Impact of salinity on the production of tomato along the coastal areas of Benin Republic

The coast of Benin lies on a wide bay in the Gulf of Guinea called the Bight of Benin, about 125 km  between Togo and Nigeria. The coastal areas of Benin cover part of the cultivable lands of the country. A  total of 15 tomato varieties were recorded in the areas of study. The characteristics of each variety grown  under salinity were also recorded based on the assessment of farmers. Salinity causes unfavorable  conditions that restrain the normal crop production. The factors that contribute significantly to salinity were  soil salinity, wet breeze from high tide especially between June to August and direct watering of crop with  saline water. The wetted foliage of growing tomato absorbed the salts directly. The results obtained also  show that salinity in the coastal areas of Benin affected tomato growth, leaf length, and number of leaves,  which reduced yields and in severe cases, total yield was lost. Two varieties (aclinkon and petomèche)  seemed to be tolerant to salinity because of their average yield. Due to the heavy losses in tomato  production, producers were eager to be supplied with new varieties tolerant to salinity. Henceforth, it was  imperative to have an evaluation of the coastal areas of Benin affected by the salinity.Key words: Coastal areas, tomato production, salinity, wet breeze, high tide

Variation in the phytochemical composition of Chromolaena odorata (L.) King and Robinson (Asteraceae) across climatic zones in Benin (West Africa)

Chromolaena odorata (L.) King and Robinson (Asteraceae) is a tropical shrub with interesting chemical potential widely used in agriculture and medical science and which can be affected by several geographic and climatic conditions. Therefore, we investigated the phytochemical composition of this plant across climatic zones in Benin. The plant material collected from different locations was phytochemically screened by staining and precipitation tests. The total phenolic, flavonoid and tannin contents were determined using, the colorimetric method of Folin-Ciocalteu, the method of aluminum chloride and the method of vanillin, respectively, then the obtained data were subjected to analysis of variance. The phytochemical analysis revealed the presence of the main chemical groups such as alkaloids, free anthracene, coumarins, flavonoids, mucilage, tannins, reducing compounds, saponins, quinone derivatives, steroids. There was a significant difference (P < 0.05) in the phytochemical contents across geographical sites. In comparing the levels of phytochemicals among geographical locations, the raw material collected from the north climatic zone contained the highest phenolic and flavonoid contents, 147.59 ± 3.04 mg/g and 17.17 ±0.31 mg/g, respectively, compared to others. Overall, the study highlighted the potential of C. odorata as source of natural products. There was no difference in the phytochemical markers whereas the phytochemical contents vary across climatic zones. These results can be of use in the development of biopesticides from the raw material of C. odorata

Facteurs de développement des plantes invasives dans les systèmes agricoles au Bénin et implications pour une gestion durable

The periodic outbreak of invasive plants is one of the problems the West African agroecosystems, especially Beninese, are faced. The objective of this review is to analyze the approaches and the results of studies obtained on several models of invasive plants in Benin with an emphasis on the factors that favor their establishment in agricultural environments. From the evaluation of the bioecological adaptation potential of invasive plants, it resulted that there are intrinsic and extrinsic factors of distribution of invasive exotic species. The intrinsic factors are linked to the genetic and biological potential of plants while these extrinsic ones relate to anthropogenic actions and environmental conditions. The biology of invasive species, the anthropogenic actions and climate are the key factors of success in biological invasions. Improvement in agricultural systems and prediction models of infestation linked to climate change can, among other things, help limit resurgence’s impacts. Key words: Exotic invasive species, weed, agriculture, climate, BeninLa résurgence des plantes invasives est l’un des problèmes des systèmes agricoles en Afrique Sub-Saharienne, notamment au Bénin. Il est important de porter un regard analytique sur les causes des invasions de plantes en agriculture, pour une meilleure orientation dans le choix des moyens de lutte. Cette revue a pour objectif d’analyser les approches et résultats d’études obtenus sur plusieurs plantes invasives au Bénin, en ressortant les facteurs qui favorisent leur distribution dans les milieux agricoles. Il se dégage, à partir de l’évaluation du potentiel bioécologique d’adaptation des plantes invasives, qu’il y a des facteurs intrinsèques et extrinsèques qui concourent à leur distribution dans les systèmes agricoles. Les facteurs intrinsèques sont liés aux potentiels génétiques et biologiques des plantes invasives tandis que ceux extrinsèques se rapportent pour la plupart aux actions anthropiques et aux conditions environnementales du milieu. La biologie des plantes invasives, les actions anthropiques et le climat sont les facteurs clés de succès des invasions biologiques végétales. L’amélioration des systèmes de cultures, et les prédictions des infestations en lien avec le changement climatique peuvent entre autres aider à limiter les chocs de résurgence des plantes invasives dans les systèmes agricoles. Mots clés: Espèces exotiques envahissantes, mauvaises herbes, agriculture, climat, Béni

Diallel analysis of cowpea (Vigna unguiculata (L.) Walp.) genotypes under water deficit stress

Abstract Combining ability is referred to as the hybridization value of the parental genotypes involved in the crossing to develop hybrids. The best parents are selected through combining ability methods and subsequently used to produce high yielding and resistant hybrids. Thus, the objectives of this study were to (i) understand the nature and action of genes controlling water deficit tolerance, and (ii) identify superior genotypes from the genetic breadth provided by hybridization in cowpea. Twenty-four genotypes were subjected to normal irrigation and water deficit condition to examine combining ability, genotypic and phenotypic correlations for traits directly related to water deficit (proline and chlorophylls), grain yield and yield components. The results showed the presence of the action of additive and non-additive genes under both water regime conditions. However, there was the predominance of the action of additive genes for most of the traits studied under both conditions. The parents KVX61-1, IT06K242-3, IT07K-211–1-8, Kpodjiguèguè, IT99K-573–1-1, Tawa and IT97K-206–1-1 were observed to be good general combiners for proline content, chlorophyll content and traits associated with yield, while KVX61-1 × KVX396-18, IT06K242-3 × KVX396-18, IT07K-211–1-1 × KVX396-18, Kpodjiguèguè x KVX396-18, KVX61 -1 × IT97K-206–1-1, IT06K242-3 × IT97K-206–1-1, IT07K-211–1-1 × IT97K-206–1-1 and Kpodjiguèguè x IT97K-206–1-1 were proven to be the best specific combiners for traits directly related to water deficit tolerance and yield. It should be noted that number of days to pod maturity, pod length, number of pods per plant and weight of hundred seeds were highly heritable traits in this study

Optimization of cashew (Anacardium occidentale L.) apple juice’s clarification process by using cassava and rice starch

Objective: This study aims to optimize cashew apple juice clarification by using cassava and rice starch.Materiel and methods: Effects of dose of cassava and rice starch, incubation time at 30°C on clarity of cashew apple juice were investigated. Parameters such as, tannins, phenols, colour, vitamin C contents of cashew apple juice were evaluated using response surface methodology (RSM) and the optimum condition for cashew apples juice clarification by using cassava and rice starch was determined.Results: The regressions analysis showed that cassava starch dose and clarification time significantly (P&lt;0.001) influence juice clarity, while only clarification time significantly (p&lt;0.05) influence juice clarity with rice starch. The increase of cassava starch and rice starch dose significantly (p&lt;0.05) decreases the tannins content. Cassava starch at 6.2 ml/l for 300 minutes decreased tannins content at 34.2% with visual clarity of 93.75%, while rice starch at 10 ml/l for 193 minutes decreased tannins content at 42.14% with visual clarity of 94.8%.Conclusion: cassava and rice starch behaviour during cashew apples juice clarification were not similar. Nevertheless, from the results of optimization, cassava and rice starch preparations appeared efficient clarifying agents for cashew apple juice. The use of these efficient and economic natural local clarifying agents could improve the valorization of cashew products in developing countries.Keywords: Cashew, clarification, starch, optimization, Response Surface Methodology

Rhamphicarpa fistulosa, a parasitic weed threatening rain-fed lowland rice production in sub-Saharan Africa – A case study from Benin

Expansion of the facultative parasitic plant Rhamphicarpa fistulosa as a weed of rain-fed lowland rice was studied in 2007 on a national level (Benin) by repeating a survey from 1998. Wider species’ distribution was investigated in 2008. Current and potential impact and management strategies were investigated through farmer surveys and pot experiments. Out of 36 cultivated inland valleys visited across Benin, eight were found to be infested with Rhamphicarpa. Out of nine inland valleys inspected in 1998, Rhamphicarpa was found in five in 2007, compared with only three in 1998. Farmers estimated Rhamphicarpa-inflicted yield losses could exceed 60% and indicated that heavily infested fields are abandoned. In a pot experiment with a wide infestation range, the popular cultivar Gambiaka, combining resistance with sensitivity, showed a mean relative yield loss (RYL) of 63%. Parasitic Rhamphicarpa biomass (PRB), the difference between the above-ground biomass produced with and without a host, was suggested as indicator for infection level of this facultative parasite and hence as a practical measure for host resistance. Genetic variation in resistance and tolerance levels was observed among rice cultivars, but fertilizer applications significantly reduced parasite numbers, biomass and effects, cancelling out such genotypic differences. Depending on the tolerance level of the cultivars, the PRB only accounted for 3.7–38.8% of the average parasite-inflicted host biomass reductions, indicating phytotoxic effects of Rhamphicarpa infection. R. fistulosa is an apparently increasing constraint to rain-fed lowland rice in Benin, threatening rice production in the wider region. The use of resistant and tolerant cultivars, combined with fertilizer applications could reduce Rhamphicarpa infections and mitigate negative effects on rice yields

Onion (Allium cepa L.) and Drought: Current Situation and Perspectives

Onions (Allium cepa L.) are the second most commonly produced and consumed vegetable worldwide due to their economic, nutritional, and medicinal benefits. However, drought hinders vegetative growth, lowers yields and bulb quality, reduces photosynthetic activity, and alters the onion plant’s metabolism. This review provides a summary of global research on the impact of drought on onions. It specifically seeks to shed light on aspects that remain unclear and generate research avenues. Relevant scientific articles were sourced from the AGORA database, Web of Science (WoS), and search engines such as Google Scholar, Scopus, MEDLINE/PubMed, and SCImago to achieve this objective. A total of 117 scientific articles and documents related to onion and drought were critically examined. The review revealed agromorphological, physiological, biochemical, and genomic studies depicting factors that contribute to drought tolerance in onion genotypes. However, there was little research on the physiological, biochemical, and genetic characteristics of drought tolerance in onions, which need to be deepened to establish its adaptation mechanisms. Understanding the mechanisms of onion response to water stress will contribute to fast-tracking the development of drought-tolerant genotypes and optimize onion production. Future research should be more focused on investigating onion drought tolerance mechanisms and structural and functional genomics and identifying genes responsible for onion drought tolerance