Effets de Dix (10) Variétés de Sésame (Sesamum indicum (L.)) en Association avec Le Niébé (Vigna unguiculata (L.) Walp) dans la Lutte Contre Striga Gesnerioïdes (Willd.) Vatke. au Niger

Striga gesnerioïdes est une plante parasite qui cause des dégâts importants sur le niébé et les méthodes de lutte testées restent insatisfaisantes. L’étude vise à mettre au point, une référence de technique d’association sésame-niébé pour contribuer à lutter efficacement contre Striga gesnerioïdes. À cet effet, un dispositif en Split-Plot est utilisé sur un terrain naturellement infesté par Striga gesnerioïdes. Trois comptages à des périodes différentes (42, 56 et 70 jours après semis) du nombre de plants de Striga gesnerioïdes émergés par poquet de niébé ont été réalisés. Ainsi, en association dans le même poquet (sésame + niébé), les variétés de sésame EF 146, HC 110, ICN 130, HB 168, Vgr 156 et EF 147 sont efficaces pour atténuer l’émergence de striga. En alternance de poquets (niébé et sésame), les variétés de sésame EF 146, HC 110, ICN 137, EF 147 et 38-1-7 sont efficaces contre striga. Et les variétés de sésame EF 146, Vgr 156, HC 108 et 38-1-7 ont montré leurs efficacités en alternance de lignes avec le niébé. EF 146 est la seule variété de sésame efficace dans toutes les trois mesures de protections. Ces résultats pourraient être vulgarisés au niveau des producteurs de niébé pour booster sa production au niveau national, voir mondial. Striga gesnerioïdes is a parasitic plant that causes significant damage to cowpea and the control methods tested remain unsatisfactory. The study aims to develop a technical reference of sesame-cowpea association to contribute to the effective control of Striga gesnerioïdes. For this purpose, a Split-Plot device is used on land naturally infested by Striga gesnerioïdes. Three counts at different periods (42, 56 and 70 days) of the number of emerged Striga gesnerioïdes plants per cowpea were made. Thus, in combination in the same plot (sesame + cowpea), the sesame varieties EF 146,HC 110, ICN 130, HB 168, Vgr 156 and EF 147 are effective in mitigating Striga emergence. In alternating rows (cowpea and sesame), the sesame varieties EF 146, HC 110, ICN 137, EF 147 and 38-1-7 were effective against striga. And the sesame varieties EF 146, Vgr 156, HC 108 and 38-1-7 showed their efficacy in alternating rows with cowpea. EF 146 is the only sesame variety that is effective in all three protective measures. These results could be disseminated to cowpea producers to boost its production at the national and even global level

Amélioration variétale du sésame (Sesamum indicum L.) par mutation induite: effet de la mutagenèse sur la tolérance à la sécheresse et la productivité

This study focused on the induction of genetic variability in sesame (Sesamum indicum L.) through radiation mutation with the purpose of contributing in broadening the genetic base of sesame and improving sesame yield in drought conditions in Senegal. Therefore, sesame seeds that originated from Senegal were exposed to gamma radiations of different levels to induce mutations. Germinating mutant seedlings were screened for drought resistance using Polyethylene glycol (PEG) 6000. Vegetative genotypes were subsequently on-grown in a glasshouse under limited irrigation to determine water deficit tolerance. Finally, genotypes were tested in the field for their yield potential with or without moisture stress. The key findings of this work were that radiations levels ranging from 300 to 400 Gy were efficient enough in generating a wide range of genetic variability with viable mutations in sesame. Moisture deficit corresponding to -1 MPa is the limit beyond which sesame seeds do not germinate. In the mild moisture stress treatment (-0.5 MPa), radicle elongation was promoted for the majority of the genotypes tested when compared to the control plants. During the drought tolerance screening at vegetative stage in glasshouse, the technique of chlorophyll fluorescence was used to evaluate the response to moisture stress of induced-genotypes of sesame by suspending the water supply to plants. Results showed that the maximum quantum yield of primary photochemistry (FV/FM) was less sensitive than performance index (PIABS) to moderate water stress. The drought factor index, calculated from PIABS, is proposed in this work to screen for improved drought tolerance in sesame. Genotypic variation for drought tolerance was evidenced in the mutated population at reproductive stage and several induced-mutants out-yielded the parental sources in drought conditions. In Conclusion, the use of induced mutation technique has allowed the induction of a great genetic variation in the sesame base collection of Senegalese Institute of Agricultural Research and obtaining mutants that out-yielded the parental sources in drought conditions

ANALYSIS OF THE PROFITABILITY OF PICS BAGS FOR THE STORAGE OF BAMBARA GROUNDNUT SEEDS IN THREE REGIONS OF NIGER

This study documents Bambara groundnut storage practices and estimates the economic returns from alternative storage and marketing strategies in Niger. A random sample of Bambara groundnut growers in the main Bambara groundnut growing areas of Niger were interviewed. A total of 164 respondents participated. Slightly over half of the Bambara groundnut stored is in potentially hermetic containers including double and triple layer bags, plastic jugs and metal drums. Use of storage insecticide varied by region. Over 12% of the quantity stored was treated with insecticide in the Maradi Region, but only about 2% in the other regions. Use of the Purdue Improved Crop Storage bag also varied by region. In the Dosso region in 2012, 47% of the Bambara groundnut was stored in PICS bags, but only 8% in Maradi and 4% in Zinder. Bambara groundnut prices vary seasonally, and they vary widely from market to market. Consequently, marketing flexibilty is key to profitable commecialization. In most cases storing into the next rainy season (i.e. 8 to 9 months) is the most profitable strategy. Estimates indicate that producers using traditional storage technologies should market their Bambara groundnuts quickly because the storage damage can be severe. In contrast, PICS bags are quite profitable for Bambara groundnut producers in the study areas, especially when longer-term storage conditions are required. Even when the PICS bag is only used one season, the simple rate of return is over 100%

ANALYSIS OF THE PROFITABLILITY OF PICS BAGS FOR THE STORAGE OF ROSELLE GRAINS (Hibiscus sabdariffa) IN THREE REGIONS IN NIGER

Roselle is a multipurpose crop produced for its grain, as well as flowers used in making teas and therapeutic preparations. The study is based on interviews with 164 randomly selected Roselle producers in Dosso, Maradi and Zinder Regions of Niger. Farmers store roselle grain in various containers, such as woven bags, plastic jugs, plastic bags, granaries, etc. which are mostly non-hermetic. Some store with the addition of wood ash, neem leaves (Azadirachta indica), sand or insecticide. Plastic jugs, granaries and plastic bags are used mainly for storing small amounts of roselle while metal drums and woven polypropylene bags are reserved for larger quantities. Overall the portion of roselle grain stored in 2012 in potentially hermetic containers was: Dosso, 22%; Maradi, 29% and Zinder, 26%. In 2012, the percentage reported stored in PICS triple bags was Dosso, 4%; Maradi, 2% and Zinder, 2%. The percentage of the grain quantity stored with insecticide in 2012 was Dosso, 26%; Maradi, 13%, and Zinder zero. The analysis of price fluctuations shows that about 7 months of storage is required for the producers to take advantage of price seasonality. Rozelle prices also vary widely from market to market. Consequently, marketing flexibility is key to profitable commercialization. In most cases storing into the next rainy season (i.e. 7 months) is the most profitable strategy. It is clear from this analysis that the PICS bags are a potential source of profitability for roselle producers in the study areas especially when the storage period is relatively long. For example, the simple rate of return is over 100% even when the PICS bag is only used one year compared to selling at harvest. PICS technology is much more cost effective than the traditional method of storage. After 7 months of storage without either insecticide or hermetic storage method, the return on investment is largely negative because of very high storage losses

Screening for drought tolerance in mutant germplasm of sesame (Sesamum indicum L.) probing by chlorophyll a fluorescence

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Radiosensitivity of African sesame cultivars to gamma-rays

The effects of gamma irradiation on germination, seedling height and survival rate of two sesame (Sesamum indicum L.) cultivars from Senegal were investigated. Seeds of the extensively grown cultivars in Senegal, "32-15" and "38-1-7", were irradiated with 0, 100, 200, 300, 400, 500, 600, 700 and 800 Gy. The irradiated seeds (0, 300 and 400 Gy) of a Turkish cultivar "Birkan" were also used as a reference. Irradiated seeds were sown with their respective controls both in field and greenhouse conditions to assess germination rate, seedling height and survival rate as affected by the different doses of gamma rays. Germination, seedling height and survival rate significantly decreased with increasing irradiation dose. The depressive effect of radiation on germination was more pronounced in the field than in the greenhouse conditions. Cultivar "32-15" was more sensitive to gamma irradiation than cultivar "38-1-7". The effective dose which caused 50 % growth reduction was 645 Gy for variety "32-15" and 740 Gy for variety "38-1-7". The lethal dose (LD(50)) determined at 50 days after sowing was 550 Gy and 740 Gy for "32-15" and "38-1-7", respectively. From the parameters studied, seedling height reduction or LD(50) can equally be used in determining effective dose suitable for inducing artificial mutations

DESARROLLO DE VARIEDADES MULTILÍNEA DE CAUPÍ ADAPTADAS A SISTEMAS DE CULTIVO LOCALES Y OBJETIVOS DE PRODUCCIÓN ESPECÍFICOS DE AGRICULTORES MEDIANTE MEJORAMIENTO PARTICIPATIVO

International audienceBackground. Decentralized participatory breeding approach facilitate the development of varieties better suited for a diversity of farmers' contexts. To enhance breeding efficiency, formal methodological settings are needed to include, at early stage of selection, particular local practices and farmers' preferences. Objective. Evaluate how location, farmers' profile and local cropping system could be taken into account to optimize selection of cowpea varieties in a decentralized context. Methodology. Twenty-two candidate multiline varieties of cowpea (Vigna unguiculata L. Walp) were developed from a biparental family of recombinant inbred lines. These varieties were subjected to selection under edaphic and climatic conditions of three locations and two cropping systems (intercropping versus sole cropping). Trials were carried out in collaboration with farmers' federations. Participatory evaluations were conducted over two years by the three groups of farmers defined by the following production goals: grains production as priority ("Grain priority profile"), fodder as priority ("Fodder priority profile") and grain quality as priority ("Food processing priority profile"). Results. The statistical analysis supported significant effects of location and cropping system on the agronomic traits, with interactions effects involving the variety. A strong correlation was observed between the varietal choices of the two farmers' profiles which prioritized respectively grain and food processing. These farmers preferred varieties with higher grain yield and best grain quality. Farmers who prioritized fodder preferred more specific varieties, characterized by highest haulm yield. Implications. The clustering of farmers into specific profiles is an efficient method which allow expressing their diversified production goals through participatory evaluation. This led to more specific varietal choices for each of the profiles. Conclusion. This study set cropping systems and farmer profiles as formal design factors at early breeding stage. These factors acted efficiently to support the process of varietal choice.Antecedentes. El enfoque participativo y descentralizado del fitomejoramiento facilita el desarrollo de variedades mejor adaptadas a diversos contextos de los agricultores. Para mejorar la eficacia del fitomejoramiento es necesario establecer marcos metodológicos formales que incluyan, en las primeras fases de la selección, prácticas locales específicas y preferencias de los agricultores. Objetivo. Evaluar la ubicación, perfil de agricultores y sistema de cultivo local podrían tenerse en cuenta para optimizar la selección de variedades de caupí en un contexto descentralizado. Metodología. Se desarrollaron 22 variedades candidatas multilínea de caupí (Vigna unguiculata L. Walp) a partir de una familia biparental de líneas endógamas recombinantes. Estas variedades se sometieron a selección en condiciones edáficas y climáticas de tres localidades y dos sistemas de cultivo (cultivo intercalado frente a monocultivo). Los ensayos se llevaron a cabo en colaboración con federaciones de agricultores. Durante dos años se realizaron evaluaciones participativas de tres grupos de agricultores definidos por los siguientes objetivos de producción: producción prioritaria de cereales, producción prioritaria de forraje y calidad prioritaria del grano. Resultados. El análisis estadístico mostró efectos significativos en la localización y el sistema de cultivo en caracteres agronómicos, y con efectos de interacción con la variedad. Se observó una fuerte correlación entre las elecciones varietales de los dos perfiles de agricultores que priorizaban el grano y la transformación alimentaria. Estos agricultores prefirieron variedades con mayor rendimiento de grano y mejor calidad de grano. Los agricultores que priorizaron el forraje prefirieron variedades más específicas, caracterizadas por un mayor rendimiento. Implicaciones. La agrupación de los agricultores en perfiles específicos es un método eficaz que permite expresar sus objetivos de producción diversificados a través de la evaluación participativa. Esto permitirá realizar elecciones varie dades más específicas para cada uno de los perfiles. Conclusiones. Se establecieron los sistemas de cultivo y los perfiles de los agricultores como factores formales de diseño en la fase inicial de selección. Estos factores actuaron eficazmente para apoyar el proceso de elección varietal. El enfoque participativo resalta la congruencia y complementariedad entre los conocimientos de los agricultores es investigadores. Lo que permitió identificar, para los sistemas de cultivo intercalado y monocultivo, las variedades más adecuadas preferidas por cada uno de los tres grupos de agricultores