Interannual variability of CO2 fluxes and yield by a winter wheat crop (Triticum aestivum L.)

In this study, two winter wheat (Triticum aestivum L.) cropping seasons were compared at the Lonzée (Belgium) experimental site. The site, crop management, sowing and harvest dates were similar on the two years. The main difference between the seasons was due to to climate conditions. Continuous eddy-covariance fluxes, leaf scale photosynthesis measurements and crop development monitoring were performed during the whole vegetation periods. Globally, the two years were characterised by a higher than normal air temperature (9.9 °C and 11.9 °C respectively against 9.4 °C for standard) and lower than normal rainfalls (595.1 mm and 675.1 mm respectively against 772 mm for standard). In addition, the second season (2006-2007) was characterised by an exceptionally mild winter, dry and hot conditions in April and by humid and cloudy conditions during the last vegetation phases. These particular conditions induced earlier growth stages and the comparison of global fluxes gives contrasting results: gross primary productivity (GPP) was larger in 2007 but, on the contrary, net primary productivity (NPP) and crop productivity were lower on this year. The bad yields could be explained, on one hand by the drought in April 2007 that induced abnormally small flag leaves, on the other hand by cloudy and humid conditions from end May to harvest, that induced an assimilation reduction due to low radiation and favoured disease development. The simultaneous higher GPP and lower NPP and productivity in 2006-2007 raise the question of carbon allocation. It suggests that the excess carbon assimilated in 2006-2007 was not stored in grain or straw and thus that it would have been stored in the roots or in vegetation parts that decompose before the harvest. Further biomass measurements (and especially root biomass) are necessary to confirm this hypothesis.Impact de la gestion culturale et du climat sur les flux de CO2, le développement et le rendement de grandes culture

Interannual variability of CO2 fluxes, growth and yield by a winter wheat crop (Triticum aestivum L.)

In this study, two winter wheat (Triticum aestivum L.) cropping seasons were compared at the Lonzée (Belgium) experimental site. The site, crop management, sowing and harvest dates were similar on the two years. The main difference between the seasons was due to to climate conditions. Continuous eddy-covariance fluxes, leaf scale photosynthesis measurements and crop development monitoring were performed during the whole vegetation periods. Globally, the two years were characterised by a higher than normal air temperature (9.9 °C and 11.9 °C respectively against 9.4 °C for standard) and lower than normal rainfalls (595.1 mm and 675.1 mm respectively against 772 mm for standard). In addition, the second season (2006-2007) was characterised by an exceptionally mild winter, dry and hot conditions in April and by humid and cloudy conditions during the last vegetation phases. These particular conditions induced earlier growth stages and the comparison of global fluxes gives contrasting results: gross primary productivity (GPP) was larger in 2007 but, on the contrary, net primary productivity (NPP) and crop productivity were lower on this year. The bad yields could be explained, on one hand by the drought in April 2007 that induced abnormally small flag leaves, on the other hand by cloudy and humid conditions from end May to harvest, that induced an assimilation reduction due to low radiation and favoured disease development. The simultaneous higher GPP and lower NPP and productivity in 2006-2007 raise the question of carbon allocation. It suggests that the excess carbon assimilated in 2006-2007 was not stored in grain or straw and thus that it would have been stored in the roots or in vegetation parts that decompose before the harvest. Further biomass measurements (and especially root biomass) are necessary to confirm this hypothesis.Impact de la gestion culturale et du climat sur les flux de CO2, le développement et le rendement de grandes culture

Impact of climatic conditions on a winter wheat (Triticum aestivum Sp.) crop : interannual variability of CO2 fluxes, plant growth and crop yield

This study analyses the interannual variability of carbon dioxide fluxes, growth and productivity of a winter wheat (Triticum aestivum L.) crop. Two growing seasons (2004-2005 and 2006-2007) were compared. Continuous eddy covariance fluxes, leaf scale photosynthesis measurements and crop development monitoring were performed during the two vegetation seasons until harvest at the Lonzée (Belgium) experimental site. The winter wheat was sown and harvested at similar dates (about mid-October and in early August); crop management by the farmer was similar and corresponded at standard. Globally, the two years were characterised by a higher than normal air temperature (9.9 °C and 11.9 °C against 9.4 °C) and lower than normal rainfalls (595.1 mm and 675.1 mm against 772 mm). In addition, 2006-2007 was characterised by exceptionally mild and dry winter and spring. This induced not only earlier growth stages but also a larger Gross Primary Productivity. On the contrary, lower Net Primary Productivity and crop productivity were observed on this year. This could be explained, on one hand by the drought in April 2007 and on the other hand to cloudy and humid conditions from end May to harvest. The first induced a stress in wheat plant which produced an unusually small flag leaf. The second induced an assimilation reduction due to low radiation and favoured disease development. The higher GPP and the lower productivity in 2006-2007 raise the question of carbon allocation. We supposed that, as the excess of carbon assimilated in 2006-2007 was not stored in grain or straw, it should have been stored in the roots. However, our biomass measurements did not allow confirming this hypothesi

Carbon balance of two Belgian crops

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Les géographes et le développement

Entre 2005 et 2008. sous la conduite de Christian Bouquet et Hélène Velasco-Graciet, trois colloques ont été organisés à la Maison des Sciences de l'Homme d'Aquitaine par le laboratoire ADES-CNRS pour essayer de clarifier la position de la géographie française par rapport aux ambiguïtés de la discipline face à la colonisation, à la tropicalité, et au développement. Après avoir tenté de savoir si la géographie coloniale était colonialiste (L'Empire des géographes), puis si la géographie tropicale était fille de la précédente et avait encore un sens (Les Tropiques des géographes), un ensemble de chercheurs ont affronte la question du « développement ». considéré comme le dernier terrain pour une géographie hors des murs occidentaux, pour confirmer ou infirmer qu'il s'agissait du dernier refuge possible pour ceux qui travaillent dans les Suds. Même si les hypothèses de départ ont été traitées avec d'infinies précautions car le débat n'est pas encore débarrassé des passions anciennes la filiation géographie coloniale / géographie tropicale / géographie du développement n'a pas été démontrée. Comme souvent, plus que des réponses, c'est une série de questions qui surgissent à la lecture des articles. En invitant les auteurs à s'interroger sur le lien qu'ils établissent entre leurs discours sur le développement et leurs actions concrètes dans ce domaine, les organisateurs savaient que le fossé entre les scientifiques et les experts ne serait pas comblé. Il reste donc à savoir pourquoi. En abordant dans son appel à communications le thème des Postcolonial Studies, le colloque a précisé des interrogations qu'il faudra continuer d'explorer. Enfin, en donnant la parole à plusieurs chercheurs originaires des anciennes colonies, cette rencontre a ouvert la porte à une décolonisation des esprits qui pourrait bientôt déboucher sur une géographie (enfin) décentrée. Cette quête épistémologique, qui a donné ici beaucoup de place au terrain, devra donc se poursuivre par le questionnement constant des principes et des pratiques des uns et des autres, en insistant sans doute davantage sur la géographie de l'Autre que sur une géographie de l'Ailleurs

Review of Legal Requirements on Ammonia and Greenhouse Gases Emissions from Animal Production Buildings in European countries

status: Published onlin