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The growing demand for sustainable agriculture is raising interest in intercropping for its multiple potential benefits to avoid or limit the use of chemical inputs or increase the production per surface unit. Predicting the existence and magnitude of those benefits remains a challenge given the numerous interactions between interspecific plant-plant relationships, their environment and the agricultural practices. Soil-crop models are critical in understanding these interactions in dynamics during the whole growing season, but few models are capable of accurately simulating intercropping systems. In this study, we propose a set of simple and generic formalisms for simulating key interactions in intercropping systems that can be readily included into existing dynamic crop models. This requires simulating important processes such as development, light interception, plant growth, N and water balance, and yield formation in response to management practices, soil conditions, and climate. These formalisms were integrated into the STICS soil-crop model and evaluated using observed data of intercropping systems of cereal and legumes mixtures, including Faba bean-Wheat, Pea-Barley, Sunflower-Soybean, and Wheat-Pea mixtures. We demonstrate that the proposed formalisms provide a comprehensive simulation of soil-plant interactions in various types of bispecific intercrops. The model was found consistent and generic under a range of spring and winter intercrops (nRMSE = 25% for maximum leaf area index, 23% for shoot biomass at harvest, and 18% for yield). This is the first time a complete set of formalisms has been developed and published for simulating intercropping systems and integrated into a soil-crop model. With its emphasis on being generic, sufficiently accurate, simple, and easy to parameterize, STICS is well-suited to help researchers designing in silico the agroecological transition by virtually pre-screening sustainable, manageable intercrop systems adapted to local conditions.

Introduction. À la différence des grandes cultures, le fonio, une céréale négligée, n’a pu bénéficier d’un grand nombre de recherches formalisées sur les techniques culturales. Sur la base d’une recherche documentaire systématisée, cet article présente une analyse critique des techniques pratiquées en culture du fonio en Afrique subsaharienne. Littérature. Le fonio est cultivé au regard de ses potentiels alimentaire, socioculturel, thérapeutique, économique voire fourrager. Peu exigeant, il se développe dans une large gamme de conditions pédoclimatiques avec une préférence pour les sols légers et riches en matières organiques, et les zones à pluviométrie annuelle moyenne de 900-1 000 mm. Dans les pays producteurs, les variétés et les techniques culturales sont demeurées traditionnelles. Les semis se font principalement à la volée. Contrairement aux autres céréales, le fonio se cultive assez souvent sans fumure minérale ni pesticide chimique et apparait comme une culture biologique valorisable en agroécologie. Les rendements sont généralement faibles et souvent inférieurs à 1 t·ha-1. Ceci est surtout lié à l’absence de variétés améliorées et de pratiques culturales appropriées, au phénomène de verse, à l’égrenage spontané et au défaut de remplissage des grains. Conclusions. Les pratiques culturales du fonio, restées traditionnelles, sont caractérisées par la pénibilité des opérations et la faiblesse des rendements. Des recherches innovantes sur les variétés, les techniques culturales et sur la mécanisation et la rentabilité permettront de lever les contraintes et de favoriser une relance effective de la production. Diversity of techniques and cultivation practices of fonio millet (Digitaria exilis S.) in West Africa. A review Introduction. Unlike field crops, fonio, known to be a neglected plant, has not benefited sufficiently from formalized research on crop techniques. Based on systematic documentary research, this article presents a critical analysis of techniques practiced in fonio cultivation in Sub-Saharan Africa. Literature. Fonio is cultivated not only as a foodstuff, but also for its potential socio-cultural, therapeutic, and economic benefits, and even for use as forage. The cereal develops in a wide range of soil and climate conditions, with a preference for light soils that are rich in organic matter, and areas with an average annual rainfall of 900-1,000 mm. In producing countries, fonio varieties and cultivation techniques have remained traditional. Sowing is done mainly by broadcasting. Unlike other staple cereals, fonio is quite often grown without the application of chemical fertilizers or pesticides, and it appears to be a valuable biologic crop in agroecology. Yields are generally low and often less than 1 t·ha-1. This is mainly due to the absence of improved varieties and appropriate crop practices, and to lodging phenomena, seed shattering and lack of grain filling. Conclusions. Fonio cultivation practices have remained traditional, characterized by difficult operations and low yields. Innovative research on varieties and cultivation techniques, and on mechanization and profitability, will remove constraints and promote an effective revival of production.

Description du sujet. La fertilisation microdose a été développée pour la production des légumes feuilles africains (LFA) afin de réduire les doses élevées de fertilisants souvent appliquées pour leur production en Afrique de l'Ouest. Objectifs. Cette étude vise a (i) évaluer la réponse de trois légumes-feuilles africains (LFA, Amaranthus cruentus L., Solanum macrocarpon L. et Ocimum gratissimum L.) a l'apport combiné du fumier de bovins et d'urée en microdose puis (ii) évaluer leur facteur partiel de productivité de l'azote. Méthode. Des expérimentations en station ont été conduites durant trois saisons culturales (2015 a 2017) au Nord Bénin. Six doses d'urée-N : 0, 10, 20, 30, 40 et 60 kg.ha-1 combinées a 5 l·ha-1 de fumier de bovins (M5N0, M5N10, M5N20, M5N30, M5N40 et M5N60, respectivement) et l'application exclusive de 40 (M0N40) et 80 kg d'uree-N·ha-1 (M0N80) comme témoin et deux temps d'application de l'urée (T1 = 0 et T2 = 14 jours apres le repiquage) ont été testés dans un dispositif en blocs aléatoires complets avec quatre répétitions. Resultats. Le traitement M5N60 a enregistré le rendement en légume frais de A. cruentus le plus élevé, avec une amélioration de 90 et 151 % par rapport a M5N0 et les deux traitements M0N40 et M0N80, respectivement, tandis que le traitement M5N40 a amélioré le rendement frais de S. macrocarpon de 23 % par rapport a M5N0. Cependant, aucune différence significative n'a été observée entre les différentes doses d'urée-N appliquées sous O. gratissimum. De plus, la période d'application de l'engrais n'a affecté ni le rendement frais ni le facteur partiel de productivité d'aucune des especes de légume étudiées. Conclusions. Le microdosage combiné de fumier et d'urée constitue une pratique prometteuse de gestion des nutriments en Afrique de l'Ouest pour la production des LFA car elle permet d'améliorer les rendements tout en économisant les engrais pour les petits producteurs de légumes.

Estimating winter wheat yield through the decreasing phase of its green area. A large number of agrometeorological models for crop yield assessment are available with various levels of complexity and empiricism. However, the current development of models for wheat yield forecasting does not always reflect the inclusion of the loss of valuable green area and its relation to biotic and abiotic processes in production situation. In this study the senescence phase of winter wheat (Triticum aestivum L.) is monitored through the GAI (Green Area Index), calculated from digital hemispherical photographies taken over plots in Belgium, Grand-Duchy of Luxembourg and France. Two curve-fitting functions (modified Gompertz and modified logistic) are used to describe the senescence phase. Metrics derived from these functions and characterizing this phase (i.e. the maximum value of GAI, the senescence rate and the time taken to reach either 37% or 50% of the green surface in the senescent phase) are related to final grain yields. The regression-based models calculated with these metrics showed that final yield could be estimated with a coefficient of determination of 0.83 and a RMSE of 0.48 t.ha-1. Such simple models may be considered as a first yield estimates that may be performed in order to provide a better integrated yield assessment in operational systems. Indeed, estimation of cereal-crop production, particularly wheat, is considered as a priority in most crop research programs due to the relevance of food grain to world agricultural production. [PUBLICATION ABSTRACT]

To counteract environmental problems due to agricultural intensification, European farmers can apply agri-environmental schemes in their fields. Flower strips are one example of these schemes, with the aim of supporting biodiversity, leading to an increase in \"useful\" species groups such as pollinators for crop pollination and natural enemies for pest control. However, to our knowledge, a complete appraisal of the pros and cons of flower strips, from a farmer's point of view, does not yet exist. It is proposed that better and more complete information could increase the adoption and implementation of such agri-environmental schemes. This study aims 1) to assess the pros and cons of flower strips, from a farmer's point of view, and 2) to highlight the knowledge gaps that exist in the scientific literature, for the different types of pros and cons. We listed the different components of the appraisal of pros and cons and conducted a systematic screening of the scientific literature on flower strips and these components. The largest part of the 31 selected studies was concerning agronomical and ecological processes, such as pollination and animal pest control. Most of them indicated positive effects of flower strips. For many components of the appraisal, mostly economic and social ones, few or no studies were found. While a positive balance of pros and cons, from a farmer's point of view, came from our literature screening, large research gaps still remain and more research is required, especially in the economic and social components of the evaluation.

This study assesses the accuracy of state-of-the-art regional climate models for agriculture applications in West Africa. A set of nine regional configurations with eight regional models from the ENSEMBLES project is evaluated. Although they are all based on similar large-scale conditions, the performances of regional models in reproducing the most crucial variables for crop production are extremely variable. This therefore leads to a large dispersion in crop yield prediction when using regional models in a climate/crop modelling system. This dispersion comes from the different physics in each regional model and also the choice of parametrizations for a single regional model. Indeed, two configurations of the same regional model are sometimes more distinct than two different regional models. Promising results are obtained when applying a bias correction technique to climate model outputs. Simulated yields with bias corrected climate variables show much more realistic means and standard deviations. However, such a bias correction technique is not able to improve the reproduction of the year-to-year variations of simulated yields. This study confirms the importance of the multi-model approach for quantifying uncertainties for impact studies and also stresses the benefits of combining both regional and statistical downscaling techniques. Finally, it indicates the urgent need to address the main uncertainties in atmospheric processes controlling the monsoon system and to contribute to the evaluation and improvement of climate and weather forecasting models in that respect.

This study investigated the effect of high temperature and drought (during grain-filling) on the quality and components yield of five winter wheat varieties. Drought and drought + heat were found to have a much greater influence on the yield and quality than heat stress alone. Averaged over the varieties, the yield losses were 57% after drought, 76% after drought + heat, and only 31% after heat stresses. The reductions in the unextractable polymeric protein fraction and glutenin-to-gliadin ratio indicated a poorer grain yield quality, despite the higher protein content. Quality deterioration was observed after drought or drought + heat, while high temperatures alone resulted in no change or in a better ratio of protein components. A significant negative correlation was observed between starch granule size and relative protein content after drought.

The genetic basis of heterosis was investigated in all elite rice hybrid by using a molecular linkage map with 150 segregating loci covering the entire rice genome. Data for yield and three traits that were components of yield were collected over 2 years from replicated field trials of 250 F2:3 families. Genotypic variations explained from about 50% to more than 80% of the total variation. Interactions between genotypes and years were small compared with the main effects. A total of 32 quantitative trait loci (QTLs) were detected for the four traits; 12 were observed in both years and the remaining 20 were detected in only one year. Overdominance was observed for most of the QTLs for yield and also for a few QTLs for the component traits. Correlations between marker heterozygosity and trait expression were low, indicating that the overall heterozygosity made little contribution to heterosis. Digenic interactions, including additive by additive, additive by dominance, and dominance by dominance, were frequent and widespread in this population. The interactions involved large numbers of marker loci, most of which individually were not detectable on single-locus basis; many interactions among loci were detected in both years. The results provide strong evidence that epistasis plays a major role as the genetic basis of heterosis

Cleft grafting methods were applied in order to evaluate the effect of grafting on tomato fruit yield and quality. The tomato cultivars used as scions were Yeni Talya, Swanson and Beri. The cultivars Beaufort and Arnold were used as rootstocks. The following characteristics of grafted and nongrafted plants were recorded: fruit index, number of fruits/truss, fruit weight, fruit yield, dry matter, pH, concentration of soluble solids, titratable acidity, concentrations of total sugar, lycopene and vitamin C. The results showed that fruit yield and fruit index, number of fruits/truss and fruit weights were improved by grafting. Fruit quality, measured in terms of concentrations of dry matter, soluble solids, total sugar, and vitamin C, was lower in grafted plants than in nongrafted ones. No significant difference in lycopene level and pH was found. Titratable acidity was improved by grafting. A positive effect of grafting was recorded when Beaufort was used as rootstock. These results showed that grafting could be an advantageous alternative in tomato production.

The antimicrobial activity of six plant extracts from Ocimum basilicum, Azadirachta indica, Eucalyptus chamadulonsis, Datura stramonium, Nerium oleander, and Allium sativum was tested for controlling Alternaria solani in vitro and in vivo. In in vitro study the leaf extracts of D. stramonium, A. indica, and A. sativum at 5% concentration caused the highest reduction of mycelial growth of A. solani (44.4, 43.3 and 42.2%, respectively), while O. basilicum at 1% and 5% concentration and N. oleander at 5% concentration caused the lowest inhibition of mycelial growth of the pathogen. In greenhouse experiments the highest reduction of disease severity was achieved by the extracts of A. sativum at 5% concentration and D. stramonium at 1% and 5% concentration. The greatest reduction of disease severity was achieved by A. sativum at 5% concentration and the smallest reduction was obtained when tomato plants were treated with O. basilicum at 1% and 5% concentration (46.1 and 45.2 %, respectively). D. stramonium and A. sativum at 5% concentration increased the fruit yield by 76.2% and 66.7% compared to the infected control. All treatments with plant extracts significantly reduced the early blight disease as well as increased the yield of tomato compared to the infected control under field conditions.