Analyse de la variabilite des rendements du riz selon les varietes et les pratiques culturales\ua0: Cas des perimetres irrigues de Toula, Bonfeba et de Diomona au Niger

Rice ( Oryza sativa L.) is very important in Niger for its contribution to improve food security and people\u2019s incomes. Despite the existence of several potentialities (irrigable potential, creation of several irrigated perimeters); Niger is still dependent on imports to meet its rice consumption requirements. Unfortunately, yields have stagnated. The objective of this study was to determine the factors that induce yield differentials between rice varieties based on the producers\u2019 cultural practices. The study was carried out in the Tillab\ue9ri region of Niger, on three irrigated perimeters, with a sample of 50 producers in 5 villages. The study was based on a survey with a questionnaire integrated into a Smartphone, and observation based on the demarcation of plots and subplots in the producers fields. Results obtained showed that the management of the crop was variable and spatially not only from one perimeter from one producer to another. Significant reductions in yield differentials of 53 to 22% were obtained based on the variety and applied herbicide dose.\ua0La riziculture ( Oryza sativa L.) est une activit\ue9 tr\ue8s importante au Niger pour sa contribution \ue0 l\u2019am\ue9lioration de la s\ue9curit\ue9 alimentaire et des revenus des populations. Cependant, malgr\ue9 l\u2019existence de plusieurs potentialit\ue9s (potentiel irrigable, cr\ue9ation de plusieurs p\ue9rim\ue8tres irrigu\ue9s), les nig\ue9riens continuent \ue0 \ueatre d\ue9pendants du riz en provenance de l\u2019ext\ue9rieur. Parmi les difficult\ue9s que rencontre la production rizicole, la principale reste la stagnation des rendements. C\u2019est pour comprendre les causes qui sont \ue0 la base de cette stagnation que cette \ue9tude a \ue9t\ue9 men\ue9e. L\u2019objectif principal vis\ue9 est de d\ue9terminer les facteurs induisant les \ue9carts de rendements entre les vari\ue9t\ue9s de riz selon les pratiques culturales des producteurs. L\u2019\ue9tude s\u2019est d\ue9roul\ue9e dans la r\ue9gion de Tillab\ue9ri, sur trois am\ue9nagements hydro-agricoles avec un \ue9chantillon de 50 producteurs repartis dans 5 villages. Pour atteindre cet objectif, l\u2019\ue9tude s\u2019est bas\ue9e sur une phase d\u2019enqu\ueate bas\ue9e sur un questionnaire int\ue9gr\ue9 dans un Smartphone, et une autre phase d\u2019observation, bas\ue9e sur la mise en place des placettes et sous-placettes dans les champs des producteurs afin de recueillir les informations sur les pratiques culturales du riz et d\u2019\ue9valuer les rendements obtenus. Les r\ue9sultats obtenus ont montr\ue9 que la gestion de la culture de riz est variable non seulement d\u2019un p\ue9rim\ue8tre \ue0 un autre, mais aussi d\u2019un producteur \ue0 un autre, avec des cons\ue9quences sur le rendement. Des r\ue9ductions importantes des \ue9carts de rendement de 53 \ue0 22 % ont \ue9t\ue9 obtenues en fonction de la vari\ue9t\ue9, de la dose d\u2019herbicide appliqu\ue9e et le non-respect des \ue2ges des plants au repiquage

Okra (Abelmoschus spp.) in West and Central Africa: Potential and progress on its improvement

Okra (Abelmoschus spp.) is a traditional vegetable crop with considerable area under cultivation in Africa and Asia with huge socio-economic potential in West and Central Africa. It has been called “a perfect villager’s vegetable” because of its robust nature, dietary fibers and distinct seed protein balanced in both lysine and tryptophan amino acids (unlike the proteins of cereals and pulses) it provides. However, okra has been considered a minor crop and no attention was paid to its improvement in the international research program in past. This review describes a general overview of okra’s nutritional and economic potential with special reference to its past and recent progress on germplasm regeneration, genetic studies and efforts on genetic improvement in West and Central Africa

Okra (Abelmoschus spp.) in West and Central Africa: Potential and progress on its improvement

Okra (Abelmoschus spp.) is a traditional vegetable crop with considerable area under cultivation in Africa and Asia with huge socio-economic potential in West and Central Africa. It has been called “a perfect villager’s vegetable” because of its robust nature, dietary fibers and distinct seed protein balanced in both lysine and tryptophan amino acids (unlike the proteins of cereals and pulses) it provides. However, okra has been considered a minor crop and no attention was paid to its improvement in the international research program in past. This review describes a general overview of okra’s nutritional and economic potential with special reference to its past and recent progress on germplasm regeneration, genetic studies and efforts on genetic improvement in West and Central Africa

NORMES TECHNIQUES ET PRATIQUES LOCALES DES PRODUCTEURS DANS LES PERIMETRES RIZICOLES IRRIGUES DE TOULA ET DE BONFEBA AU NIGER

In Niger, rice cultivation contributes significantly to the food security of populations. The various investments made by the country have made it possible to promote irrigated rice growing in the valley of the river with two crops of rice per year and thus to increase production significantly But it is clear that the technical standards that are supposed to be applied to irrigated rice areas have undergone changes over the years, thus reducing the expected performance of this modern rice crop. The objective of this study was to analyse the evolution of technical standards of rice production and local practices in irrigated areas. The study was carried out on two irrigated rice-producing sites in Niger and was based on survey involving key informants. The results showed that there was a great diversity between technical standards and practices in the fields. In addition to the approved varieties, the choice of producers also covered Community varieties, whereas this practice is prohibited on irrigated areas. Transplanting did not meet the standard of 25 pockets per m\ub2. The herbicide doses used by the producers varied from 80 to 240 g ha-1\ua0; while the recommended one was 80 g ha-1. Mineral fertilisation was different from the prescribed standards ; not only in terms of quantity but also in terms of application frequency. These under performances are due to the inefficiency of technical management which does not reach the greatest number of producers. Technical supervision lacks technical and material resources and is still based on traditional methods for disseminating agricultural advice. The methods applied today are outdated. It would, therefore, be necessary to revise the farm council\u2019s dissemination methods.Au Niger, la riziculture contribue pour beaucoup dans la s\ue9curit\ue9 alimentaire des populations. Les diff\ue9rents investissements effectu\ue9s par le pays ont permis de promouvoir la riziculture irrigu\ue9e dans la vall\ue9e du fleuve avec deux r\ue9coltes de riz par an et donc d\u2019augmenter significativement les productions. Mais, force et de constater que les normes techniques cens\ue9es \ueatre en application sur les p\ue9rim\ue8tres rizicoles irrigu\ue9s ont subi des changements au fil des ann\ue9es r\ue9duisant, ainsi, les performances esp\ue9r\ue9es de cette riziculture moderne. La pr\ue9sente \ue9tude avait pour objectif d\u2019analyser l\u2019\ue9volution des normes techniques de la production du riz et les pratiques locales dans les p\ue9rim\ue8tres irrigu\ue9s. L\u2019\ue9tude s\u2019est d\ue9roul\ue9e sur deux p\ue9rim\ue8tres rizicoles irrigu\ue9s au Niger et s\u2019est bas\ue9e sur des enqu\ueates aupr\ue8s d\u2019informateurs cl\ue9s. Les enqu\ueates se sont bas\ue9es sur un guide-questionnaire o\uf9 il s\u2019agit pour l\u2019informateur-cl\ue9 de r\ue9pondre \ue0 diff\ue9rentes questions en rapport avec les pratiques agricoles li\ue9es \ue0 la culture du riz dans les p\ue9rim\ue8tres rizicoles irrigu\ue9s. L\u2019analyse des donn\ue9es a \ue9t\ue9 effectu\ue9e en utilisant les logiciels Excel, R Commender et le logiciel Nvivo. Les r\ue9sultats obtenus ont montr\ue9 qu\u2019il y a une grande diversit\ue9 entre les normes techniques et les pratiques sur le terrain. En plus des vari\ue9t\ue9s homologu\ue9es, le choix des producteurs a port\ue9 aussi sur les vari\ue9t\ue9s appel\ue9es communautaires alors que les r\ue8gles l\u2019ont interdit sur les p\ue9rim\ue8tres irrigu\ue9s. Les repiquages n\u2019ont pas respect\ue9 la norme qui \ue9tait de 25 poquets par m\ub2. Les doses d\u2019herbicide apport\ue9es par les producteurs ont vari\ue9 de 80 \ue0 240 g ha-1 alors que la dose recommand\ue9e \ue9tait de 80 g ha-1. La fertilisation min\ue9rale \ue9taitloin des normes prescrites non seulement en termes de quantit\ue9 mais aussi en termes de fr\ue9quence d\u2019application. Ces sous performances sont dues \ue0 l\u2019inefficience de l\u2019encadrement technique qui n\u2019arrive pas \ue0 toucher le plus grand nombre de producteurs. L\u2019encadrement technique manque de moyens tant mat\ue9riel que technique et se base encore sur des m\ue9thodes traditionnelles pour diffuser le conseil agricole. Les m\ue9thodes appliqu\ue9es aujourd\u2019hui sont d\ue9pass\ue9es. Il serait donc n\ue9cessaire que les m\ue9thodes de diffusion du conseil agricole soient r\ue9vis\ue9es. L\u2019utilisation des nouvelles technologies de l\u2019information et de la communication peut \ueatre une bonne opportunit\ue9 pour une diffusion efficace du conseil agricole

Plant-parasitic nematode communities associated with Moringa tree (Moringa oleifera Lam.) in western Niger

Moringa (Moringa oleifera Lam) is a crop that is becoming more and more important in Niger, but very little attention has been devoted to its pest problems. Nematode fauna survey was undertaken in three important Moringa producing sites in western Niger. Soil and roots samples were taken from the plant’s rhizosphere at 20-30-cm deep. Nematological analysis of these samples revealed the presence of 11 genera of plant-parasitic nematodes among which the most frequent and abundant were Meloidogyne spp., Helicotylenchus spp. and Hoplolaimus spp. The average prominence values of these three nematodes were 236.69, 105.25 and 97.93, respectively. In roots, Meloidogyne spp. alone represented up to 90% of the plant-parasitic nematode communities. Its average prominent value was 591.46.

Evolution des populations des champignons endomycorhiziens sur les adventices de quatre sites maraîchers de la région de Maradi au Niger

Le rôle important que jouent les endomycorhizes dans l’amélioration de la nutrition minérale et la protection des plantes est aujourd’hui largement reconnue. Cependant dans des pays comme le Niger, peu de travaux leur ont été consacrés. Cette étude a été conduite pour évaluer la mycorhization dans les parcelles de poivron pendant la contre-saison afin de connaitre le moment opportun de les récupérer dans le but de les utiliser ultérieurement dans des programmes de développement des cultures maraichères. Des échantillons de sol et de racines ont été prélevés dans 4 sites sur les 9 principales adventices du poivron. Ils ont été analysés au laboratoire et la densité des spores et l’intensité de l’infection ont été déterminées. Ces deux paramètres ont varié d’un site à l’autre et d’une plante à l’autre. Cinq espèces d’endomycorhizes à vésicules et arbuscules ont été identifiées dont 3 appartenant au genre  Glomus et 2 au genre Gigaspora. Acanthospermum hispidum et Solanum nigrum ont été les plantes les plus infectées. Sur les 6 mois de l’étude, les plus fortes densités de spores et d’intensité d’infection ont été enregistrées entre décembre et janvier et les plus faibles en mars.Mots clés : Endomycorhizes, dynamiques des populations, cultures maraichères, Niger

Insecticidal effect of Jatropha curcas oil on the aphid Aphis fabae (Hemiptera: Aphididae) and on the main insect pests associated with cowpeas (Vigna unguiculata) in Niger

The insecticidal activity of Jatropha curcas has been evaluated on various crop pests. Oil concentrations of 0.5, 1, 2.5, 5, 10 and 15% were first tested on the black bean aphid (Aphis fabae Scop.) as part of an efficacy test conducted in the laboratory. During a second stage, the insecticidal efficacy of 5 and 7.5% oil concentrations was evaluated on the main pests infesting cowpea crops (Vigna unguiculata L.) as part of a field test conducted at the University of Niamey (Niger). The results obtained in the two tests demonstrate the biocidal effect of the treatments applied, which increases with the concentration. On the black bean aphid, the biocidal effect increases during the hours following the application of oil before reaching a peak after 4 days. On cowpeas, J. curcas oil concentrations of 5% and 7.5% make it possible to reduce the level of attack by aphids (Aphis craccivora) by 10 and 50% respectively compared to the control. A 50% and 75% fall in the number of thrips (Megalurothrips sjöstedti) and bugs (Anoplocnemis curvipes), respectively, can be observed under the same conditions. This treatment made it possible to greatly increase yields compared to the untreated control

Existence of Several Pathotypes among Rice Yellow Mottle Virus (RYMV) Isolates Collected in Niger Republic

This study has been conducted in screen house with an aim to asses the Rice yellow mottle virus pathogenic diversity and the level of resistance of released varieties in Niger republic. Sixty RYMV isolates from 23 Niger rice perimeters were inoculated mechanically to nine rice cultivars. The disease symptoms were scored at 42 days after inoculation. Analysis of Variance (ANOVA) and Additive Main effect and Multiplicative Interaction (AMMI) analysis were performed on the percentage of severity. The reaction of the rice cultivars to the virus isolates was significantly different. The interaction between isolates and rice cultivars was also significant. AMMI cluster analysis revealed the existence of four major pathotypes (Path 1 to 4) of Rice Yellow Mottle Virus (RYMV) in Niger republic. Path 4 pathotype included 12 resistance breaking isolates (20%). Path 3 and Path 2 pathotypes consist of 15 and 26 isolates respectively and were typical of wild type isolates with moderate level of pathogeny, including none aggressive (path 3 = MP) and aggressive isolates (Path 2 = MPA). The fourth pathotype Path 1 was made of 7 isolates and typical of particular isolates which have a moderate pathogenic level (FP). Resistance Breaking (RB) isolates occupied 30% of Niger rice ecologies in variable proportion. The rice varieties (Bassiroumo, IR15-29-690-3-1 and Kassoumo) released in Niger were highly susceptible to RYMV and therefore constituted a favorable condition for the rice yellow mottle disease propagation. This information is useful in rice breeding programs in the development and deployment of RYMV resistant cultivars to different rice perimeters in Niger Republic

Effectiveness of two biopesticides against the invasive tomato pest Tuta absoluta

International audienceTuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is among the most devastating pests worldwide of solanaceous plants, particularly of tomato (Solanum lycopersicum L.). Since its recent introduction into sub-Saharan Africa, it has become an additional widespread tomato pest throughout the region. When no control measures are taken, yield losses caused by T. absoluta larvae can reach 100%. Chemical control remains the primary management option despite its many adverse effects and increasing inefficiency due to the species' endophytic habits and ability to develop insecticide resistance. Safer and more effective alternatives are therefore urgently required. Here, we investigated the effectiveness of two bioinsecticides compared to that of a widely used deltamethrin-based synthetic insecticide, in preventing damage caused by T. absoluta larvae to tomato leaves and fruits, thereby affecting tomato yield. A field trial was conducted in 2018 and 2019 in northwestern Senegal using a randomized complete block design. Damage caused by T. absoluta affected approximately 65% of total leaf area and 3-24% of the fruits. Damage to the leaves caused by other insect species or other factors was less significant. At the dose applied, the chemical insecticide did not significantly reduce the surface area of leaflets affected by T. absoluta or other causal agents, the number of T. absoluta mines on the leaflets, or the proportion of fruits damaged. In contrast, the azadirachtin and Bacillus thuringiensis (Bt) formulations rapidly and significantly reduced damage to both leaves and fruits. The proportion of fruits damaged was reduced by a factor two and the total tomato yield was improved, particularly when the Bt formulation was used. In addition to their effectiveness in reducing damage caused by T. absoluta larvae to tomato leaves and fruit, and increasing the yield of marketable fruits, the viability of these organic alternatives was shown. The scope of our results is discussed in the context of T. absoluta control, in particular in integrated pest management programmes for tomato crops