Influence of soil moisture stress on vegetative growth and root yield of some cassava genotypes for better selection strategy in screen house conditions and different agro-ecologies in Nigeria

Cassava is a vital staple crop for many African populations particularly in Nigeria. This study was conducted to determine the effect of soil moisture on the performance of selected 12 cassava genotypes that were evaluated for yield and related traits under three percentages of field capacity (75% – control, 50%, and 25%) in the screen house and field conditions in three agro-ecologies (Ibadan-Derived Savanna, Mokwa-Southern Guinea Savanna, and Zaria-Northern Guinea Savanna) and randomized complete block design was used. Data were collected on plant height, stem girth, number of nodes and leaves, shoot weight, stomata conductant, stay-green, fresh root weight, and dry matter percentage and were analyzed using descriptive statistics and ANOVA. Genotypes differed significantly across and within locations. The higher stress level (25% field capacity – F.C.) resulted in a more significant reduction in vegetative growth than the moderate stress level of 50% F.C.; moisture levels were uniform over time for plant height and stem girth. The response to moisture levels varied widely among genotypes, indicating that they experienced a higher stress condition. Genotypes IITA-TMS-IBA980581, IITA-TMS-IBA010040, and IITA-TMS-IBA010034 were identified with good drought tolerance. Integrating physiological research with breeding efforts will help in the selection of suitable varieties for release

Efficacite de l’hydroxyde de cuivre contre la nervation noire du chou (Brassica oleracea l.) Causee par la bacterie xanthomonas campestris pv. Campestris

Pour tester l’efficacité de l’hydroxyde de cuivre contre la nervation noire du chou, des expérimentations ont été conduites sur le site maraîcher de Houèto (commune d’Abomey-Calavi), au cours desgrande et petite saisons de pluies de l’année 2013. Le dispositif de bloc aléatoire complet dispersé à quatre répétitions et cinq traitements a été utilisé. Les parcelles témoins, traitées avec l’oxyde de cuivre 1 kg/ha et avec l’hydroxyde de cuivre aux doses de 2,25 kg/ha, 3 kg/ha et 4,5 kg/ha étaient les traitements à comparer. La sensibilité de Xanthomonas campestris pv. campestris (Xcc) à l’hydroxyde de cuivre, l’incidence et la sévérité de la nervation noire du chou étaient les paramètres évalués au cours des expérimentations. La bactérie Xcc a été positivement confirmée. Pendant la grande saison de pluies, la sévérité a été significativement faible dans les parcelles traitées avec l’hydroxyde de cuivre aux doses de 3 kg/ha (7,11 %) et 4,5 kg/ha (7,09 %). Par contre, en petite saison de pluies, la maladie s’était faiblement manifestée sur tout le site expérimental avec une sévérité inférieure à 0,05 %. L’incidence était aussi plus élevée au cours de la grande saison de pluies (79,6 % à 82,5 %) comparée à la petite saison de pluies (0,9 % à 1,6 %). Les doses de 3 kg/ha et 4,5 kg/ha d’hydroxyde de cuivre ont été les plus efficaces contre la nervation noire du chou.Mots clés : Nervation noire du chou, hydroxyde de cuivre, efficacité, Xanthomonas campestris pv. campestrisEnglish abstractEfficiency of copper hydroxide on cabbage (Brassica oleracea l.) Black rot caused by xanthomonas campestris pv. CampestrisTo test the efficiency of copper hydroxide against the cabbage black rot, trials were conducted on the garden site of Houeto village (Abomey-Calavi), during the big and the short rainy seasons in 2013. The randomized complete block design with four repetitions and five treatments have been used. Untreated control plot, plot treated with copper oxide at 1 kg/ha and plots treated with copper hydroxide at 2.25 kg/ha, 3 kg/ha and 4.5 kg/ha were the five considered treatments. The susceptibility of Xanthomonas campestris pv. campestris (Xcc) to the copper hydroxide, the incidence and the severity of cabbage black rot, were the evaluated parameters during the two trials. Xcc was positively confirmed. During the big rainy season, the severity was significantly low in plots treated with copper hydroxide at 3 kg/ha (7.11 %) and 4.5 kg/ha (7.09 %). While during the short rainy season, the disease was weak in the whole experimental site with a severity varying between 0.02 % and 0.03 %. The incidence was also high during the big rainy season (79.6 % to 82.5 %) and weak during to the short rainy season (0.9 % to 1.6 %). The doses of 3 kg/ha and 4.5 kg/ha of copper hydroxide were efficient on cabbage black rot.Key words : Cabbage black rot, copper hydroxide, efficiency, Xanthomonas campestris pv. campestri

Integrated pest management in vegetable production: a guide for extension workers in West Africa

Indigenous and exotic vegetables are central to most nutrition, food security and poverty reduction programmes around the world. However, in most of West Africa, the economic opportunities offered by vegetables are often undermined by production and trade constraints (i.e. pest damage, inappropriate pesticide usage, absence of environmental safeguard policies and/or stringent food safety standards). Extension workers and, in places, farmers groups and local community organizations, are working towards helping farmers to increase their yields in sustainable ways that create wealth and reduce the risks to productivity. All too often, extension workers do not know the cause of common pest problems in the crops they work with. Pest problems usually arise when the biological, ecological and sociological processes which underpin agriculture are disrupted. This guide helps to fill that information gap. It is one of many responses by the International Institute of Tropical Agriculture (IITA) which enables such workers to develop and use technologies. It focuses on accurate identification and better understanding of biodiversity in the development and application of Integrated Pest Management (IPM) options against vegetable pests. IPM is a knowledge-intensive approach to enhance profitability of agricultural systems, while minimizing threats to human health and the environment. The technical knowledge and skills in this guide can be used to look for, develop and apply effective vegetable IPM options. The IPM options outlined here are in harmony with the environment, sustainable, simple to apply, and cheap to maintain. The guide addresses IITA’s strategic aim of increasing the quality and usefulness of IPM research in support of reducing food security and poverty. It draws heavily on IITA’s experiences in Africa, with a particular emphasis on vegetable agroecosystems in Benin. Given the substantial economic costs of pest infestations in vegetable agroecosystems, the use of this guide in Africa is expected to improve incomes and overall agricultural productivity in the long-term. Peter Hartmann Director General International Institute of Tropical Agriculture March 2010 ForewordThis guide has been produced by the International Institute of Tropical Agriculture (IITA) and Institut National des Recherches Agricoles du Bénin (INRAB), Cotonou, Benin, with support from the CGIAR Systemwide Program on Integrated Pest Management (SP-IPM), to improve the quality and usefulness of pest management research. This publication was part funded by the ACP-EU Technical Centre for Agricultural and Rural Cooperation (CTA)

Effets des rhizobactéries PGPR sur le rendement et les teneurs en macroéléments du maïs sur sol ferralitique non dégradé au Sud-Bénin

L’objectif de l’étude est d’évaluer les effets de 15 rhizobactéries promotrices de croissance végétative (PGPR en Anglais) sur le rendement et l’état nutritionnel des plants de maïs sur sol ferralitique non dégradé du Sud-Bénin. Les semences de maïs ont été inoculées avec des concentrations microbiennes d’environ 108 UFC/ml. Les teneurs en azote, en phosphore et en potassium d’échantillons de plants de maïs ont été déterminées. Les valeurs de rendement du maïs ont été soumises à une analyse de la variance à deux facteurs. Les rhizobactéries Pseudomonas fluorescens ont induit le rendement de maïs le plus élevé, dépassant de 41,46% le rendement de maïs obtenu avec l’inoculation de P. putida et de 118,05% le rendement de maïs obtenu au niveau des plants non inoculés. Les rendements de maïs induits par P. putida et Azospirillium lipoferum sont supérieurs respectivement de 54,17% et de 26,39% au rendement obtenu au niveau des plants non inoculés. Les résultats obtenus augurent de la possibilité d’utiliser les rhizobactéries PGPR comme des engrais biologiques pour une production durable de maïs. Au Sud du Bénin, où la pression démographique est forte et la baisse de la fertilité des sols croissante, l’utilisation de méthodes biologiques pour accroître les récoltes est une solution incontournable.Mots clés: Rhyzobactéries, Rendement, Maïs, Sol ferralitique, Béni

Soil-based screening for iron toxicity tolerance in rice using pots

The objective of this study was to assess the reliability of pot-based screening method for iron (Fe) toxicity tolerance in rice using soils from hot spots. Five lowland rice varieties with known reaction to Fe toxicity were grown in pots in a screen house for three seasons. Fe-toxic soils from two hot spot fields – Edozighi, Nigeria and Niaouli, Benin were used and soil from Africa Rice Center (AfricaRice) experimental farm, Cotonou, Benin was included as control. Leaf bronzing score (LBS) was determined at different stages, and grain yield was determined at maturity. Heritability was estimated using data across the three seasons. High heritability was recorded for LBS and grain yield. Grain yield reduction in stress treatment relative to control varied from 15 to 56% depending on the variety and soil. Bao Thai, Suakoko 8, and WITA 4 had better performance under Fe toxicity in terms of LBS, yield and relative yield reduction, whereas Bouake 189 and IR64 had poorer performance. Grain yield and LBS were significantly correlated but negatively at 60 days after sowing (DAS). Overall, the results found in this experiment were consistent with previous field studies. Therefore, pot screening using soils from hot spots can be used by rice breeding programs to reliably assess Fe toxicity tolerance ex situ

Gestion intégrée des nuisibles en production maraîchère : Guide pour les agents de vulgarisation en Afrique de l'Ouest

Les parasites se manifestent généralement en cas de bouleversement des processus biologiques, écologiques et sociologiques qui sous-tendent l'agriculture. En plus d'apporter des informations sur la gestion durable des menaces biotiques portées à une production végétale saine, ce guide suggère également des manières d'enseigner et de diffuser des pratiques de lutte antiparasitaire intégrée auprès d'un public plus large. Exceptionnellement bien illustré par des illustrations, tableaux et photos, cet ouvrage se promet d'être une référence précieuse pour les professionnels sur le terrain, les agents de vulgarisation, les techniciens, les étudiants et les scientifiques

Screening African rice (Oryza glaberrima) for tolerance to abiotic stresses: I. Fe toxicity

AbstractIron (Fe) toxicity is recognized as one of the most widely spread soil constraints for rice production especially in West Africa. Oryza glaberrima the cultivated rice species that originated from West Africa is well-adapted to its growing ecologies. The aim of this study was to identify the promising O. glaberrima accessions tolerant to Fe toxicity from the 2106 accessions held at the AfricaRice gene bank. The screenings were conducted over a four-year period and involved evaluating the entries under Fe-toxic field conditions in West Africa, selecting good yielding accessions and repeating the testing with newly selected lines. Three accessions (TOG 7206, TOG 6218-B and TOG 7250-A) were higher yielding than O. sativa checks under stress but with similar yields under control conditions. These accessions yielded over 300g/m2 under both Fe toxicity and control conditions. In conclusion, these materials could be used as donors in breeding programs for developing high yielding rice varieties suited to Fe toxicity affected areas in West Africa

Re-assessing the pest status of Tetranychus evansi (Acari: Tetranychidae) on solanaceous crops and farmers control practices in Benin

Open Access Journal; Published online: 24 Sep 2022This study was carried out 7 years after a first one conducted in 2013 as part of the policy of the Benin government to promote the vegetable production sector. Data collection was mostly based on a countrywide survey conducted in 25 municipalities throughout Benin, from August to December 2020. Farmers were selected based on their experience in cultivating solanaceous crops, and were interviewed to assess their perception about the severity of the spider mite Tetranychus evansi, the control method they used against this pest, and their knowledge about potential predators associated with the mites. Additionally, predatory mites associated with T. evansi in farmer fields were identified. All farmers recognized T. evansi to which they attributed local names depending on their ethnic group. They were also able to identify its damages on solanaceous crops. They indicated that outbreaks of T. evansi occurs at the end of the rainy season while their damages are more severe during the dry season. Production losses due to the mites were estimated by farmers to 27%, 24% and 22% respectively for tomato, African eggplant, pepper in the moderate damage case and 80%, 79%, 55% respectively for tomato, African eggplant and pepper in the severe damage conditions. To fight the mites, farmers generally apply heavy doses of chemical pesticides at high frequency. Pyrethroid and organophosphate compounds are the most frequently used pesticides. The only phytophagous mite recorded was T. evansi. A total of four species of predatory mites, all belonging to the phytoseiid family, were found associated with the pest on Solanaceous plants: Amblyseius swirskii, A. tamatavensis, Neoseiulus barkeri and N. longispinosus. This is the first report of the presence of N. longispinosus in Benin. Considering the high losses attributed to the pest, effective and sustainable management practices are necessary

Diversity and distribution of whiteflies colonizing cassava in eastern Democratic Republic of Congo

Open Access Journal; Published online: 19 Sep 2022The present study characterizes Bemisia tabaci and Bemisia afer from cassava in eastern Democratic Republic of Congo (DRC). The Mitochondrial COI sequencing revealed the occurrence of six cassava B. tabaci mitotypes, which were designated into four haplogroups (SSA-ECA, SSA-CA, SSA2, and SSA-ESA) using KASP SNP genotyping. SSA-ECA (72%) was the most prevalent and occurred in the northern part of the surveyed area, in the Ituri and Nord/Sud-Kivu provinces, whilst SSA-CA (21%) was present in the south, primarily in Haut-Katanga. SSA-ECA was predominant in the areas of north-eastern DRC most severely affected by cassava brown streak disease and was also reported in the new outbreak area in Pweto territory, Haut-Katanga, in the south. Bemisia afer comprised two major clusters with 85.5% of samples in cluster one, while the rest were in cluster two, which has no reference sequence in GenBank. This study provides important information on the genetic diversity of B. tabaci and B. afer in eastern DRC. This knowledge will be used as a basis for further studies to understand and to identify the role of whitefly haplogroups, their population densities and consequences for virus epidemics and spread as well as leading to improved vector and virus management strategies

Multiple small-effect alleles of Indica origin enhance high iron-associated stress tolerance in rice under field conditions in west Africa

Open Access Journal; Published online: 15 Jan 2021Understanding the genetics of field-based tolerance to high iron-associated (HIA) stress in rice can accelerate the development of new varieties with enhanced yield performance in West African lowland ecosystems. To date, few field-based studies have been undertaken to rigorously evaluate rice yield performance under HIA stress conditions. In this study, two NERICA × O. sativa bi-parental rice populations and one O.sativa diversity panel consisting of 296 rice accessions were evaluated for grain yield and leaf bronzing symptoms over multiple years in four West African HIA stress and control sites. Mapping of these traits identified a large number of QTLs and single nucleotide polymorphisms (SNPs) associated with stress tolerance in the field. Favorable alleles associated with tolerance to high levels of iron in anaerobic rice soils were rare and almost exclusively derived from the indica subpopulation, including the most favorable alleles identified in NERICA varieties. These findings highlight the complex genetic architecture underlying rice response to HIA stress and suggest that a recurrent selection program focusing on an expanded indica genepool could be productively used in combination with genomic selection to increase the efficiency of selection in breeding programs designed to enhance tolerance to this prevalent abiotic stress in West Africa