oalib
Search Results: 1 - 10 of 100 matches for " "
All listed articles are free for downloading (OA Articles)
Page 1 /100
Display every page Item
The African Rice Oryza glaberrima Steud: Knowledge Distribution and Prospects  [cached]
Yves Agnoun,Samadori S. H. Biaou,M. Sié,R. S. Vodouhè
International Journal of Biology , 2012, DOI: 10.5539/ijb.v4n3p158
Abstract: This paper presents a consolidated balance-sheet on the botanical and historical evidence for the role of the cultivated African rice species (Oryza glaberrima Steud) in West and Central Africa as well as its geographical distribution. Because Oryza glaberrima has survived without the help and interference from human, it has developed adaptive and protective mechanisms for resisting major biotic and abiotic stresses. Oryza glaberrima is also very plastic with two major ecotypes: the floating and the non floating, and presents natural hybridization and admixture with its wild parents and the Asian cultivated rice Oryza sativa. Several ecotypes showed good aptitude in response to climatic change effects such as drought, flood, pests and diseases. This review presents several phenotypic diversity aspects on O. glaberrima and highlights its ecological and genetic structuring as well as the management of its diversity. Even if the African rice has undergone less diversification than the Asian rice in their evolutionary process, it presents some interesting assets which are being suggested to exploit through varietal improvement programs.
Varietal Differences in Lodging Resistance of African Rice (Oryza glaberrima Steud.)  [PDF]
K. Futakuchi,M. Fofana,M. Sie
Asian Journal of Plant Sciences , 2008,
Abstract: To identify resistant genotypes to lodging in African rice (Oryza glaberrima), 6 genotypes, three of which were selected by prescreening for the resistance and the remaining three were used in an interspecific breeding program at WARDA, were tested in terms of resistance to lodging. The trial was conducted in rainfed upland in 2005 and in irrigated lowland in 2006 and all genotypes showed higher yield and larger plant length in 2006 than in 2005. There was a clear varietal difference in lodging incidence of the O. glaberrima genotypes at maturity, which was ranged from 0.0 to 91.0% and from 68.6 to 99.7% in 2005 and 2006, respectively. In 2005, four O. glaberrima genotypes, TOG 7235, IRGC Accession Code 104038, CG 14 and CG 20, depicted the resistance at maturity since their lodging incidences were from 0.0 to 6.7%. With heavier panicles by higher yield and larger plant length in 2006, however, two of those four genotypes almost completely lodged at maturity. The remaining two genotypes, TOG 7235 and CG 14, showed moderately low lodging incidences of 74.1 and 68.6%, respectively. However, those rates are still very high as a commercial variety and further screening for lodging resistance is necessary.
Evaluation of Oryza sativa x O. glaberrima derived progenies for resistance to rootknot nematode and identification of introgressed alien chromosome segments using SSR markers
IK Bimpong, AL Carpena, MS Mendioro, L Fernandez, J Ramos, G Reversat, DS Brar
African Journal of Biotechnology , 2010,
Abstract: The genus Oryza has two cultivated species, Asian rice (Oryza sativa L.) and African rice (Oryza glaberrima Steud.) and 22 wild species. O. glaberrima is low yielding but has useful genes for resistance to biotic and abiotic stresses. Introgression lines derived from backcrossing of O. sativa x O. glaberrima, using O. sativa as recurrent parent, were evaluated for tolerance to root-knot nematode (Meloidogyne graminicola). Testing in sick plots infested with nematodes showed reduction in plant height, shoot and root biomass and leaf area index compared to the control. Based on gall rating and the ratio of the final population to the initial population of nematodes (Pf/Pi ratio), three introgression lines were found to be resistant to nematodes (IR80311-9-B-B-1-2 and IR80311-2-B-B-1-2 under screenhouse and IR80311-48-BB- 1 under phytotron conditions). Gall rating and the Pf/Pi ratio showed positive correlation (r = 0.61). Analysis of 122 introgression lines using simple sequence repeat (SSR) markers detected introgression of O. glaberrima segments into O. sativa.
Better Exploitation of African Rice (Oryza glaberrima Steud.) in Varietal Development for Resource-Poor Farmers in West and Central Africa
Koichi Futakuchi,Moussa Sie
Agricultural Journal , 2013,
Abstract: Inter specific breeding between Oryza sativa and Oryza glaberrima was started at WARDA with the basic concept of combining the resistance of O. glaberrima to local constraints in West and Central Africa (WCA) with the high yielding ability of O. sativa. Developed interspecific progeny is now called as NERICA, which was named after New Rice for Africa and 18 upland NERICA varieties and eleven lowland NERICA varieties have been released or widely disseminated in several WCA countries. Some of them were beyond WCA and released in other sub-Saharan Africa countries such as Uganda. However, a gap is still existing between current NERICA varieties and O. glaberrima lines with special reference to resistance to local constraints in WCA. In this study, published data and also some additional unpublished data on the performance of NERICA and O. glaberrima were critically reviewed and possible improvements and further directions in rice breeding with better exploitation of O. glaberrima were proposed.
Agrobotanical Characteristics of Some West African Indigenous Species of the a Genome Complex of the Genus Oryza Linn  [PDF]
Francisca Aladejana,Julius Olaoye Faluyi
International Journal of Botany , 2007,
Abstract: This study collected and characterized accessions of three indigenous and one cultivated species of the A genome complex of the genus Oryza Linn. with the objective of identifying the valuable botanical and agro-botanical characters in them. The germplasm collection confirmed that the four species of the A-genome complex: Oryza barthii A. Chev., Oryza glaberrima Steud, O. longistaminata A. Chev. and Roehr and O. sativa Linn. are abundant in the savanna agroecology of Nigeria. The restricted occurrence of O. glaberrima suggests that it has attained the status of a lost crop. The species studied have been delineated on the basis of morphometric parameters involving awns, grain length and shape, panicle branching, rhizomatous habit, ligule shape and form, presence or absence of secondary branches and perennial or annual habit. The results have been able to identify botanical attributes for species differentiation and useful agronomic attributes in the wild rice species as genetic resources both for the improvement of O. sativa and possibly some of the wild species per se. These attributes include: insensitivity to photoperiod, long grains, awnlessness, dense panicle, high yield parameters, high food value and tillering habit. Findings also revealed considerable variability in the gene pool of the species studied for the improvement of the rice crop.
Molecular profiling of interspecific lowland rice populations derived from IR64 (Oryza sativa) and Tog5681 (Oryza glaberrima)
MN Ndjiondjop, K Semagn, M Sie, M Cissoko, B Fatondji, M Jones
African Journal of Biotechnology , 2008,
Abstract: Several lowland NERICAs (New Rice for Africa) were derived from crosses between IR64 (an Oryza sativa subsp. indica variety) and Tog5681 (an Oryza glaberrima variety) that possess useful traits adapted to lowland conditions in West Africa. The proportion of parental genomic contribution and extent of genetic differences among these sister lines is unknown at the molecular level. The objectives in this study were therefore to determine, with 60 SSR markers that cover 1162 cM of the rice genome, the frequency and magnitude of deviations from the expected parental contributions among 21 BC2F10, 17 BC3 F8 and 10 BC4F8 lines and determine patterns of their genetic relationships. The estimated average O. glaberrima genome coverage was 7.2% (83.5 cM) at BC2F10, 8.5% (99.3 cM) at BC3F8 and 8.1% (93.8 cM) at BC4F8 lines. The O. sativa parent accounted for 73.2% (851.3 cM) at BC2F10, 82.6% (959.5 cM) at BC3F8 and 78.2% (908.6 cM) at BC3F8. Non-parental alleles were detected at all 3 backcross generations but the frequency of such alleles at BC2 (8.8%) was twice that of BC3F8 (3.4%) and nine times that of BC4F8 (0.9%). Both cluster and principal component analyses revealed two major groups irrespective of the level of backcross generations and the proportion of parental genome contribution.
Screening of African rice, oryza glaberrima steud, for resistance to the African rice gall midge orseolia oryzivora Harris and Gagne
MN Ukwungwe, CT Williams, O Okhidlevble
Journal of Food Technology in Africa , 1999,
Abstract:
Molecular Profiling of Interspecific Lowland Rice Progenies Resulting from Crosses between TOG5681 and TOG5674 (Oryza glaberrima) and IR64 (Oryza sativa)  [cached]
Yves Agnoun,M. Sié,G. Djedatin,K. N. Dramé
International Journal of Biology , 2012, DOI: 10.5539/ijb.v4n3p19
Abstract: Two Outstanding Oryza glaberrima (2n = 24, AA) varieties TOG5681 and TOG5674 were used as male donor parents with IR64, the high-yielding improved Asian rice variety used as recurrent female parent by the International Rice Research Institute (IRRI) to develop 18 BC3F1 interspecific lowland rice progenies. The proportion of parental genomic contribution and the extent of genetic differences among these lines were assessing using 36 microsatellites markers. The average genomic contribution of the donor TOG5681 and that of the recurrent IR64 within their 12 interspecific lines derived from IR64xTOG5681 cross were estimated to 13.2% and 79.8% respectively. Using 33 out of the 36 SSR markers, the average genome introgression rate of TOG5674 and that of IR64 within their 6 progenies were estimated to 8.7% and 85.5% respectively. In addition, heterozygosity and non-parental alleles were also identified. Clustering analysis technique using NTSYS classified the progenies into six groups and group five is closely related to IR 64.
Identification of a Rice stripe necrosis virus resistance locus and yield component QTLs using Oryza sativa × O. glaberrima introgression lines
Andrés Gutiérrez, Silvio Carabalí, Olga Giraldo, César Martínez, Fernando Correa, Gustavo Prado, Joe Tohme, Mathias Lorieux
BMC Plant Biology , 2010, DOI: 10.1186/1471-2229-10-6
Abstract: We built a set of 64 chromosome segment substitution lines carrying contiguous chromosomal segments of African rice Oryza glaberrima MG12 (acc. IRGC103544) in the genetic background of Oryza sativa ssp. tropical japonica (cv. Caiapó). Well-distributed simple-sequence repeats markers were used to characterize the introgression events. Average size of the substituted chromosomal segments in the substitution lines was about 10 cM and covered the whole donor genome, except for small regions on chromosome 2 and 4. Proportions of recurrent and donor genome in the substitution lines were 87.59% and 7.64%, respectively. The remaining 4.78% corresponded to heterozygotes and missing data. Strong segregation distortion was found on chromosomes 3 and 6, indicating the presence of interspecific sterility genes. To illustrate the advantages and the power of quantitative trait loci (QTL) detection using substitution lines, a QTL detection was performed for scored traits. Transgressive segregation was observed for several traits measured in the population. Fourteen QTLs for plant height, tiller number per plant, panicle length, sterility percentage, 1000-grain weight and grain yield were located on chromosomes 1, 3, 4, 6 and 9. Furthermore, a highly significant QTL controlling resistance to the Rice stripe necrosis virus was located between SSR markers RM202-RM26406 (44.5-44.8 cM) on chromosome 11.Development and phenotyping of CSSL libraries with entire genome coverage represents a useful strategy for QTL discovery. Mapping of the RSNV locus represents the first identification of a genetic factor underlying resistance to this virus. This population is a powerful breeding tool. It also helps in overcoming hybrid sterility barriers between species of rice.Asian rice (Oryza sativa L.) is one of the most important food crops for mankind and is considered to be a model system for molecular genetic research in monocots, due to its small genome size and its synteny with other cereal crop
Robustness and Strategies of Adaptation among Farmer Varieties of African Rice (Oryza glaberrima) and Asian Rice (Oryza sativa) across West Africa  [PDF]
Alfred Mokuwa, Edwin Nuijten, Florent Okry, Béla Teeken, Harro Maat, Paul Richards, Paul C. Struik
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0034801
Abstract: This study offers evidence of the robustness of farmer rice varieties (Oryza glaberrima and O. sativa) in West Africa. Our experiments in five West African countries showed that farmer varieties were tolerant of sub-optimal conditions, but employed a range of strategies to cope with stress. Varieties belonging to the species Oryza glaberrima – solely the product of farmer agency – were the most successful in adapting to a range of adverse conditions. Some of the farmer selections from within the indica and japonica subspecies of O. sativa also performed well in a range of conditions, but other farmer selections from within these two subspecies were mainly limited to more specific niches. The results contradict the rather common belief that farmer varieties are only of local value. Farmer varieties should be considered by breeding programmes and used (alongside improved varieties) in dissemination projects for rural food security.
Page 1 /100
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.