Phylogenetic diversity and relationships among 40 rice accessions using morphological and RAPDs techniques

Morphological characterization of 40 rice accessions using 14 agro-botanical traits was done in a field experiment in an augmented randomized complete block design. The aim of the work was to study variations and to select lines that can be used as potential parents in a future breeding program. The single linkage clustering, the Principal Components Axes and a morphological dendrogram were used to group the accessions. Genetic relatedness among accessions based on random amplified polymorphic DNA (RAPD) molecular marker data was also presented in form of a dendrogram using the Unweighted Pair Group Method with Arithmetic mean (UPGMA). Relative effectiveness of the RAPD markers and genetic diversity among accessions as revealed by botanical descriptors were compared.The single linkage cluster technique classified the 40 accessions into six morphological groups whereas the PCA re-ordered the accessions into four broad groups that had within cluster similarities and inter-cluster morphological variations. RAPDs were highly polymorphic, more discriminatory and informative as they were able to differentiate more pairs of accessions than the botanical descriptors. IITA rice accessions TOX 3052-46-3-3-2-1 and TOX 3027-44-1-E4-2-2 and Brazilian accessions (CLSELECCION 3B and 450) that performed better than checks could be selected for a future breeding program

Seed systems smallholder farmers use

Seed can be an important entry point for promoting productivity, nutrition and resilience among smallholder farmers. While investments have primarily focused on strengthening the formal sector, this article documents the degree to which the informal sector remains the core for seed acquisition, especially in Africa. Conclusions drawn from a uniquely comprehensive data set, 9660 observations across six countries and covering 40 crops, show that farmers access 90.2 % of their seed from informal systems with 50.9 % of that deriving from local markets. Further, 55 % of seed is paid for by cash, indicating that smallholders are already making important investments in this arena. Targeted interventions are proposed for rendering formal and informal seed sector more smallholder-responsive and for scaling up positive impacts

Genetic Variability In Morphological And Physiological Traits Within And Among Rice Species And Their Interspecific Progenies

This study compares genetic variation in morpho-physiological traits within and among five groups of Oryza species. Several morphological and phenological characters were measured in field trials. Results showed that genetic variation exits among and within these groups for the characters measured. More O. glaberrima and traditional O. sativa possess attributes which indicate they are better adapted to suboptimal growing conditions that characterize rice cultivation in West Africa, but are poor yielding. The interspecific progenies possess characters that cover the range of both their parents. Cluster analysis amalgamated some as possessing the adaptive morphological traits of their O.glaberrima parents, and the panicle and yield attributes of improved O. sativa parents. O. sativa of temperate origin, but of tropical japonica genetic background did not show characters for adaptability to the West African upland conditions, but was similar to interspecifics and other adapted genotypes groups that possess panicle and spikelet characteristics. Those ones could be exploited for extending present yield levels.Cette étude compare la variation génétique de paramètres morpho-physiologiques au sein et entre cinq groupes d\'espèces Oryza. Plusieurs caractères morphologiques et phénologiques ont été mesurés dans des essais conduits au champ. Les résultats ont montré qu\'il existe, pour les caractères mesurés, une variation génétique au sein et entre les groupes étudiés. Un nombre important d\'espèces O. glaberrima et O. sativa traditionnelles ont des attributs qui indiquent qu\'elles sont mieux adaptées aux conditions suboptimales de la culture de riz en Afrique occidentale. Elles ont, cependant, un rendement faible. Les descendants interspécifiques possèdent des attributs qui couvrent la gamme des caractères de leurs parents. L\'analyse de groupement a identifié certains comme présentant les caractères morphologiques d\'adaptation de leurs parents O. glaberrima, et des caractères de panicule et de rendement des parents améliorés O. sativa. Les espèces O. sativa d\'origine tempérée, mais de fond génétique japonica tropical n\'ont pas démontré une capacité d\'adaptation aux conditions de culture de riz pluvial en Afrique de l\'Ouest. Par contre, elles étaient semblables aux descendants interspécifiques et autres groupes de génotypes adaptés quant aux caractéristiques des panicules et des grains. Celles-ci pourraient être exploitées pour l\'amélioration des niveaux de rendement actuels. Keywords: Germplasm characterization, Oryza glaberrima, Oryza sativa, genetic variation, West Africa; Caractérisation de germplasm, Oryza glaberrima, Oryza sativa, variation génétique, Afrique de l'Ouest..Agronomie Africaine Vol. 16 (1) 2004: pp. 15-3

Seed exchange networks for agrobiodiversity conservation. A review

The circulation of seed among farmers is central to agrobiodiversity conservation and dynamics. Agrobiodiversity, the diversity of agricultural systems from genes to varieties and crop species, from farming methods to landscape composition, is part of humanity's cultural heritage. Whereas agrobiodiversity conservation has received much attention from researchers and policy makers over the last decades, the methods available to study the role of seed exchange networks in preserving crop biodiversity have only recently begun to be considered. In this overview, we present key concepts, methods, and challenges to better understand seed exchange networks so as to improve the chances that traditional crop varieties (landraces) will be preserved and used sustainably around the world. The available literature suggests that there is insufficient knowledge about the social, cultural, and methodological dimensions of environmental change, including how seed exchange networks will cope with changes in climates, socio-economic factors, and family structures that have supported seed exchange systems to date. Methods available to study the role of seed exchange networks in the preservation and adaptation of crop specific and genetic diversity range from meta-analysis to modelling, from participatory approaches to the development of bio-indicators, from genetic to biogeographical studies, from anthropological and ethnographic research to the use of network theory. We advocate a diversity of approaches, so as to foster the creation of robust and policy-relevant knowledge. Open challenges in the study of the role of seed exchange networks in biodiversity conservation include the development of methods to (i) enhance farmers' participation to decision-making in agro-ecosystems, (ii) integrate ex situ and in situ approaches, (iii) achieve interdisciplinary research collaboration between social and natural scientists, and (iv) use network analysis as a conceptual framework to bridge boundaries among researchers, farmers and policy makers, as well as other stakeholders

Seed exchange networks for agrobiodiversity conservation. A review

The circulation of seed among farmers is central to agrobiodiversity conservation and dynamics. Agrobiodiversity, the diversity of agricultural systems from genes to varieties and crop species, from farming methods to landscape composition, is part of humanity's cultural heritage. Whereas agrobiodiversity conservation has received much attention from researchers and policy makers over the last decades, the methods available to study the role of seed exchange networks in preserving crop biodiversity have only recently begun to be considered. In this overview, we present key concepts, methods, and challenges to better understand seed exchange networks so as to improve the chances that traditional crop varieties (landraces) will be preserved and used sustainably around the world. The available literature suggests that there is insufficient knowledge about the social, cultural, and methodological dimensions of environmental change, including how seed exchange networks will cope with changes in climates, socio-economic factors, and family structures that have supported seed exchange systems to date. Methods available to study the role of seed exchange networks in the preservation and adaptation of crop specific and genetic diversity range from meta-analysis to modelling, from participatory approaches to the development of bio-indicators, from genetic to biogeographical studies, from anthropological and ethnographic research to the use of network theory. We advocate a diversity of approaches, so as to foster the creation of robust and policy-relevant knowledge. Open challenges in the study of the role of seed exchange networks in biodiversity conservation include the development of methods to (i) enhance farmers' participation to decision-making in agro-ecosystems, (ii) integrate ex situ and in situ approaches, (iii) achieve interdisciplinary research collaboration between social and natural scientists, and (iv) use network analysis as a conceptual framework to bridge boundaries among researchers, farmers and policy makers, as well as other stakeholders