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Search Results: 1 - 10 of 94330 matches for " Matthew W. Blair "
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Quantification of drought tolerance in Ethiopian common bean varieties  [PDF]
Asrat Asfaw, Matthew W. Blair
Agricultural Sciences (AS) , 2014, DOI: 10.4236/as.2014.52016
Abstract:

Understanding the level of drought tolerance of the varieties available in each country is of paramount importance for breeding common bean for drought adaptation. The goal of this study was to evaluate 25 common bean genotypes of which 24 were released/recommended varieties for production by farmers and one was a drought tolerant check. The genotypes were planted at two sites in Ethiopia, Hawasssa and Amaro, using variable sowing dates, one that was early to avoid drought and one that was late to expose the crop to drought. The experiments were repeated over two years in Hawassa and one year in Amaro. This resulted in treatments with high and low total seasonal rainfall and six environments for analysis. The impact of drought stress on the trait expression of the varieties was not uniform across traits assessed and varieties tested. The effect of drought on photosynthate translocation and partitioning traits was much greater than on yield component traits in the varieties studied. This indicating less breeding efforts has been made in improving the varieties ability to mobilize photosynthate to the developing grain as compared to the yield component traits. Drought tolerant varieties like Hawassa Dume maintained better photosynthate translocation and partitioning than the drought sensitive varieties like Brown Speckled bean. Hawassa Dume also showed better yield stability and performed well under both drought stress and nonstress conditions. Our results indicate the relevance of high levels of photosynthate translocation and partitioning as an effective selection objective for improving drought tolerance in common bean. The information generated on the drought tolerance of the available varieties should help in the design of a breeding strategy that incorporates adaptation traits with commercial characteristics preferred by common bean farmers for varieties to be grown in diverse environments.

Effects of Moisture Deficit on the Yield of Cowpea Genotypes in the Guinea Savannah of Northern Ghana  [PDF]
Damba Yahaya, Nicholas Denwar, Matthew W. Blair
Agricultural Sciences (AS) , 2019, DOI: 10.4236/as.2019.104046
Abstract: Cowpea is multipurpose, leguminous, high protein crop in the tropics that provides food for humans and fodder for animals. The crop adds nitrogen and other nutrients to the soil through symbiotic relationship with rhizobia and direct decomposition of cowpea by-products. Despite its multiple benefits for humankind, the yield of cowpea is far below its potential and its production in the crop’s birthplace of Africa is especially affected by abiotic factors. Soil moisture deficit is one of the main abiotic factors that affect the yield of cowpea in the semi-arid tropics, including the Sahelian and Guinea Savannah regions in West Africa. Even though cowpea is a drought tolerant legume, different genotypes respond differently to drought, resulting in up to 100% or more yield increases in the case of resistant genotypes or 50% or more yield loss in case of susceptible types. Mitigating the effect of soil moisture deficit on cowpea production requires selection of genotypes that can withstand drought. With this in mind, the goal of this study was to identify drought tolerant cowpea germplasm for the Savannah region of Northern Ghana using cultivated genotypes from the United States Department of Agriculture (USDA) tested with and without irrigation at the Bontanga irrigation facility during the dry season in 2018. Fifty genotypes were used, which included 45 imported from USDA and five (5) local genotypes from the Savannah Agriculture Research Institute (SARI). The experiment had 2 × 50 factorial treatments (irrigation × genotypes) and consisted of randomized complete block design with three (3) replications per treatment. Two (2) watering regimes were introduced namely, drought stressed (no irrigation) and non-stressed/control (irrigated). Morpho-physiological, phenological and yield data were taken on the cowpeas evaluated with drought tolerance assessed based on grain yield data and derived indices. All parameters measured showed significant differences (p ≤ 0.05) except for the number of branches per plant. Genotypes PI339600, PI527263, PI527302, PI582793, PI582867 and SARI-6-2-6 produced high grain yields under both drought stress and non-stress conditions. These genotypes could be exploited for future breeding programs for developing drought tolerant cowpea varieties for the savannah ecology and other areas with similar environmental conditions.
Screening Cowpea (Vigna unguiculata (L.) Walp.) Genotypes for Enhanced N2 Fixation and Water Use Efficiency under Field Conditions in Ghana  [PDF]
Damba Yahaya, Nicholas Denwar, Mustapha Mohammed, Matthew W. Blair
American Journal of Plant Sciences (AJPS) , 2019, DOI: 10.4236/ajps.2019.104047
Abstract: To explore the variations in symbiotic N2 fixation and water use efficiency in cowpea, this study evaluated 25 USDA cowpea genotypes subjected to drought under field conditions at two locations (Kpachi and Woribogu) in the Northern region of Ghana. The 15N and 13C natural abundance techniques were respectively used to assess N2 fixation and water use efficiency. The test genotypes elicited high symbiotic dependence in association with indigenous rhizobia, deriving between 55% and 98% of their N requirements from symbiosis. Consequently, the amounts of N-fixed by the genotypes showed remarkable variations, with values ranging from 37 kg·N-fixed·ha-1 to 337 kg·N-fixed·ha-1. Most genotypes elicited contrasting symbiotic performance between locations, a finding that highlights the effect of complex host/soil microbiome compatibility on the efficiency of the cowpea-rhizobia symbiosis. The test genotypes showed marked variations in water use efficiency, with most of the genotypes recording higher δ13C values when planted at Kpachi. Despite the high symbiotic dependence, the grain yield of the test cowpeas was low due to the imposed drought, and ranged from 56 kg/ha to 556 kg/ha at Kpachi, and 143 kg/ha to 748 kg/ha at Woribogu. The fact that some genotypes could grow and produce grain yields of 627
Contenido de hierro y cinc en la semilla y su respuesta al nivel de fertilización con fósforo en 40 variedades de fríjol colombianas
Astudillo,Carolina; Blair,Matthew W.;
Agronomía Colombiana , 2008,
Abstract: the improvement of beans in colombia has produced a large number of varieties for different agro-ecological zones and with different adaptation ranges. the objective of this research was to determine the nutritional quality of common bean genotypes from colombia in terms of iron and zinc content of the seed and to determine how soil fertilization with high or low levels of phosphorus impact yield with these minerals . a total of 40 genotypes were evaluated including released varieties from ica or corpoica (of the diacol or ica series), traditional landrace varieties from valle, nari?o and norte de santander, and ciat breeding lines as control. these were planted in darién in the first semester of 2004 under two-fertilization treatments in complete randomized block experiments with three repetitions. iron and zinc content was measured in harvested seed using the spectrophotometric method of atomic absorption. variance analysis showed significant differences for mineral content among genotypes, and between high and low phosphorus fertilization levels with averages of 61.5 and 53.2 ppm for iron and 26.3 and 23.1 for zinc, respectively. given these results, phosphorus fertilization can increase iron content in bean seeds, but can reduce zinc content in seeds.
Contenido de hierro y cinc en la semilla y su respuesta al nivel de fertilización con fósforo en 40 variedades de fríjol colombianas
Astudillo Carolina,Blair Matthew W.
Agronomía Colombiana , 2008,
Abstract: El mejoramiento del fríjol en Colombia ha producido un amplio número de variedades para diferentes zonas agroecológicas y con diferentes rangos de adaptación. Los objetivos de esta investigación fueron determinar la calidad nutricional del fríjol en Colombia en cuanto al contenido de hierro y cinc en el grano y entender cómo los niveles de fertilización del suelo alta y baja en fósforo afectan tanto el rendimiento como el nivel de estos minerales. Se evaluaron 40 genotipos arbustivos dentro de los que se encuentran variedades liberadas por el ICA o Corpoica (series Diacol e ICA), cultivares tradicionales de los departamentos de Valle, Nari o, Norte de Santander, y líneas CIAT como testigos. Estos se sembraron en la localidad de Darién en el primer semestre de 2004, en los dos tratamientos de fertilización, con dise o de bloques completos aleatorizados con tres repeticiones. El contenido de hierro y cinc en la semilla cosechada fue determinado por espectroscopia de absorción atómica. El análisis de varianza mostró diferencias significativas para la concentración de los minerales entre las variedades y entre los niveles de alta y baja fertilización con fósforo con promedios de 61,5 y 53,2 ppm, respectivamente, para hierro, y 26,3 y 23,1 ppm, respectivamente, para cinc. Teniendo en cuenta el análisis combinado para hierro y cinc a través de los dos tratamientos de fósforo, se sugiere que la aplicación de fósforo puede incrementar la concentración de hierro en la semilla, pero no la de cinc.
Diversification and Population Structure in Common Beans (Phaseolus vulgaris L.)
Matthew W. Blair,Alvaro Soler,Andrés J. Cortés
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0049488
Abstract: Wild accessions of crops and landraces are valuable genetic resources for plant breeding and for conserving alleles and gene combinations in planta. The primary genepool of cultivated common beans includes wild accessions of Phaseolus vulgaris. These are of the same species as the domesticates and therefore are easily crossable with cultivated accessions. Molecular marker assessment of wild beans and landraces is important for the proper utilization and conservation of these important genetic resources. The goal of this research was to evaluate a collection of wild beans with fluorescent microsatellite or simple sequence repeat markers and to determine the population structure in combination with cultivated beans of all known races. Marker diversity in terms of average number of alleles per marker was high (13) for the combination of 36 markers and 104 wild genotypes that was similar to the average of 14 alleles per marker found for the 606 cultivated genotypes. Diversity in wild beans appears to be somewhat higher than in cultivated beans on a per genotype basis. Five populations or genepools were identified in structure analysis of the wild beans corresponding to segments of the geographical range, including Mesoamerican (Mexican), Guatemalan, Colombian, Ecuadorian-northern Peruvian and Andean (Argentina, Bolivia and Southern Peru). The combined analysis of wild and cultivated accessions showed that the first and last of these genepools were related to the cultivated genepools of the same names and the penultimate was found to be distinct but not ancestral to the others. The Guatemalan genepool was very novel and perhaps related to cultivars of race Guatemala, while the Colombian population was also distinct. Results suggest geographic isolation, founder effects or natural selection could have created the different semi-discrete populations of wild beans and that multiple domestications and introgression were involved in creating the diversity of cultivated beans.
Development and diversity of Andean-derived, gene-based microsatellites for common bean (Phaseolus vulgaris L.)
Matthew W Blair, Monica Torres, Martha C Giraldo, Fabio Pedraza
BMC Plant Biology , 2009, DOI: 10.1186/1471-2229-9-100
Abstract: Robotics were used for high-throughput colony picking and to create a high-density filter of 18,432 double spotted cDNA clones which was followed by hybridization with repeat motif containing probes based on GA, CA, AAT, CAG, CAA and ACG repeats. A total of 1203 positive clones were identified by their addresses and sequenced from 5' ends and if required from 3' ends to confirm repeat motif and length. Out of 886 high quality sequences, 497 had complete microsatellite loci that were not truncated by the sequencing reaction and of these tri-nucleotide repeats were more common than di-nucleotide repeats. Different motifs were found in different frequencies in the 5' and 3' ends of the cDNAs. In a microsatellite development program, primers were designed for 248 SSR loci which were tested on a panel of 18 common bean genotypes to determine their potential as genetic markers finding higher average polymorphism information content for di-nucleotide repeat markers (0.3544) than for tri-nucleotide repeat markers (0.1536).The present study provides a set of validated gene-based markers for common bean that are derived from G19833, an Andean landrace that is an important source of disease and abiotic stress tolerance which has been used for physical map development and as a mapping parent. Gene-based markers appear to be very efficient at separating divergent wild and cultivated accessions as well as Andean and Mesoamerican genepools and therefore will be useful for diversity analyses and for comparative and transcript mapping in common bean.Microsatellites are molecular markers based on simple sequence repeat (SSR) loci that can be isolated from both coding and non-coding regions of the genome [1]. When SSR loci are located within or near genes their contraction and expansion can affect gene expression or lead to amino acid substitutions or knock-out mutation in open reading frames (ORFs) [2]. Gene-based microsatellites have been found at a predictable frequency in gene cod
Biofortified red mottled beans (Phaseolus vulgaris L.) in a maize and bean diet provide more bioavailable iron than standard red mottled beans: Studies in poultry (Gallus gallus) and an in vitro digestion/Caco-2 model
Elad Tako, Matthew W Blair, Raymond P Glahn
Nutrition Journal , 2011, DOI: 10.1186/1475-2891-10-113
Abstract: Maize-based diets containing the beans were formulated to meet the nutrient requirements for broiler except for Fe (Fe concentrations in the 2 diets were 42.9 ± 1.2 and 54.6 ± 0.9 mg/kg). One day old chicks (Gallus gallus) were allocated to the experimental diets (n = 12). For 4 wk, hemoglobin, feed-consumption and body-weights were measured.Hemoglobin maintenance efficiencies (HME) (means ± SEM) were different between groups on days 14 and 21 of the experiment (P < 0.05). Final total body hemoglobin Fe contents were different between the standard (12.58 ± 1.0 mg {0.228 ± 0.01 μmol}) and high Fe (15.04 ± 0.65 mg {0.273 ± 0.01 μmol}) bean groups (P < 0.05). At the end of the experiment, tissue samples were collected from the intestinal duodenum and liver for further analyses. Divalent-metal-transporter-1, duodenal-cytochrome-B, and ferroportin expressions were higher and liver ferritin was lower (P < 0.05) in the standard group vs. the biofortified group. In-vitro analysis showed lower iron bioavailability in cells exposed to standard ("Low Fe") bean based diet.We conclude that the in-vivo results support the in-vitro observations; biofortified colored beans contain more bioavailable-iron than standard colored beans. In addition, biofortified beans seems to be a promising vehicle for increasing intakes of bioavailable Fe in human populations that consume these beans as a dietary staple. This justifies further work on the large-seeded Andean beans which are the staple of a large-region of Africa where iron-deficiency anemia is a primary cause of infant death and poor health status.Iron (Fe) deficiency is the most common nutrient deficiency worldwide [1]. A major cause of Fe deficiency is low bioavailability from plant-based diets containing mineral absorption inhibitors such as polyphenols. Policies aimed to decrease Fe deficiency occurrence comprise primarily in the use of dietary iron additives for at-risk populations, food fortification, and diversification of diet
Diversidad de faseolinas en frijol común cultivado del Caribe
Blair,Matthew W.; Pantoja D,Wilfredo; Hidalgo,Rigoberto;
Acta Agronómica , 2007,
Abstract: in this study, 180 genotypes of cultivated phaseolus vulgaris from the caribbean were evaluated with the phaseolin marker. all the accessions belonged to the germplasm collection of the international center for tropical agriculture (ciat). beans from cuba were mostly s phaseolin (68.0 %) type, with small seed size, red and black seed color and type ii or type iii growth habit. these were followed by beans with t phaseolin (20.0 %) and finally by those with b, ch and sd phaseolin. in haiti , the most common phaseolin was t (48.1%), the majority of which were large seeded bush beans, mostly of the red mottled seed color class. many of the remaining accessions were s phaseolin (42.6%) and had small black seed, although a few had b, sb and sd phaseolin (4.6, 2.8 and 1.9% of genotypes, respectively). in puerto rico, t phaseolin was in the majority with 57.1%, most of these with large red or red mottled seed. s phaseolin was represented by 42.9 % of landraces some of which had small yellow, black or white seed. in the dominican republic , the t phaseolin was very abundant (85.7%) the majority of which were medium to large seeded bush beans all of which were red mottled. a smaller proportion of dominican landraces had s and b phaseolin (9.5% and 4.8% respectively). finally, in jamaica , t phaseolin was found for 40.0 % of the landraces, b phaseolin was equally common and 20% of the landraces had s phaseolin although this was based on a small sample of genotypes. the phaseolin patterns indicated the prevalence of both andean and mesoamerican beans in the caribbean.
Uso de selección asistida con marcadores para resistencia a antracnosis en fríjol común
Garzón,Luz Nayibe; Blair,Matthew W.; Ligarreto,Gustavo A.;
Agronomía Colombiana , 2007,
Abstract: the anthracnose caused by colletotrichum lindemuthianum is one of the most significant diseases in beans (phaseolus vulgaris l.) and can produce yield losses up to 95%. in this study, a breeding program utilizing molecular marker assisted selection (mas) was initiated. in order to obtain commercial colombian climbing beans resistant to c. lindemuthianum, the program incorporated genes co-5 and co-42taken from g2333, a resistant mesoamerican cultivar. from the crosses between g2333 and seven cultivated andean beans, were obtained progenies rc1f1. the cultivated andean beans included bola roja and rojo moteado types gathered from cundinamarca and boyacá crops. the bc1f1 plants were selected using the scars molecular markers sab3 and sas13 linked to co-5 and co-42 genes, respectively. in a genotypic evaluation of 1.271 rc1f1 plants, 608 and 603 were amplified with sab3 and sas13, respectively. the segregation expected ratio (1:1) in x2 tests was obtained for each molecular marker indicating x2 = 2,38, p = 0,12 for sab and x2 = 33,32, p = 0,07 for sas13. the amplification with both molecular markers was obtained in 299 plants bc1f1, according to the expected ratio (x2 = 1,11, p = 0,78) adjusted to the independent segregation. these plants were selected to continue the breeding program. in this study, a molecular marker assisted selection was implemented and introduction of resistant genes into commercially important colombian beans was accelerated.
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