Welcome to the International Institute of Tropical Agriculture Research Repository
Journal and Journal Articles: Recent submissions
Now showing items 1201-1220 of 5271
-
Economic impacts of fall armyworm and its management strategies: evidence from southern Ethiopia
(2020-09)This paper explores the economic implications of fall armyworm (FAW) and its management strategies by exploiting exogenous variation in FAW exposure amongst households in southern Ethiopia. We find that FAW exposure affects maize yield and sales negatively, but not consumption. Furthermore, we find evidence of crowding-in and intensification of insecticide use in response to FAW exposure. We also find suggestive evidence that existing extension service arrangements lack the capacity to deal with ... -
Appraisal and composition of some traditional complementary foods for infant nutrition in Sierra Leone
(2020)Malnutrition among infants in Sierra Leone still ranks one of the highest globally. Potency of some locally-formulated complementary food at resolving the problem had been proven. The experiment aimed at evaluating nutrient contents in traditional complementary foods consumed by infants in Eastern and Northern regions of Sierra Leone was carried out between 2016 and 2018. Ten common recipes identified through semi-structured questionnaire were standardized and analyzed using standard laboratory ... -
Comparative assessment of genetic diversity matrices and clustering methods in white Guinea yam (Dioscorea rotundata) based on morphological and molecular markers
(2020)Understanding the diversity and genetic relationships among and within crop germplasm is invaluable for genetic improvement. This study assessed genetic diversity in a panel of 173 D. rotundata accessions using joint analysis for 23 morphological traits and 136,429 SNP markers from the whole-genome resequencing platform. Various diversity matrices and clustering methods were evaluated for a comprehensive characterization of genetic diversity in white Guinea yam from West Africa at phenotypic and ... -
Combining ability of extra-early maize inbreds derived from a cross between maize and Zea diploperennis and hybrid performance under contrasting environments
(2020)Knowledge of the genetic mechanisms conditioning drought tolerance in maize is crucial to the success of hybrid breeding programs aimed at developing high-yielding cultivars under drought. The objectives of this study were to determine the combining ability of extra-early inbreds, compute the heritability of measured traits, assess the performance of inbreds in hybrid combinations and investigate the associations among traits under drought and optimal conditions. A total of 252 hybrids generated ... -
Physicochemical properties and total carotenoid content of high-quality unripe plantain flour from varieties of hybrid plantain cultivars
(2020)Unripe plantain has been considered as having commercial potential or used as an ingredient for other foods. Information on the physicochemical and carotenoid properties of flours from hybrid plantain cultivars in the literature is limited. This study was conducted to determine the physicochemical properties and carotenoid contents of unripe plantain flour from selected hybrid plantain cultivars using standard laboratory methods. The unripe plantain pulps of four varieties (PITA 26, PITA 27, Mbi ... -
Critical slope length for soil loss mitigation in maize-bean cropping systems in SW Kenya
(2020)Soil erosion and land fragmentation threaten agricultural production of sub-Saharan African highlands. At our study site in Western Kenya, farm size is mostly < 2 ha, laid out in narrow strips in slope direction and ploughed downhill. Soil conservation measures like hedgerows and green manures can reduce effective slope length for erosion, but compete with crops for space and labour. Knowledge of critical slope length can minimise interventions and trade–offs. Hence, a maize–bean intercrop (MzBn) ... -
Effect-directed profiling and identification of bioactive metabolites from field, in vitro -grown and acclimatized Musa spp. accessions using high-performance thin-layer chromatography-mass spectrometry
(2020-04-12)Bananas and plantains ( Musa spp.) are used as nutritious foods, and at the same time, are a source of phytoconstituents for the pharmaceutical industry. As biological activities of especially the pulp and peel of Musa spp. have been documented, this study investigated the variation in the secondary metabo- lite profiles of the leaves from field, in vitro -grown and acclimatized accessions. The genetic fidelity of the diverse accessions was assessed using diversity array technology sequencing. It ... -
Productivity, water- and nitrogen-use efficiency, and profitability of pearl millet (Pennisetum glaucum) under different nitrogen applications in semiarid region of Nigeria
(2020-08-27)An experiment was conducted to examine the performance of pearl millet under different nitrogen (N) fertilizer rates in two locations in the semiarid zone of Nigeria. The objective was to evaluate the effects of different N rates on pearl millet yields, water- and nitrogen-use efficiency, and profitability. Grain yield increased by 23, 26, 32, 32, and 27% and by 38, 41, 54, 58, and 56% compared to unfertilized plots when applying 20, 40, 60, 80, and 100 kg Nha−1 in Minjibir and Gambawa, respectively. ... -
The effect of traditional and improved solar drying methods on the sensory quality and nutritional composition of fruits: a case of mangoes and pineapples
(2020-06)Background This study investigated the effect of traditional and improved solar drying methods on the sensory quality and nutritional composition of the dried fruit products; using mangoes and pineapples, as a case study. The fruits were dried under five solar drying methods namely; open sun drying (OSD), black-cloth shade (BCS), white-cloth shade (WCS), a conventional solar dryer (CSD), and a newly improved solar dryer (ISD) technology. The ISD unit was made of a modified solar concentrator ... -
Evolutionary distance explains shade tree selection in agroforestry systems
(2020-12)Enhancing agrobiodiversity offers a suite of functions key to the sustainability of low input agroecosystems. The pairing of shade trees in pan-tropical tree-crop systems represents one of the most common and widespread applications of agroecosystem diversification, yet given the vastly heterogeneous conditions in which shade tree selection is made, generalizable advances in the identification of suitably paired tree-crop and shade tree is essential for performance and adoption. Here, we determine ... -
Science of scaling: understanding and guiding the scaling of innovation for societal outcomes
(2020-09)This Editorial to the Special Issue “Science of Scaling: connecting the pathways of agricultural research and development for improved food, income and nutrition security” presents the framing, overview and analysis of 10 articles focussed on scaling innovation in the agricultural research for development sector. The publications cut across three categories that focus on: (i) Understanding the scaling trajectory retrospectively from a longer term, systems perspective, (ii) Understanding scaling ... -
Bioactivity of essential oils of Cymbopogon citratus (DC) Stapf and Cymbopogon nardus (L.) W. Watson from Benin against Dinoderus porcellus Lesne (Coleoptera: Bostrichidae) infesting yam chips
(2020-08-18)Dinoderus porcellus L. (Coleoptera: Bostrichidae) is a most abundant and damageable pest of stored yam chips in West Africa. In view of the negative effects related to the use of synthetic chemical insecticide, it is important to develop alternative eco-friendly methods of control, such as the use of plant essential oils. The chemical composition and biological effects (repellent, antifeedant, contact and fumigant toxicity) of essential oils from Cymbopogon citratus (DC) Stapf and Cymbopogon nardus ... -
Modeling planting-date effects on intermediate-maturing maize in contrasting environments in the Nigerian savanna: an application of DSSAT model
(2020-06)The Crop Environment Resource Synthesis (CERES)-Maize model in Decision Support System for Agricultural Technology Transfer (DSSAT) was calibrated and evaluated with experimental data for simulation of response of two intermediate-maturing maize varieties to different sowing dates in the Nigerian savannas. The calibration experiments involved 14 consecutive field trials conducted in the rainy and dry seasons in Bayero University Kano (BUK), Dambatta, and Zaria between 2014–2019. Two sets of field ... -
Canopy cover evolution, diurnal patterns and leaf area index relationships in a Mchare and Cavendish banana cultivar under different soil moisture regimes
(2020-10)The biggest abiotic threat to banana (Musa spp.) production is water deficit, but physiological indicators in plantations are lacking. Canopy Cover (CC) seems to be a relevant parameter, but so far not used in banana fields. Field experiments were conducted to determine the effect of optimal irrigation (FI) versus rainfed (RF) on CC and Leaf Area Indices (LAI) in two experiments with different cultivars (Mchare ‘Huti Green’ [HG, AA] and Cavendish ‘Grand Naine’[GN, AAA]) (n = 3 for HG, n = 4 for ... -
Melanization of eggs and larvae of the parasitoid, Epidinocarsis lopezi (Hymenoptera: Encyrtidae), by the cassava mealybug, Phenacoccus manihoti (Homoptera:Pseudococcidae)
(1988)The encyrtid wasp Epidinocarsis lopezi (De Santis) has been introduced into Africa as a biological control agent against the cassava mealybug Phenacoccus manihoti Matile-Ferrero. This host has a defense reaction against the immature parasitoid that involves encapsulation and melanization. Under laboratory conditions, 37.5% of once-stung cassava mealybugs had been parasitized, as indicated by eggs and larvae of the parasitoid in dissected hosts. Of these parasitized cassava mealybugs, 89.6% contained ... -
Changes in the composition of the fauna associated with the cassava mealybug, Phenacoccus manihoti, following the introduction of the parasitoid Epidinocarsis lopezi
(1987-12)Over 130 species of insects were found in association with the cassava mealybug (CM), Phenacoccus manihoti, and its newly introduced parasitoid Epidinocarsis lopezi in Africa. As the CM in SW Nigeria declined under the influence of E. lopezi, this introduced wasp maintained densities of 2.8-3 per CM-infested tip early in the dry season and 1.3-1.6 per infested tip late in the dry season, but declined overall from 1.3 to 0.2 per randomly collected tip within 1 year. The decline of CM led to a sharp ... -
Introduction and dispersal of Epidinocarsis lopezi (Hym., Encyrtidae), an exotic parasitoid of the cassava mealybug, Phenacoccus manihoti (Hom., Pseudococcidae), in Africa
(1987-06)In 1981 the South American parasitoid Epidinocarsis lopezi (DeSantis) was imported into Nigeria for control of the cassava mealybug, Phenacoccus manihoti Mat.-Ferr. It was multiplied in an insectary at the International Institute of Tropical Agriculture (IITA), Ibadan, and first released in 1981/82. Within 3 years it dispersed over 200 000 km2 in southwestern Nigeria, occupying between 70 and 98% of all fields. By December 1985, a total of over 50 releases in 34 regions had been made in 12 African ... -
Impact of the exotic parasitoid Epidinocarsis lopezi on cassava mealybug (Phenacoccus manihoti) populations
(1987-12)Epidinocarsis lopezi an exotic parasitoid to Africa, was first released to control the cassava mealybug (CM), Phenacoccus manihoti, at IITA (Ibadan) in November 1981, and a year later at Abeokuta, both in southwestern Nigeria. Population dynamics study of CM and its natural enemies was conducted for 4 years. CM population peaks usually occurred during the second half of the dry season (January-April). E. lopezi was the only natural enemy that was found during the whole year and in high densities. ...
