36 research outputs found

    Farmers’ Perceptions on Salinity Problems in Irrigated Fields in Kilosa District

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    Soil salinity contributes to one of the most serious ecological and environmental problems in most of the irrigation schemes in Tanzania. Understanding farmers’ perceptions of soil salinity and its effects on crop productivity is important in promoting soil and water conservation practices. A study was conducted in Chanzuru and Ilonga villages in Kilosa District in 2016 to determine farmers’ perceptions on soil salinity problems in the District. Therefore, a socio-economic survey was carried out on 60 respondents.  Data were collected using the semi-structured questionnaires. The data were analyzed using SPSS descriptive statistics and chi-square test. The finding of the study showed that farmers perceived salinity more on the basis of location than they did on the basis of socio-demographics.  The main causes of soil salinity as perceived by farmers were poor quality of irrigation water and poor drainage systems. Some socioeconomic and demographic characteristics that significantly influenced the farmers’ perceptions were sex and household size. The perceptions of farmers in the study area varied significantly from village to village, with their socio-demographic determinants. Farmers adapted the strategy of crop diversification and increase in farm size as a response to the problem of salinity occurring in their fields. Farmer perception on salinity should therefore be used as entry point by stakeholders to develop intervention programs that help to solve the problems occurring in the farmers’ fields. Key words: Salinity, farmers’ perception, problem confrontation index, crop diversification, irrigation water, scheme, sources of information, extension servic

    EVALUATION OF THE RESPONSES OF EIGHT RICE (Oryza sativa, L.) GENOTYPES TO VARIOUS CONCENTRATIONS OF NaCl IN A CONTROLLED ENVIRONMENT

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    Salinity is an ever increasing problem that reduces rice yield in many rice fields around the world. Developing salt tolerant rice (Oryza sativa L.) genotype is one of the solutions to the problem of salinity. This experiment was carried out in the Department of Crop Science and Horticulture at SUA to assess the salinity tolerance of 8 rice genotypes at the seedling stage. Ion accumulation in plants and dry matter content along with molecular markers were used to evaluate the tolerance of each rice genotype. The genotypes were IRRI 112, IRRI 124, FL 478, IRRI 113, IR65912-4B-10-3, IRRI 128, NERICA-L-19 and SUAKOKO-10. In this experiment, the genotypes were exposed to three salinity levels in a randomized complete block design arranged in factorial with three replications. The salinity levels were 100 mM NaCl, 50 mM NaCl and 0 mM NaCl. The homogenous mixture of sand, farm yard manure and rice husk (ratio of 6:2:10 respectively) was used as the planting medium for all rice genotypes. The soil texture was sandy clay-loam. The growth of the genotypes, ion accumulation and dry matter contents were significantly (p ‚ȧ 0.05) affected by increase in NaCl concentration. Two Saltol SSR markers (RM7075 and RM562) were used to determine the presence of salinity tolerance (saltol) gene in rice genotypes.¬† Based on the SSR markers, ion accumulation and dry weight of plants, two genotypes (IR65192-4B-10-3, and IRRI112) along with FL478 were selected as salt tolerant while two (IRRI-113 and IRRI-128) were moderately tolerant, and three (NERICA-19, SUAKOKO-10 and IRRI-124) were the most susceptible genotypes.¬† Therefore, two susceptible parents (NERICA-19 and SUAKOKO-10) were selected and two donor parents (FL478 and IR65192-4B-10-3) were selected. Keywords: salinity stress; NaCl concentration; genotypes; markers; seedling stage; Oryza sativa;

    HERITABILITY AND RELATIONSHIP BETWEEN DROUGHT TOLERANCE TRAITS AND YIELD IN GROUNDNUTS (ARACHIS HYPOGAEA L.) UNDER DIFFERENT WATERING REGIMES

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    A research article article was submitted to Asian J Agri Biol, 2016, volume 4Improvement of groundnuts for drought tolerance could increase production in drought prone areas.This study aimed at determining the heritability estimates and relationship of HI and SCMR with yield and yield components using 30 groundnut genotypes planted under different watering regimes, so as to speed up the selection and breeding of groundnut genotypes tolerant to drought. A completely randomized design arranged in a split plot experiment with four replications was conducted in screen house in Morogoro, Tanzania. Data collection was done on plant height, number of pod/plant and pod yield/plant. Drought tolerant traits measured included, harvest index (HI), SCMR at 40, 60 and 80 DAS. Broad-sense heritability was calculated for HI, pod yield, number of pod/plant and SCMR. Results showed that number of pods/plant, SCMR at 60 DAS and HI were significantly related to pod yield in all watering condition. Heritability of the traits ranged from 0.22 to 0.59 with HI having highest value and number of pods lowest in WW while in WS condition heritability was generally lower from 0.04 to 0.45. Due to SCMR at 60 DAS, number of pods/plant and HI having moderate heritability and significant correlation with pod yield under water stress condition, these could be useful criteria in drought tolerance selection

    Incorporation of resistance to angular leaf spot and bean common mosaic necrosis virus diseases into adapted common bean (Phaseolus vulgaris L.) genotype in Tanzania

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    Angular leaf spot (ALS) caused by the fungus Pseudocercospora griseola and Bean common mosaic and necrosis virus (BCMV/BCMNV) are important diseases of common bean in Tanzania that can cause severe yield reduction when uncontrolled. This study was conducted to incorporate resistant genes for ALS and BCMV/BCMNV diseases into adapted, market class and farmers and consumers preferred bean genotype using marker assisted selection. The parents Mexico 54 and UBR(25)95 donor of Phg-2 and I/bc-3 genes for ALS and BCMV/BCMNV, respectively were used for the recipient being Kablanketi. In selection, SCAR markers SNO2, ROC11 and SW13 linked to Phg-2, bc-3 and I gene, respectively were used. A parallel backcrossing (modified double cross) procedure was used. The F1, F2 and backcrosses from single crosses were characterized. The Chi square values for ALS were 0.081 (P<0.776) and 0.017 (P<0.896) and for BCMNV were 1.609 (P<0.205) and 1.2 (P<0.273) for molecular and phenotypic screening, respectively. The resistance to ALS and BCMNV was found to be monogenic and the genes involved are dominant and recessive, respectively. The heritability of ALS was found to be high (0.772) implying that selection for ALS can be done early in segregating populations. High correlation values, r = 0.741 and 0.624 for ALS and BCMNV, were obtained between phenotypic and molecular data, indicating high reliability for markers. In selection, it was possible to select lines with multiple disease resistances. This work signified the use of MAS for multiple gene screening.Keywords: Common bean, Pseudocercospora griseola, marker assisted selection, genotype, inheritanceAfrican Journal of Biotechnology Vol. 12(27), pp. 4343-435

    The role of genotype and production environment in determining the cooking time of dry beans (\u3ci\u3ePhaseolus vulgaris\u3c/i\u3e L.)

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    Dry bean (Phaseolus vulgaris L.) is a nutrient‚Äźdense food rich in proteins and minerals. Although a dietary staple in numerous regions, including Eastern and Southern Africa, greater utilization is limited by its long cooking time as compared with other staple foods. A fivefold genetic variability for cooking time has been identified for P. vulgaris, and to effectively incorporate the cooking time trait into bean breeding programs, knowledge of how genotypes behave across diverse environments is essential. Fourteen bean genotypes selected from market classes important to global consumers (yellow, cranberry, light red kidney, red mottled, and brown) were grown in 10 to 15 environments (combinations of locations, years, and treatments), and their cooking times were measured when either presoaked or unsoaked prior to boiling. The 15 environments included locations in North America, the Caribbean, and Eastern and Southern Africa that are used extensively for dry bean breeding. The cooking times of the 14 presoaked dry bean genotypes ranged from 16 to 156 min, with a mean of 86 min across the 15 production environments. The cooking times of the 14 dry bean genotypes left unsoaked ranged from 77 to 381 min, with a mean cooking time of 113 min. The heritability of the presoaked cooking time was very high (98%) and moderately high for the unsoaked cooking time (~60%). The genotypic cooking time patterns were stable across environments. There was a positive correlation between the presoaked and unsoaked cooking times (r = .64, p \u3c 0.0001), and two of the fastest cooking genotypes when presoaked were also the fastest cooking genotypes when unsoaked (G1, Cebo, yellow bean; and G4, G23086, cranberry bean). Given the sufficient genetic diversity found, limited crossover Genotype √ó Environment interactions, and high heritability for cooking time, it is feasible to develop fast cooking dry bean varieties without the need for extensive testing across environments

    The role of genotype and production environment in determining the cooking time of dry beans (\u3ci\u3ePhaseolus vulgaris\u3c/i\u3e L.)

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    Dry bean (Phaseolus vulgaris L.) is a nutrient‚Äźdense food rich in proteins and minerals. Although a dietary staple in numerous regions, including Eastern and Southern Africa, greater utilization is limited by its long cooking time as compared with other staple foods. A fivefold genetic variability for cooking time has been identified for P. vulgaris, and to effectively incorporate the cooking time trait into bean breeding programs, knowledge of how genotypes behave across diverse environments is essential. Fourteen bean genotypes selected from market classes important to global consumers (yellow, cranberry, light red kidney, red mottled, and brown) were grown in 10 to 15 environments (combinations of locations, years, and treatments), and their cooking times were measured when either presoaked or unsoaked prior to boiling. The 15 environments included locations in North America, the Caribbean, and Eastern and Southern Africa that are used extensively for dry bean breeding. The cooking times of the 14 presoaked dry bean genotypes ranged from 16 to 156 min, with a mean of 86 min across the 15 production environments. The cooking times of the 14 dry bean genotypes left unsoaked ranged from 77 to 381 min, with a mean cooking time of 113 min. The heritability of the presoaked cooking time was very high (98%) and moderately high for the unsoaked cooking time (~60%). The genotypic cooking time patterns were stable across environments. There was a positive correlation between the presoaked and unsoaked cooking times (r = .64, p \u3c 0.0001), and two of the fastest cooking genotypes when presoaked were also the fastest cooking genotypes when unsoaked (G1, Cebo, yellow bean; and G4, G23086, cranberry bean). Given the sufficient genetic diversity found, limited crossover Genotype √ó Environment interactions, and high heritability for cooking time, it is feasible to develop fast cooking dry bean varieties without the need for extensive testing across environments

    Pathogenic seedborne viruses are rare but Phaseolus vulgaris endornaviruses are common in bean varieties grown in Nicaragua and Tanzania

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    Common bean (Phaseolus vulgaris) is an annual grain legume that was domesticated in Mesoamerica (Central America) and the Andes. It is currently grown widely also on other continents including Africa. We surveyed seedborne viruses in new common bean varieties introduced to Nicaragua (Central America) and in landraces and improved varieties grown in Tanzania (eastern Africa). Bean seeds, harvested from Nicaragua and Tanzania, were grown in insect-controlled greenhouse or screenhouse, respectively, to obtain leaf material for virus testing. Equal amounts of total RNA from different samples were pooled (30-36 samples per pool), and small RNAs were deep-sequenced (Illumina). Assembly of the reads (21-24 nt) to contiguous sequences and searches for homologous viral sequences in data-bases revealed Phaseolus vulgaris endornavirus 1 (PvEV-1) and PvEV-2 in the bean varieties in Nicaragua and Tanzania. These viruses are not known to cause symptoms in common bean and are considered non-pathogenic. The small-RNA reads from each pool of samples were mapped to the previously characterized complete PvEV-1 and PvEV-2 sequences (genome lengths ca. 14 kb and 15 kb, respectively). Coverage of the viral genomes was 87.9-99.9%, depending on the pool. Coverage per nucleotide ranged from 5 to 471, confirming virus identification. PvEV-1 and PvEV-2 are known to occur in Phaseolus spp. in Central America, but there is little previous information about their occurrence in Nicaragua, and no information about occurrence in Africa. Aside from Cowpea mild mosaic virus detected in bean plants grown from been seeds harvested from one region in Tanzania, no other pathogenic seedborne viruses were detected. The low incidence of infections caused by pathogenic viruses transmitted via bean seeds may be attributable to new, virus-resistant CB varieties released by breeding programs in Nicaragua and Tanzania.Peer reviewe

    Seedling root architecture and its relationship with seed yield across diverse environments in \u3ci\u3ePhaseolus vulgaris\u3c/i\u3e

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    Seedling root phenotypes may have important impacts on fitness and are more easily measured than mature root phenotypes. We phenotyped the roots of 577 genotypes of common bean (Phaseolus vulgaris), representing the bulk of the genetic diversity for recent cultivars and landraces in this species. Root architectural phenotypes of seedlings germinated for nine days were compared to root architectural phenotypes in the field as well as seed yield across 51 environments with an array of abiotic stresses including drought, nutrient deficiency, and heat, as well as non-stress conditions. We observed repeatability ranging from 0.52‚Äď0.57 for measures of root phenotypes in seedlings, significant variation in root phene states between gene pools and races, relationships between seedling and field phenotypes, and varying correlations between seedling root phenes and seed yield under a variety of environmental conditions. Seed yield was significantly related to seedling basal root number in 22% of environments, seedling adventitious root abundance in 35% of environments, and seedling taproot length in 12% of environments. Cluster analysis grouped genotypes by their aggregated seedling root phenotype, and variation in seed yield among these clusters under non-stress, drought, and low fertility conditions was observed. These results highlight the existence and influence of integrated root phenotypes for adaptation to edaphic stress, and suggest root phenes have value as breeding targets under real-world conditions

    Seedling root architecture and its relationship with seed yield across diverse environments in \u3ci\u3ePhaseolus vulgaris\u3c/i\u3e

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    Seedling root phenotypes may have important impacts on fitness and are more easily measured than mature root phenotypes. We phenotyped the roots of 577 genotypes of common bean (Phaseolus vulgaris), representing the bulk of the genetic diversity for recent cultivars and landraces in this species. Root architectural phenotypes of seedlings germinated for nine days were compared to root architectural phenotypes in the field as well as seed yield across 51 environments with an array of abiotic stresses including drought, nutrient deficiency, and heat, as well as non-stress conditions. We observed repeatability ranging from 0.52‚Äď0.57 for measures of root phenotypes in seedlings, significant variation in root phene states between gene pools and races, relationships between seedling and field phenotypes, and varying correlations between seedling root phenes and seed yield under a variety of environmental conditions. Seed yield was significantly related to seedling basal root number in 22% of environments, seedling adventitious root abundance in 35% of environments, and seedling taproot length in 12% of environments. Cluster analysis grouped genotypes by their aggregated seedling root phenotype, and variation in seed yield among these clusters under non-stress, drought, and low fertility conditions was observed. These results highlight the existence and influence of integrated root phenotypes for adaptation to edaphic stress, and suggest root phenes have value as breeding targets under real-world conditions
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