble the calcium-mobilizing ryanodine receptors of muscle. This family of intracellular calcium channels displays the regenerative process of calcium-induced calcium release responsible for the complex spatiotemporal patterns of calcium waves and oscillations. Such a dynamic signalling pathway controls many cellular processes, including fertilization, cell growth, transformation, secretion, smooth muscle contraction, sensory perception and neuronal signalling.

Building a Practically Useful Theory of Goal Setting and Task Motivation

Abstract: University of TorontoThe authors summarize 35 years of empirical research ongoal-setting theory. They describe the core findings of thetheory, the mechanisms by which goals operate, modera-tors of goal effects, the relation of goals and satisfaction,and the role of goals as mediators of incentives. Theexternal validity and practical significance of goal-settingtheory are explained, and new directions in goal-settingresearch are discussed. The relationships of goal setting toother theories are described as are the theory’s limitations.

Building a practically useful theory of goal setting and task motivation. A 35-year odyssey.

Abstract: The authors summarize 35 years of empirical research on goal-setting theory. They describe the core findings of the theory, the mechanisms by which goals operate, moderators of goal effects, the relation of goals and satisfaction, and the role of goals as mediators of incentives. The external validity and practical significance of goal-setting theory are explained, and new directions in goal-setting research are discussed. The relationships of goal setting to other theories are described as are the theory's limitations.