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Leuven, Belgium

Landschoot S.,University College Ghent | Landschoot S.,Ghent University | Waegeman W.,Ghent University | Audenaert K.,University College Ghent | And 6 more authors.
Computers and Electronics in Agriculture | Year: 2013

Fusarium head blight is a worldwide problem in wheat growing areas. In addition to yield loss, Fusarium species can also synthesise mycotoxins and thus threaten animal and human health. Models for predicting Fusarium head blight and deoxynivalenol content in wheat provide farmers with a tool for preventing yield loss and mycotoxin contamination. Growers may use the predictions to underpin decision making on cultivation techniques and the application of fungicides. At the end of the growing season, the food and feed industry may use the predictions to make marketing decisions. Furthermore, the predictions are helpful to identify regions with a higher disease pressure and thus improve sampling efficiency. Based on the data of 3100 wheat samples from 18 locations throughout Belgium between 2002 and 2011, various predictive models were evaluated. The most accurate models were implemented in a web tool to provide growers with field-specific predictions of Fusarium head blight incidence and deoxynivalenol content. The predictions are based on the agronomic variables of a specific wheat field and weather data from the nearest weather station. During the growing season several predictions can be asked. The web tool provides a graphical representation of the predicted results together with an advice on management strategies and recommendations for fungicide application. © 2013 Elsevier B.V. Source

Vranckx G.,Catholic University of Leuven | Jacquemyn H.,Catholic University of Leuven | Mergeay J.,Research Institute for Nature and Forest INBO | Cox K.,Research Institute for Nature and Forest INBO | And 4 more authors.
Annals of Botany | Year: 2014

Background and Aims The interaction between forest fragmentation and predicted climate change may pose a serious threat to tree populations. In small and spatially isolated forest fragments, increased homozygosity may directly affect individual tree fitness through the expression of deleterious alleles. Climate change-induced drought stress may exacerbate these detrimental genetic consequences of forest fragmentation, as the fitness response to low levels of individual heterozygosity is generally thought to be stronger under environmental stress than under optimal conditions. Methods To test this hypothesis, a greenhouse experiment was performed in which various transpiration and growth traits of 6-month-old seedlings of Quercus robur differing in multilocus heterozygosity (MLH) were recorded for 3 months under a well-watered and a drought stress treatment. Heterozygosity-fitness correlations (HFC) were examined by correlating the recorded traits of individual seedlings to their MLH and by studying their response to drought stress. Key Results Weak, but significant, effects of MLH on several fitness traits were obtained, which were stronger for transpiration variables than for the recorded growth traits. High atmospheric stress (measured as vapour pressure deficit) influenced the strength of the HFCs of the transpiration variables, whereas only a limited effect of the irrigation treatment on the HFCs was observed. Conclusions Under ongoing climate change, increased atmospheric stress in the future may strengthen the negative fitness responses of trees to low MLH. This indicates the necessity to maximize individual multilocus heterozygosity in forest tree breeding programmes. © 2014 The Author. Source

van Beek J.,Catholic University of Leuven | Tits L.,Catholic University of Leuven | Somers B.,Catholic University of Leuven | Deckers T.,PCFruit Research Station | And 2 more authors.
International Journal of Applied Earth Observation and Geoinformation | Year: 2015

Satellite remote sensing provides an alternative to time-consuming and labor intensive in situ measurements of biophysical variables in agricultural crops required for precision agriculture applications. In orchards, however, the spatial resolution causes mixtures of canopies and background (i.e. soil, grass and shadow), hampering the estimation of these biophysical variables. Furthermore, variable background mixtures obstruct meaningful comparisons between different orchard blocks, rows or within each row. Current correction methodologies use spectral differences between canopies and background, but struggle with a vegetated orchard floor. This background influence and the lack of a generic solution areaddressed in this study. Firstly, the problem was demonstrated in a controlled environment for vegetation indices sensitive to chlorophyll content, water content and leaf area index. Afterwards, traditional background correction methods (i.e. soil-adjusted vegetation indices and signal unmixing) were compared to the proposed vegetation index correction. This correction was based on the mixing degree of each pixel (i.e. tree cover fraction) to rescale the vegetation indices accordingly and was applied to synthetic and WorldView-2 satellite imagery. Through the correction, the effect of background admixture for vegetation indices was reduced, and the estimation of biophysical variables was improved (δR2= 0.2-0.31). © 2014 Elsevier B.V. Source

Tits M.,Soil Service of Belgium | Elsen A.,Soil Service of Belgium | Bries J.,Soil Service of Belgium | Vandendriessche H.,Soil Service of Belgium | Vandendriessche H.,Catholic University of Leuven
Plant and Soil | Year: 2012

Aims: Substantial amounts of VFG-compost are produced annually in Flanders. Our objective was to analyse the effects of VFG-compost applications in a common crop rotation. Methods: Data from a long-term (1997 - present) field trial were analysed. Simulations with the RothC-model were performed to get a better insight into the dynamics of the underlying soil organic matter. Results: VFG-compost applications (15 t.ha -1 3-yearly up to 45 t.ha -1 yearly) can replace a substantial part of the mineral nitrogen fertilisation. Nitrogen recovery rates ranged from 6 to 22 %. Plots fertilised according to the nitrogen advice had comparable yields, whether this advice had been provided (partially) through VFG-compost or not. Long-term VFG applications resulted in carbon accumulation in the top soil. The RothC-model gave a good prediction of the carbon change with low to moderate VFG applications, but tended to overestimate the carbon change with high applications. The simulation results indicated that the carbon accumulation was mainly due to an increase of the more resistant carbon fractions. In the long term, compost applications increased the nitrogen supplying capacity of the soil, as illustrated by the gradual increase of the mineral nitrogen stocks in spring over the years. Conclusions: VFG-compost applications had a positive effect both on crop yields and soil organic matter. The RothC-model was used to simulate long-term effects, but its calibration should be improved for long-term compost applications. © 2012 Springer Science+Business Media B.V. Source

Janssens P.,Soil Service of Belgium | Deckers T.,PCFruit Research Station | Elsen F.,Soil Service of Belgium | Elsen A.,Soil Service of Belgium | And 3 more authors.
Agricultural Water Management | Year: 2011

The present study examines the need for irrigation in pear trees (Pyrus Communis, cv. 'Conference') under low evaporative demand conditions, like in Belgium, in order to maintain a consistent fruit yield and high fruit size. To determine the sensitivity of the pear yield under low evaporative demand conditions three different orchards were monitored. The study shows that a Ψsoil of -60kPa during shoot growth has no effect on fruit yield but lower Ψsoil values induced a decline in both fruit size and total yield. Just as for arid environments a Ψstem of -1.5MPa is related to negative yield responses. In dry conditions lower Ψsoil and Ψstem values were observed in root pruned trees compared to not root pruned trees in the same irrigation treatment, however without yield decline. In one orchard a biannual bearing tendency was observed after root pruning. Furthermore intensive Ψsoil measurements show a high variation in Ψsoil between orchards, and within an orchard. This underlines the need for irrigation management on a parcel level and the need for new irrigation scheduling techniques which take the spatial variation in the orchard into account. © 2011 Elsevier B.V. Source

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