Time filter

Source Type

Port-Vila, Vanuatu

Lebot V.,CIRAD BIOS | Michalet S.,CNRS Microbial Ecology | Legendre L.,CNRS Microbial Ecology
Journal of Food Composition and Analysis | Year: 2016

The objectives of the present study were to develop a simple high performance thin layer chromatography (HPTLC)-based protocol: (i) to allow high-throughput profiling of phenolic compounds of microwaved roots from 295 sweet potato varieties and breeding lines, (ii) to quantify the content of anthocyanins and caffeoylquinic acid (CQA) derivatives, and (iii) to determine their respective contributions to the antioxidant activity of sweet potato methanolic extracts using the DPPH test. Analysed accessions were separated into three groups: white-fleshed (n = 100), orange-fleshed (n = 64) and purple-fleshed (n = 131). Purple-fleshed accessions presented the highest mean CQA content. After DPPH treatment and transmittance scanning of the plate at 517 nm, the most active free radical scavengers were found to be the four CQAs (CGA, 3,4-, 4,5- and 3,5-diCQA) while the anthocyanins were found to be less active. The total antioxidant capacity of the sweet potato methanolic extracts was mostly linked to total CQAs content. This method can now be used for fast routine analysis and selection of sweet potato breeding clones. © 2016 .

The capability of Pacific Island countries' agriculture to adapt to climatic and environmental changes is analysed. After presenting key features of the region's food cropping systems, findings of genetic diversity studies for the most important food crops are reviewed and their implications for adaptation are discussed. Biophysical and economic vulnerabilities of the food system are identified. For the major food crops, the needs for genetic improvement are detailed, and practical solutions for broadening genetic bases are suggested. The paper concludes by identifying areas for additional research on crops and agro-ecosystems adaptation aiming at increasing the flexibility of agriculture in the Pacific. In this region, plant breeding has to cope with the insularity constraints of the small island states. The new varieties need to satisfy farmers' agronomic requirements in very diverse environments. However, because of genotype-by-environment interactions (G × E), it is difficult to identify a variety that would be accepted by most farmers on different islands. A new type of breeding programme with a pragmatic approach is therefore necessary. The geographical distribution of allelic diversity appears as a practical and cost-efficient solution. © 2013 Springer Science+Business Media Dordrecht.

Lebot V.,CIRAD BIOS | Simeoni P.,Geoconsulte Ltd.
Human Ecology | Year: 2015

To study food production systems of six communities located on six different islands of Vanuatu we selected villages in zones of low and high population pressures. We measured land availability, soil fertility, genetic resources, average yields of food gardens, their plant densities, traditional knowledge richness (TKR), and household incomes and expenses. We analyzed a total of 224 plots belonging to 30 farmers and identified 13 root crop species with the total number of cultivars in communities ranging from 74 to 261. Surprisingly, villages under high population pressure have shorter fallow periods but higher yields. In both zones, women have higher TKR. In high population pressure villages there are signs of soil fertility reduction and mineral depletion but no signs of significant decrease in soil fertility after the first year of cultivation, indicating that root crop species remove limited amounts of total N and minerals per year. The purchase of imported foods is associated with a sociocultural change in diets rather than pressures on land or soils. Our quantitative and integrative methodology allows clear differentiation between villages under different pressures and can be used to assess levels of resilience and vulnerability. © 2015 Springer Science+Business Media New York.

Somarriba E.,Tropical Agriculture Research and Higher Education Center | Lachenaud P.,CIRAD BIOS
Forests Trees and Livelihoods | Year: 2013

Cocoa was used as a fruit in its native range. Cocoa fruits were harvested from "wild" cocoa stands embedded into the forests growing on the high terraces of the Amazon and Orinoco river systems and in the Guiana shield. "Wild" cocoa stands resulting from human intervention and disturbance of the local forest ecosystem are called subspontaneous cocoa stands. We propose that these sub-spontaneous cocoa forests are a new type of cocoa production system that we propose to call "successional cocoa agroforest." This article (1) describes the history of extractive cocoa in the Amazon basin, (2) outlines the possible historic path of domestication and use of cocoa subspontaneous stands, (3) specifies the biophysical and cultural processes that determine the creation-destruction-regeneration of the successional cocoa agroforest, (4) proposes a model for the functioning of this cocoa production system, and (5) documents the scarce information available on the changes in both the forest vegetation and biomass, and cocoa population numbers along the course of forest succession. This study shows the need to broaden the popular five classes classification of coffee and cocoa production systems (open sun cultivation, specialized shade, commercial shade, mixed shade, and rustic systems) to include a sixth type, the "successional cocoa agroforest." © 2013 Taylor &Francis.

Lebot V.,CIRAD BIOS | Lawac F.,VARTC | Michalet S.,University Claude Bernard Lyon 1 | Legendre L.,University Claude Bernard Lyon 1
Plant Genetic Resources: Characterisation and Utilisation | Year: 2015

The starchy corms of taro (Colocasia esculenta) are consumed throughout the tropics and are essential for food security in many developing countries. Taro corms are increasingly processed into fries, chips, flours or flakes in urban areas, and varieties with attractive corm flesh colours are now needed. The identification of flavonoids in taro corms would add value to this crop. The present study developed a high-performance thin layer chromatography (HPTLC) protocol for the high-throughput screening of flavonoids in taro germplasm. Overall, 350 different accessions were analysed including 259 varieties from Vanuatu, one from Vietnam, eight from Thailand, eight from the Philippines, six from Malaysia, two from Japan and 18 from Indonesia. Forty-eight breeding lines (hybrids) including 21 from Vanuatu, 21 from Samoa, four from Hawaii and two from Papua New Guinea were also analysed. Ten flavones, namely luteolin-6-C-hexoside-8-C-pentoside, schaftoside, luteolin-3′,7-di-O-glucoside, homoorientin, isovitexin, orientin, luteolin-4′-O-glucoside, luteolin-7-O-glucoside, vitexin and apigenin-7-O-glucoside, were successfully detected in the corm and are responsible for the attractive yellow colour of the flesh and fibres. Quantitatively, luteolin-6-C-hexoside-8-C-pentoside and schaftoside were the most important of all the detected flavonoids. However, only 18% of the varieties analysed presented these two compounds and 80% presented poor flavonoid composition. No geographical structure of the variation was detected and the most flavone-rich varieties originated from Vanuatu, Thailand, the Philippines, Malaysia and Indonesia. The compounds detected in the present study were significantly and positively correlated, suggesting that there is potential for fast improvement through controlled crosses, subsequent evaluation of full-sib progenies and cloning of elite individuals. Copyright © NIAB 2015

Discover hidden collaborations