Vers une stabilisation de la production de colza sous contrainte : valorisation de la plasticité de la morphologie aérienne et de sa variabilité génotypique

Vers une stabilisation de la production de colza sous contrainte : valorisation de la plasticité de la morphologie aérienne et de sa variabilité génotypiqu

Production maximale de matière sèche et rayonnement solaire intercepté par un couvert végétal

International audienc

Are yield and biomass distribution affected by sink organ clipping during reproductive phase of winter oilseed rape (Brassica napus L.)?

As many crops, Winter Oilseed Rape plants are sensitive to biotic or abiotic stresses, but, due to its plasticity reproductive organ losses can be compensated. In this case, biomass is allocated to remaining organs changing yield distribution within the plant. However, compensation remains variable and causes of this variability are still not completely understood. Due to sequential development, pod yield is distributed among axes unevenly. Indeed biomass of axis and biomass allocation to pods varies according to axis position. We suppose that efficiency of compensation at plant scale would depend on the position of axis implied. In the following study axes were clipped. Yield and biomass distribution within plant as well as efficiency of biomass allocation to reproductive organs were characterized. Our data assume that basal axe were mainly involved in compensation and that increase in pod yield on these axes was related to increase in dry mass with no modification of the efficiency allocation of biomass

Insights into temperature effects on the fatty acid composition of oilseed rape varieties

Conventional oilseed rape (OSR) and high-oleic low-linolenic (HOLL) varieties were compared for their temperature sensitivity during 10 years of variety testing in Switzerland. A high variability in alpha-linolenic acid (ALA) content among locations and years was noticed for both types of varieties (6.3% to 11.4% for conventional varieties, 2.1% to 4.6% for HOLL ones). Average minimum temperature was registered during seed filling, between 680° and 930° days after the onset of flowering. They ranged from 9.2 °C and 17.5 °C and were negatively correlated to ALA content in the seeds at harvest. Additionally to lower ALA contents, HOLL varieties had a smaller response to temperature, as compared to conventional cultivars. When studying each variety independently, small but significant differences appeared among varieties of the same group (HOLL or conventional). Among conventional varieties, differences were observed only in oleic acid desaturation, whereas linoleic acid desaturation efficiency was similar for the studied cultivars. Conversely, in HOLL varieties, linoleic acid desaturation was reduced by mutations and not affected by temperature, resulting in lower ALA content and a lower sensitivity to temperature. Each OSR variety could be characterized by the regression parameters for their specific response to minimum temperature in the adequate period, with two distinct groups for conventional and HOLL varieties. A single model for each variety group was built to predict ALA content at harvest, based simply on minimal temperature during the period. The model was then tested on an independent data set. Combinations with the model BRASNAP-PH to predict onset of flowering made it possible to simulate ALA content without field observations, knowing only sowing date and meteorological data. A sensitivity analysis was performed to determine which precision was required on flowering date and the importance of knowing cultivar characteristics. Our results showed that ALA content prediction was possible, although flowering date was only estimated with a precision of 3 days. In spite of differences among varieties for their temperature sensitivity (R2 varying from 0.39 to 0.89 among tested varieties), a general equation can give a satisfying prediction for conventional varieties within the observed range of temperature, (y = −0.41x + 13.7, with x = minimum temperature registered during the sensitive period, R2 = 0.52, p < 0001). Therefore, using this general model could be used to test the potential of a new production site or assess the quality variability upon time or among different locations

Production maximale de matiere seche et rayonnement solaire intercepte par un couvert vegetal

National audienceA linear relationship has been established for many crops between dry matter production and radiation intercepted by the crop. These results have led us to propose a model to estimate the potential productivity of a crop. Moreover, it is possible to quantify the effects of length-of growth period, position of this growth period during the year and rate of leaf area establishment. A specific example is given for maize in the North of France.De nombreux résultats concernant la relation entre la production de matière sèche totale et le rayonnement intercepté par la culture permettent de proposer un modèle simple d’estimation de la production potentielle d’une espèce donnée dans un lieu donné. De plus, ce type de démarche a permis de proposer une méthode pour quantifier l’effet de la durée de végétation, de la position du cycle de végétation dans l’année et de la vitesse de mise en place de surface foliaire. Un exemple précis est donné pour une culture de maïs dans le Nord de la France

Modelling winter oilseed rape carbon accumulation during the reproductive phase

Actes sur CDROMInternational audienceThe observed decrease in oilseed rape conversion of intercepted radiation efficiency during reproductive phase could be due to leaf falling off, pod senescence or to the specific energy cost of oil production. In reason of its interest in modelling, we tried to identify and quantify the processes really involved in this decrease, for different genotypes under contrasted nitrogen fertilisations

Use of a structural-functional plant model to assess the morphogenetical plasticity. How does variation in phyllochron impact plant growth and development of Brassica napus in the GreenLab model

Use of a structural-functional plant model to assess the morphogenetical plasticity. How does variation in phyllochron impact plant growth and development of Brassica napus in the GreenLab model. 4. International Symposium PMA 1

Model calibration on two oilseed rape varieties (Brassica Napus L.), comparison and perspectives

Actes sur CDROMabsen

Use of a structural-functional plant model to assess the morphogenetical plasticity. How does variation in phyllochron impact plant growth and development of Brassica napus in the GreenLab model

Use of a structural-functional plant model to assess the morphogenetical plasticity. How does variation in phyllochron impact plant growth and development of Brassica napus in the GreenLab model. 4. International Symposium PMA 1

Levers of tolerance to floral bud damage in Brassica napus

poster, + poster abstractInternational audienc