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International audience; Whether preclinical studies either involve a cell or animalmodel, the distribution of light plays a determinant role in the reproducibility of results of photodynamic therapy (PDT) studies. Unfortunately, only few illumination devices dedicated to preclinical studies are available and are for the most, very expensive. Mostresearch teams use home-made solutions that may not always be reproducible because of undefined light distribution, additive thermal emission, or unsuitable for shapes and volumes to illuminate. To address these issues, we developed illumination devices dedicated to our preclinical studies, which embed knitted light emitting fabrics (LEF) technology. LEF technology offers a homogeneous light distribution, without thermal emission and can be coupled with various light sources allowinginvestigation of several PDT modalities (irradiance, wavelength, illumination duration/mode). For in-vitro studies, we designed light plates,each allowing illumination of up to four 96-cells plates. For in-vivo studies, we designed mice boxes allowing three animals placement in prone position, equally surrounded by LEF and ensuring homogeneous extracorporeal illumination. Optical validation was performed and reproducibility of both preclinical systems were assessed. Both systems can deliver homogeneous light with an irradiance that can reachseveral mW/cm 2 , with varying durations and wavelengths. First results of preclinical studies demonstrate a high reproducibility, with an easy setup, and a great adaptability of illumination modalities with these devices based on light emitting fabrics.

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Key messageThe models we developed used palm stem diameter at 1.5m, stem density measured by core sampling at 1.5m, and the height of the palm to estimate palm stem biomass.AbstractAllometric equations based on non-destructive methods were developed to estimate palm stem biomass. Twenty mature palms of different ages were subject to destructive and non-destructive measurements: stem height from the collar to the bottom of the frond at the 33rd position in the crown (frond 33), dry weight, the diameter and thickness of cylindrical slices sectioned at different heights along the stem, and the dry weight of samples of stem tissue taken from the core of each slice. The densities of the stem slices obtained using the destructive method (D-true) and the non-destructive method (D-core) were linearly correlated: D-true=1.062xD(core) (R-2=0.99) independently of the height, age and genetic origin of the palm. Stem density varied with height, reaching its maximum at around 1.5m, after which it remained more or less constant to the top of the stem. Stem linear density (SLD) estimated from the product of the density and the section of the stem fell to a threshold value that remained more or less constant above 1.5m. SLD between observed slices was estimated by interpolation based on a hyperbolic model to compute the true biomass of each palm. An equation derived from the integral of the hyperbolic model was fitted to estimate palm stem biomass as a function of wood density observed by non-destructive sampling at 1.5m on the stem and of the diameter at the same height. With this equation, palm stem biomass can be estimated with an error of 5%.

Description du sujet. Au Bénin, la culture du palmier à huile est largement répandue en milieu villageois. L’étude porte sur l’impact du recyclage des feuilles d’élagage sur les propriétés du sol des palmeraies.Objectifs. Évaluer l\'effet de deux modes de gestion des feuilles élaguées dans la palmeraie sur le stock de carbone et les propriétés physico-chimiques du sol.Méthode. Six palmeraies villageoises de deux classes d\'âges (7-12 ans et 13-24 ans) ont été retenues dans le sud-est du Bénin afin de comparer les propriétés du sol de deux zones : les zones de restitution totale des feuilles d\'élagage (RT) et celles de restitution nulle des feuilles (RN) représentant le témoin. Dans chaque palmeraie, le sol sous chaque modalité de recyclage des feuilles a été prélevé, sur fosses, jusqu’à 50 cm de profondeur à proximité de six palmiers. Les propriétés du sol ont été déterminées par des méthodes d’analyse conventionnelles et par la spectroscopie proche infrarouge.Résultats. Les stocks de carbone et d\'azote sous RT à l\'âge adulte sont de 58 Mg·ha-1 et 4,3 Mg·ha-1, respectivement et sont significativement supérieurs aux stocks dans tous les autres traitements (34,6 Mg C·ha-1 et 2,9 Mg N·ha-1). Le recyclage des feuilles a amélioré la fertilité du sol jusqu’à 20 cm de profondeur dans les palmeraies adultes. La porosité et la densité apparente du sol ont été aussi améliorées.Conclusions. La gestion des feuilles élaguées dans les palmeraies modifie les propriétés du sol qui sont nettement améliorées en surface après 10 ans de recyclage des feuilles., Effect of management of pruned fronds of oil palm on soil carbon stock and soil physico-chemical properties in Beninese smallholder plantationsDescription of the subject. In Benin, oil palm plantations are widely managed by smallholder farmers. The study addresses the impact on soil properties of the recycling of pruned fronds from these trees.Objectives. The study aims to assess the effect of two modes of management of pruned fronds on the carbon stock and physico-chemical properties of soil.Method. Six oil palm plantations were selected to represent two age classes (7-12 years and 13-24 years) in southeastern Benin. They were used to compare the soil properties of two areas: the areas of total recycling of pruned fronds (TR) and the areas of no recycling of the fronds (NR), which represented the control. In each plantation, soil samples were collected under the two treatments, from holes of up to 50 cm depth, near six oil palm trees. The soil properties were determined using conventional laboratory methods and near-infrared spectroscopy method.Results. Carbon and nitrogen stocks under TR of adult plantations were 58 Mg·ha-1 and 4.3 Mg·ha-1, respectively, and were significantly higher than the stocks in all other treatments (34.6 Mg C·ha-1 and 2.9 Mg N·ha-1). Recycling of pruned fronds improved soil fertility at a depth of up to 20 cm in the adult plantations. The porosity and bulk density of the soil were also improved.Conclusions. The management of the pruned fronds in the smallholders\' oil palm plantations modified the soil properties, which were significantly improved in the top soil after 10 years of frond recycling.

In Sudano-Sahelian agriculture, organic amendments are often limited by resource availability. Small branches (ramial wood, RW) represent an organic resource found in many landscapes but little is known about their effects. This field trial (2007–2009) studied the effects of RW or straw at low application rate (0.69 Mg C ha−1 year−1) on topsoil carbon (C), nitrogen (N) and available phosphorus (P, Pav), termite cast abundance, and sorghum yield. Straw and RW were chopped and either buried (StBu, WoBu) or mulched (StMu, WoMu). Mineral fertilizers were added to straw so that RW- and straw-amended plots received similar applications of C, N, P, and potassium. Another treatment had RW buried with additional N (WoBuN), and there was a control (Ctrl). Branches came from Piliostigma reticulatum, very common in the area. The treatments had little significant effect on topsoil and crop, owing to the low application rate and spatial variability. However, Pav was significantly lower with buried than mulched amendments in 2009, and decreased significantly over time in Ctrl and with buried amendments. Topsoil C also decreased significantly with time in WoMu. Significantly more termite casts were observed with RW. The sorghum yield averaged 0.87 Mg DM ha−1 in 2007 and then decreased. The treatments affected yield significantly in 2008 only: it was higher in WoBuN and StBu than in Ctrl. In 2009, the yield was mainly affected by initial topsoil Pav. These results suggest that RW stimulated biological activity, leading to P immobilization and C mineralization, but had little effect on yields.

Une typologie des palmeraies villageoises du département du Plateau au sud-est du Bénin a été établie à travers : i) une étude cartographique de la couverture pédologique et d'occupation des sols, ii) des entretiens semi-structurés en assemblée générale avec des groupes de producteurs choisis de façon aléatoire dans chaque commune, iii) des entretiens semi-structurés individuels avec quatre vingt dix producteurs dont les palmeraies sont installées sur les terres de barre et étudiées par une analyse factorielle des correspondances multiples. Les terres de barre sont les sols les plus plantés avec le palmier à huile et Adja-Ouèrè et Sakété constituent les communes de grosse production. Les palmeraies du département présentent i) des caractéristiques très peu variables : la densité de plantation, le précédent cultural, les pratiques d'association des cultures vivrières et d'utilisation des engrais et ii) des caractéristiques variables et spécifiques : la restitution des sous-produits de transformation et le recyclage des feuilles d'élagage des palmiers. Parmi les cinq modalités de gestion des feuilles d'élagage identifiées, l'exportation des feuilles est une pratique dominante dans le département. Sur les terres de barre, on retrouve quatre types de palmeraies qui se différencient par la superficie, les pratiques culturales et l'âge des palmeraies.Mots clés: Palmeraies villageoises, sols, sud-Bénin, pratiques culturales, typologie, palmier à huile.