Donald Picard

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In order to study the nutrient and water uptake of rootsin situ, we need a quantitative three-dimensional dynamic model of the root system architecture. The present model takes into account current observations on the morphogenesis of the maize root system. It describes the root system as a set of root axes, characterised by their orders and their(More)
A simple three-compartment model was used to evaluate the supply of organic matter to the soil by the decay of the dead roots of an intensively managedPanicum maximum sward. The only known data were the weights of the total dry matter of the roots measured every two weeks for a whole year. By means of three simplifying hypotheses it was possible to evaluate(More)
The oxidation of a carbon anode with air and CO2 occurs during the electrolysis of alumina in Hall-Héroult cells, resulting in a significant overconsumption of carbon and dusting. Boron is well known to decrease the rate of this reaction for graphite. In this work, the application of boron oxide has been investigated to evaluate its inhibition effect on the(More)
High quality baked carbon anodes contribute to the optimal performance of aluminum reduction cells. However, the currently decreasing quality and increasing variability of anode raw materials (coke and pitch) make it challenging to manufacture the anodes with consistent overall quality. Intercepting faulty anodes (e.g., presence of cracks and pores) before(More)
Many species are migratory, resulting in a life cycle divided into periodic stages occurring in different habitats occupied for a limited amount of time. Estimating the time spent in each habitat is crucial to understanding how individuals modulate their activities and thus to evolutionary ecology and conservation biology. Several methods, including some(More)
The transpiration of a rice plant, variety IRAT 13, grown in a controlled environment, was investigated by means of a continuous record of the difference between the rate of water vapour in the air admitted in the growth cabinet and that in the air issued from it. The plant was submitted to water stress by stopping the irrigation to the soil in which the(More)
Le cycle nycthéméral de transpiration de la variété IRAT 13 de riz pluvial, cultivée en conditions contrôlées, présente une particularité pour une plante en C3:dans une période 12 h de jour-12 h de huit, la transpiration nocturne passe par un miniumum 1h30 après l'extinction puis réaugmente pour atteindre, avant l'éclairement, 1,8 fois la valeur du minimum.(More)
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