Nicolas Tremblay

Bio: Nicolas Tremblay is an academic researcher from Agriculture and Agri-Food Canada. The author has contributed to research in topics: Chlorophyll & Fertilizer. The author has an hindex of 37, co-authored 125 publications receiving 5572 citations. Previous affiliations of Nicolas Tremblay include Laval University.

Strategies to Make Use of Plant Sensors-Based Diagnostic Information for Nitrogen Recommendations

Abstract: Improvements of nitrogen use efficiency (NUE) may be achieved through the use of sensing tools for N status determination Leaf and canopy chlorophyll, as well as leaf polyphenolics concentrations, are characteristics strongly affected by N availability that are often used as a surrogate to direct plant N status estimation Approaches with near-term operational sensors, handheld and tractor-mounted, for proximal remote measurements are considered in this review However, the information provided by these tools is unfortunately biased by factors other than N To overcome this obstacle, normalization procedures such as the well-fertilized reference plot, the no-N reference plot, and relative yield are often used Methods to establish useful relationships between sensor readings and optimal N rates, such as critical NSI (nitrogen sufficiency index), INSEY (in-season estimated yield), and the relationship between chlorophyll meter readings, grain yield, and sensor-determined CI (chlorophyll index) are also reviewed In a few cases, algorithms for translating readings into actual N fertilizer recommendation have been developed, but their value still seems limited to conditions similar to the ones where the research was conducted Near-term operational sensing can benefit from improvements in sensor operational characteristics (size and shape of footprint, positioning) or the choice of light wavebands more suitable for specific conditions (ie, genotype, growth stage, or crop density) However, one important limitation to their widespread use is the availability of algorithms that would be reliable in a variety of soil and weather conditions

Ultraviolet-induced fluorescence for plant monitoring: present state and prospects

Abstract: [FR] Fluorescence induite par le rayonnement ultraviolet pour le suivi de la vegetation : etat actuel et perspectives. L'excitation de feuilles vertes dans l'ultraviolet induit deux types de fluorescence distinctes, fondamentalement differentes, mais complementaires : la fluorescence bleu-verte dans la region 400-630 nm et la fluorescence chlorophyllienne dans la partie rouge-infra-rouge du spectre. Les intensites relatives de ces deux types de fluorescence sont tres sensibles aux proprietes intrinseques des feuilles et aux facteurs de l'environnement. Par consequent, les spectres d'emission de fluorescence induite par le rayonnement ultraviolet peuvent etre consideres comme des signatures complexes qui renseignent sur l'etat physiologique de la plante. La fluorescence des feuille induite par l'UV nous informe sur la photosynthese, les reactions primaires photochimiques et la teneur en chlorophylle, et aussi sur l'accumulation des produits du metabolisme secondaire ainsi que sur l'etat redox de la cellule. Dans cet article, nous nous sommes particulierement interesses a l'application de ces signaux a la teledetection active de la vegetation, le « fluorosensing ».

Remote Estimation of Crop Chlorophyll Content Using Spectral Indices Derived From Hyperspectral Data

Abstract: This paper examines the use of simulated and measured canopy reflectance for chlorophyll estimation over crop canopies. Field spectral measurements were collected over corn and wheat canopies in different intensive field campaigns organized during the growing seasons of 2004 and 2005. They were used to test and evaluate several combined indices for chlorophyll determination using hyperspectral imagery (Compact Airborne Spectrographic Imager). Several index combinations were investigated using both PROSPECT-SAILH canopy simulated spectra and field-measured reflectances. The relationships between leaf chlorophyll content and combined optical indices have shown similar trends for both PROSPECT-SAILH simulated data and ground-measured data sets, which indicates that both spectral measurements and radiative transfer models hold comparable potential for the quantitative retrieval of crop foliar pigments. The data set used has shown that crop type had a clear influence on the establishment of predictive equations as well as on their validation. In addition to generating different predictive equations, corn and wheat data yielded contrasting agreement between estimated and measured chlorophyll contents even for the same predictive algorithm. Among the set of indices tested in this paper, index combinations like modified chlorophyll absorption ratio index/optimized soil-adjusted vegetation index (OSAVI), triangular chlorophyll index/OSAVI, moderate resolution imaging spectrometer terrestrial chlorophyll index/improved soil-adjusted vegetation index (MSAVI), and red-edge model/MSAVI seem to be relatively consistent and more stable as estimators of crop chlorophyll content.

The Design and Analysis of Experiments

Abstract: THE DESIGN AND ANALYSIS OF EXPERIMENTS. By Oscar Kempthorne. New York, John Wiley and Sons, Inc., 1952. 631 pp. $8.50. This book by a teacher of statistics (as well as a consultant for \"experimenters\") is a comprehensive study of the philosophical background for the statistical design of experiment. It is necessary to have some facility with algebraic notation and manipulation to be able to use the volume intelligently. The problems are presented from the theoretical point of view, without such practical examples as would be helpful for those not acquainted with mathematics. The mathematical justification for the techniques is given. As a somewhat advanced treatment of the design and analysis of experiments, this volume will be interesting and helpful for many who approach statistics theoretically as well as practically. With emphasis on the \"why,\" and with description given broadly, the author relates the subject matter to the general theory of statistics and to the general problem of experimental inference. MARGARET J. ROBERTSON

Climate Change 2007: The Physical Science Basis.

Abstract: Cause, conseguenze e strategie di mitigazione Proponiamo il primo di una serie di articoli in cui affronteremo l’attuale problema dei mutamenti climatici. Presentiamo il documento redatto, votato e pubblicato dall’Ipcc - Comitato intergovernativo sui cambiamenti climatici - che illustra la sintesi delle ricerche svolte su questo tema rilevante.