Caractérisation de la sécheresse agronomique en zone aride. I. Présentation d'un modèle simple d'évaluation appliqué au cas de l'arachide cultivée au Sénégal

La caractérisation des formes de sécheresses agronomiques constitue l'étape préalable indispensable dans la réalisation d'un programme d'amélioration des rendements en zones semi-arides. Dans le cas de l'arachide cultivée au Sénégal, un modèle simplifié associant les concepts d'évapotranspiration et de bilan hydrique à des données élémentaires sur la réponse des plantes à la sécheresse a été développé. Après une présentation de ce modèle il est montré qu'il permet d'effectuer une simulation satisfaisante du bilan hydrique de cette espèce constituant ainsi un outil performant de diagnostic des types de sécheress

Gendered Impact of Irrigated Rice Schemes’ Governance on Farmers’ Income, Productivity and Technical Efficiency in Benin

Collective actions groups have many advantages and are sometimes essential, yet they can reinforce or perpetuate inter-and intra-gender inequalities when their functioning is left entirely subject to internal community dynamics and they are not well managed. This is well illustrated by the case of Koussin-Lélé rice scheme in the central Benin. This paper apply inequality indices and frontier production function to data from a sample of male and women rice farmers to analyze the gender inequalities in access to land and the governance of the groups, and their gender-differentiated impacts on farmers' productivity, technical efficiency and income. The results show that women are particularly discriminated against with regards to access to land, with significant negative impacts on their productivities and incomes. However, this discrimination did not have a significant impact on technical efficiency.Gender, land distribution, Rice, technical efficiency, productivity, income, Agricultural and Food Policy, Consumer/Household Economics, Demand and Price Analysis, Farm Management, Food Consumption/Nutrition/Food Safety, Food Security and Poverty, International Relations/Trade, Marketing, Productivity Analysis, Research and Development/Tech Change/Emerging Technologies,

Why NERICA is a successful innovation for African farmers

This paper responds to ‘Funding international agricultural research and the need to be noticed: a case study of NERICA rice’ by Stuart Orr, James Sumberg, Olaf Erenstein and Andreas Oswald, published in this issue of Outlook on Agriculture. In summary, the article by Orr et al, based on an internal WARDA document written in November 2003 and augmented with results from Internet searches, is outdated and does not seem to be fair, objective or useful. We invite the authors to visit WARDA or any of its partners in Sub-Saharan Africa for evidence of the impact of NERICA varieties or the other improved varieties and technologies that have been developed and disseminated by WARDA in recent years

A Study of Machine Learning Techniques for Daily Solar Energy Forecasting using Numerical Weather Models

Proceedings of: 8th International Symposium on Intelligent Distributed Computing (IDC'2014). Madrid, September 3-5, 2014Forecasting solar energy is becoming an important issue in the context of renewable energy sources and Machine Learning Algorithms play an important rule in this field. The prediction of solar energy can be addressed as a time series prediction problem using historical data. Also, solar energy forecasting can be derived from numerical weather prediction models (NWP). Our interest is focused on the latter approach.We focus on the problem of predicting solar energy from NWP computed from GEFS, the Global Ensemble Forecast System, which predicts meteorological variables for points in a grid. In this context, it can be useful to know how prediction accuracy improves depending on the number of grid nodes used as input for the machine learning techniques. However, using the variables from a large number of grid nodes can result in many attributes which might degrade the generalization performance of the learning algorithms. In this paper both issues are studied using data supplied by Kaggle for the State of Oklahoma comparing Support Vector Machines and Gradient Boosted Regression. Also, three different feature selection methods have been tested: Linear Correlation, the ReliefF algorithm and, a new method based on local information analysis.Publicad

Aménagements hydro-agricoles et santé (vallée du fleuve Sénégal)

La transmission du paludisme dans le delta du fleuve Sénégal a été étudiée dans trois villages, deux villages de riziculture irriguée dont un d'aménagement récent et un village de culture pluviale traditionnelle. La riziculture irriguée a entraîné une pullulation de moustiques et principalement d'#Anopheles pharoensis. La densité de ses populations est très importante et liée aux cycles des cultures dans la zone rizicole, son indice d'anthropophilie est élevé mais la longévité des femelles est très faible. #An. gambiae s.l. vecteur majeur du paludisme au Sénégal est, dans le delta, remplacé par #An. pharoensis$, vecteur secondaire dont l'aptitude à assurer une bonne transmission n'est pas prouvée. La riziculture irriguée n'a pas entraîné une augmentation de la transmission du paludisme. (Résumé d'auteur

Heart of endosymbioses : transcriptomics reveals a conserved genetic program among arbuscular mycorrhizal, actinorhizal and legume-rhizobial symbioses

To improve their nutrition, most plants associate with soil microorganisms, particularly fungi, to form mycorrhizae. A few lineages, including actinorhizal plants and legumes are also able to interact with nitrogen-fixing bacteria hosted intracellularly inside root nodules. Fossil and molecular data suggest that the molecular mechanisms involved in these root nodule symbioses (RNS) have been partially recycled from more ancient and widespread arbuscular mycorrhizal (AM) symbiosis. We used a comparative transcriptomics approach to identify genes involved in establishing these 3 endosymbioses and their functioning. We analysed global changes in gene expression in AM in the actinorhizal tree C. glauca. A comparison with genes induced in AM in Medicago truncatula and Oryza sativa revealed a common set of genes induced in AM. A comparison with genes induced in nitrogen-fixing nodules of C. glauca and M. truncatula also made it possible to define a common set of genes induced in these three endosymbioses. The existence of this core set of genes is in accordance with the proposed recycling of ancient AM genes for new functions related to nodulation in legumes and actinorhizal plants