Assessment of Root Morphology as an Indicator of Drought Resistance in Common Bean (Phaseolus Vulgaris L.) PDF Download
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Author: Maurice D. Yabba
Publisher:
ISBN:
Category : Common bean
Languages : en
Pages : 424
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Author: Maurice D. Yabba
Publisher:
ISBN:
Category : Common bean
Languages : en
Pages : 424
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Author: Setegn Gebeyehu
Publisher: Cuvillier Verlag
ISBN: 3867270384
Category :
Languages : en
Pages : 131
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Author:
Publisher: CIAT
ISBN:
Category :
Languages : en
Pages : 60
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Author: Virginia Kapachika Chisale
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Common bean is one of the most important legume crops especially in developing countries like eastern and southern Africa. Though bean is important in these areas its production is affected by a number of abiotic stresses including low soil fertility and drought. However, in these countries the population growth rate is increasing therefore, there is need to find mechanisms to increase crop productivity. Previous studies on bean roots have shown that bean genotypes vary for root phenotypes, which enhance drought and low phosphorus tolerance. These traits include basal root whorl number, basal root number, adventitious roots, root etiolation, root growth angle and root hairs. These traits can be regulated by genes, by the environment or both. In Africa farmers have different preferences for different bean genotypes depending on color, seed size, resistant to stresses and maturity period. Hence in developing new bean cultivars, farmer's preferences should be taken into consideration. In this study we evaluated phenotypic variation for a number of root traits and their relation to phosphorus uptake. The genotypes which we evaluated in this study were first screened in another study, which evaluated bean genotypes for superior adaptation to low soil fertility and drought, this study was the Bean Improvement for Low Soil Fertility in Africa (BILFA) program. These genotypes were found to have varying performance under low soil fertility and drought. From that BILFA study we selected eleven genotypes to be used in our study and four non-BILFA genotypes making a total of fifteen genotypes. These non-BILFA lines are commercial cultivars in Malawi. Our study included both greenhouse and field experiments. The fifteen genotypes were phenotyped for root traits. Our data from the phenotyping study showed that the existing cultivars had less basal root whorl number compared to the BILFA lines. In an attempt to improve the adaptation of these cultivars to low phosphorus availability, we attempted to increase their basal root whorl number by hybridization between these commercial varieties, which have one whorl with four whorled genotypes.
Author: Amy Lydia Lasley
Publisher:
ISBN: 9781303014321
Category : Common bean
Languages : en
Pages : 116
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Author: Claire Verona Thomas
Publisher:
ISBN:
Category : Kidney bean
Languages : en
Pages : 210
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Author: George Samuel Abawi
Publisher: CIAT
ISBN: 9789589183144
Category : Beans
Languages : en
Pages : 128
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Major root rots of beans in Latin America and Africa; Minor root rots of beans in Latin America and Africa; Unreported root rots of beans in Latin America and Africa; Diagnosis of root rots in beans; Selected methodologies and techniques for research on root rots of beans; Management strategies for control of root rots of beans.
Author: Patrick Andrew Troy
Publisher:
ISBN:
Category :
Languages : en
Pages : 260
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Author: Jorge Carlos Berny Mier y Teran
Publisher:
ISBN: 9780355967524
Category :
Languages : en
Pages :
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Drought is the main constraint in common bean (Phaseolus vulgaris) production. Although breeding efforts to increase drought resistance have shown gains in productivity, their full potential remains untapped. Improvements have been limited by the complexity of the trait involved, limited germplasm recombination, and most importantly, the poorly understood genetic basis of tolerance. To gain information about the genetics and mechanism(s) of drought adaptation, I explored the genetic diversity of wild and domesticated Mesoamerican gene pool of the species through genetic analyses in natural, bi-parental, and multi-parental populations. In the first chapter, I evaluated root and shoot traits in a large panel of wild accessions and reference domesticated cultivars, both from the Mesoamerican distribution of common bean, in a greenhouse tube experiment. The domesticated beans were, in general, more vigorous and deeper-rooted than wild beans. Nevertheless, some wild beans were outstanding in their productivity and rooting capacity. A comparison of the measured phenotypic traits with the climatic and soil characteristics of the location of origin of the individual wild bean accessions showed that most traits were significantly associated with mean annual temperature and aridity. The most deeply rooted and productive accessions originated from the driest regions. Each wild accession was genotyped with both a SNP array and a GBS platform; three populations of wild bean accessions were identified, of which the most productive, deeply rooted, and more drought-tolerant population, originating from Central and North-West Mexico and Oaxaca. Through genome-wide association analyses, genomic regions associated with productivity, root depth, and drought adaptation were identified. Some co-located with regions showing signals of selection suggesting that drought stress is a driver of local adaptation in wild common beans.In the second chapter, I investigated the effects of drought stress on the genetic architecture of photosynthate allocation and remobilization in pods, one of the main mechanisms of drought resistance and overall productivity. A bi-parental recombinant inbred line (RIL) population of the Mesoamerican gene pool was evaluated in field conditions under well-watered conditions and terminal and intermittent drought stress in two years. There was a significant effect of the water regime and year on pod harvest index (PHI), a measure of the partition of seed biomass to pod biomass, its components, phenology and grain yield at the phenotypic and QTL level. QTLs for pod harvest index, including a major, stable QTL on chromosome Pv07 was detected. For grain yield, the QTLs were not stable; however, three were detected for the overall mean across environments. There was differential co-localization of the components of PHI, co-localizing mainly with either the pod wall, seed mass, or both. Three of the eight yield QTLs co-localized with PHI QTLs, underlying the importance of photosynthate remobilization in productivity. Epistasis explained a considerable part of the variation, especially for PHI and yield. In the third chapter, to further test the value of wild variation as compared with the domesticated forms, joint linkage mapping of nested populations was carried out in three newly develop domesticated by wild backcrossed recombinant inbred line populations. The populations were developed by crossing three wild accessions representing the extreme range of rainfall of the Mesoamerican wild bean distribution to an elite drought resistant domesticated parent. Grain yield was evaluated under field conditions in two fully irrigated trials in two seasons and a simulated terminal drought in the second season. The highest yielding populations were the populations from the lower part of the rainfall distribution. The populations were genotyped and a consensus map was developed containing 721 SNP markers. Twenty QTLs were found in 13 unique regions on eight chromosomes. At least one wild allele with a significant positive additive effect was found in five of these regions. The additive effects of all the QTLs ranged from -164 to 277 kg ha−1, with some evidence of allelic series. The variation explained by these QTLs ranged from 0.6 to 5.4 % of the total variation. These results underlie the potential of wild variation for bean crop improvement as well the identification of regions for efficient marker-assisted introgression and candidate genes.
Author: Walter H.. Burkholden
Publisher:
ISBN:
Category : Beans
Languages : en
Pages : 48
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