Food quality profile of pounded yam and implications for yam breeding

Open Access ArticleBACKGROUND Assessment of the key preferred quality traits in pounded yam, a popularly consumed yam food product in West Africa, is often done through sensory evaluation. Such assessment is time-consuming and results may be biased. Therefore, there is a need to develop objective, high-throughput methods to predict the quality of consumer-preferred traits in pounded yam. This study focused on how key quality traits in pounded yam proposed to yam breeders were determined, measured by biophysical and biochemical methods, in order to shorten the breeding selection cycle through adoption of these methods by breeders. RESULTS Consumer tests and sensory quantitative descriptive analysis (QDA) validated that preferred priority quality traits in pounded yam were related to textural quality (smooth, stretchable, moldable, slightly sticky and moderately hard) and color (white, cream or light yellow). There were significant correlations between sensory textural quality attributes cohesiveness/moldability, hardness, and adhesiveness/stickiness, with textural quality measurements from instrumental texture profile analysis (TPA). Color measurement parameters (L*, a*, and b*) with chromameter agreed with that of sensory evaluation and can replace the sensory panel approach. The smoothness (R2 = 1.00), stickiness (R2 = 1.00), stretchability (R2 = 1.00), hardness (R2 = 0.99), and moldability (R2 = 0.53) of pounded yam samples can be predicted by the starch, amylose, and protein contents of yam tubers estimated by near-infrared spectroscopy. CONCLUSION TPA and Hunter colorimeter can be used as medium-high throughput methods to evaluate the textural quality and color of pounded yam in place of the sensory panelists

Windborne long-distance migration of malaria mosquitoes in the Sahel

Over the past two decades efforts to control malaria have halved the number of cases globally, yet burdens remain high in much of Africa and the elimination of malaria has not been achieved even in areas where extreme reductions have been sustained, such as South Africa1,2. Studies seeking to understand the paradoxical persistence of malaria in areas in which surface water is absent for 3–8 months of the year have suggested that some species of Anopheles mosquito use long-distance migration3. Here we confirm this hypothesis through aerial sampling of mosquitoes at 40–290 m above ground level and provide—to our knowledge—the first evidence of windborne migration of African malaria vectors, and consequently of the pathogens that they transmit. Ten species, including the primary malaria vector Anopheles coluzzii, were identified among 235 anopheline mosquitoes that were captured during 617 nocturnal aerial collections in the Sahel of Mali. Notably, females accounted for more than 80% of all of the mosquitoes that we collected. Of these, 90% had taken a blood meal before their migration, which implies that pathogens are probably transported over long distances by migrating females. The likelihood of capturing Anopheles species increased with altitude (the height of the sampling panel above ground level) and during the wet seasons, but variation between years and localities was minimal. Simulated trajectories of mosquito flights indicated that there would be mean nightly displacements of up to 300 km for 9-h flight durations. Annually, the estimated numbers of mosquitoes at altitude that cross a 100-km line perpendicular to the prevailing wind direction included 81,000 Anopheles gambiae sensu stricto, 6 million A. coluzzii and 44 million Anopheles squamosus. These results provide compelling evidence that millions of malaria vectors that have previously fed on blood frequently migrate over hundreds of kilometres, and thus almost certainly spread malaria over these distances. The successful elimination of malaria may therefore depend on whether the sources of migrant vectors can be identified and controlled

El sorgo regado: una alternativa para la sostenilidad del regadío en el valle del río Senegal

Póster presentado en el I Congreso en Investigación en Agricultura para el desarrollo, celebrado en Madrid el 17 y 18 de octubre de 2011.Después de las hambrunas de los años 70 y 80 en Mauritania y países vecinos, el Banco Mundial auspició el desarrolló del regadío en la región con el fin de mejorar la seguridad alimentaria. En Mauritania, la mayoría de los perímetros se diseñaron para el monocultivo de arroz y se siguió una política de apoyo único a dicho cultivo. Sin embargo, en muchos casos el sistema no conseguía proporcionar el agua necesaria para alcanzar el rendimiento esperado y parte de los perímetros se abandonaron. La mayoría de los que continúan siguen con el cultivo del arroz de manera precaria. Recientemente el gobierno mauritano ha reconocido la necesidad de diversificar los cultivos regados como una de las vías para mejorar la sostenibilidad de los regadíos. El primer cultivo introducido ha sido el sorgo para alimento humano ya que existen variedades mejoradas desarrolladas en la región además de una demanda local. En este contexto, el objetivo de este trabajo es la comparación de los cultivos de sorgo y arroz en términos de rendimiento y productividad del agua a escala de parcela de pequeño agricultor.El presente estudio ha sido financiado por la Agencia Española de Cooperación Internacional para el Desarrollo (AECID) junto con el Ministerio de Desarrollo Rural de Mauritania.Peer Reviewe

Contribution of sorghum to productivity of small-holder irrigation schemes: On-farm research in the Senegal River Valley, Mauritania

In Mauritania, most irrigated land was designed for, and remains devoted to, rice (Oryza sativa L.) cultivation. Decades after introduction, however, yield remains below expectations, irrigated land is gradually being abandoned, and now crop diversification is promoted to improve sustainability of irrigated agriculture. This paper presents evidence of the potential, and limitations, of sorghum (Sorghum bicolor L. Moench) cropping in small-holder irrigation schemes along the Mauritanian side of the Senegal River Valley. Results are based on 3-years of on-farm participatory research (2007-2009) carried out at five irrigation schemes in collaboration with farmers and national research and extension services. Grain yield, water productivity and gross margin of sorghum and rice were compared at plot level. Global average grain yield over years and schemes was 2.5tha-1 for sorghum, ranging from 1.7tha-1 to 3.2tha-1, compared to 5.6tha-1 for rice, ranging from 4.0tha-1 to 7.3tha-1, even though both crops had similar total above-ground biomass at maturity. Sorghum required less irrigation water than rice (435 vs. 601mm) but the smaller yield resulted in similar irrigation water productivity (0.87 vs. 0.96kgm-3) and fuel (pumping) productivity (1.71 vs. 1.93kgMJ-1). Despite smaller yields, however, sorghum profitability was significantly greater than rice (1172 vs. 788 € ha-1), due to higher market price and, in the case of one scheme, lower irrigation costs. Main constraints identified in sorghum cropping were (i) poor crop establishment because of late sowing and water logging; (ii) neglected weed management; and (iii) mismatch between irrigation delivery schedules and water requirements. The causes of these constraints are particularities of rice production systems (design and heavy soil) and farmers' habits acquired with traditional rainfed sorghum cropping during the wet season.The analyses presented here reveal that sorghum cropping is a profitable option to rice for small-holder farmers, particularly on light-textured soils within the irrigation schemes. Furthermore, large variability of results among sorghum farmers and the high above-ground biomass at maturity suggests scope for improving grain yield and water productivity. Challenges remain, however, for adoption of sorghum in irrigated agriculture in Mauritania. National agricultural policies must ensure access to credit and agricultural inputs (seeds and fertilizers) and consider specific requirements for crop diversification (type of soil, irrigation distribution) in both rehabilitation of existing schemes and in design and construction of new ones. © 2012 Elsevier Ltd.This study was supported by a project funded by the Spanish Agency for International Cooperation for Development and the Ministry of Rural Development in Mauritania.Peer Reviewe