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  • 1
    Electronic Resource
    Electronic Resource
    Complementarity of genes for resistance to greenbug [Schizaphis graminum (Rondani)], biotype E, in sorghum [Sorghum bicolor (L.) Moench] (1991)
    Springer
    Theoretical and applied genetics 81 (1991), S. 105-110 
    Details
    ISSN: 1432-2242
    Keywords: Transgressive segregation ; Epistasis ; Frequency distribution ; Castle-Wright formula ; Number of effective factors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Gene complementarity among various sources of resistance to greenbug biotype E was assessed. Analysis of the F2 generation of crosses between susceptible and resistant parents (mating 1) and among sources of resistance (mating 2) suggested that resistance in sorghum to greenbug biotype E was complexly inherited and, to some extent, dependent on the nature of both the resistant and susceptible parents. Positive transgressive segregation in the F2 generations of both matings was found to be due to effective plus factors, contributed by both parents in a cross, which complemented each other. The number of plus factors ranged from one to two in the susceptible parents and from two to five in the resistant parents of mating 1, and from one to five in the parents of mating 2. The consistently significant reciprocal effects shown by Sarvasi and PI264453 indicated that these sources had major factors for resistance in their cytoplasms, which were expressed in all their crosses. The results from this study indicated that the sources of resistance complemented each other to give increased number of F2 segregates with increased resistance. Thus, it should be possible to increase and diversify resistance of sorghum to greenbug biotype E by accumulating different, effective plus factors from various sources through recurrent selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00226119
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  • 2
    Electronic Resource
    Electronic Resource
    Potential gain from selection for yield stability in two grain sorghum populations (1992)
    Springer
    Theoretical and applied genetics 85 (1992), S. 112-119 
    Details
    ISSN: 1432-2242
    Keywords: Sorghum ; Indirect selection criteria ; Yield stability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Maximum yield under highly unpredictable environments should be associated with selection of genotypes with superior performance across good and poor environments. Several stability parameters have been proposed to identify superior genotypes over a wide range of environments. None of these has been used as selection criteria, however, because of their low heritability. The objective of the study presented here was to compare the relative efficiency of predicted gain from indirect selection among three stability parameters: the coefficient of regression (b), deviation from regression (S d 2 ), and principal components scores (PC) from the AMMI model; two indices including mean yield and a stability parameter; and three indices involving yield at the best, the worst, and an intermediate environment. Two hundred S1 families from each of two sorghum populations (TP24D and KP9B) were evaluated at four dry-land evironments over 2 years. The low heritability estimates and the low genetic correlation between the various stability parameters and mean yield resulted in their low relative efficiency as indirect selection criteria for high yield across environments. However, when the parameters were combined with mean yield over all to create indices, the relative efficiency increased for all the environments. In terms of resource allocation, these indices were not as efficient as mean productivity, rank summation, and selection index that involved fewer environments in their estimation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00223853
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  • 3
    Electronic Resource
    Electronic Resource
    Comparisons of methods for introgressing exotic germ plasm into adapted sorghum (1994)
    Springer
    Theoretical and applied genetics 89 (1994), S. 233-239 
    Details
    ISSN: 1432-2242
    Keywords: Sorghum ; Introgression methods ; Exotic germ plasm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The incorporation of exotic germ plasm into breeding populations can broaden and diversify the genetic base of adapted genotypes. To more effectively utilize the genetic resources existing in Sorghum bicolor (L.) Moench, a rapid and efficient method of incorporating exotic genotypes into adapted populations is needed. Therefore, this study was conducted to compare the effectiveness of backcrossing to a broad-based population versus backcrossing to an inbred line for developing improved lines from adapted x exotic crosses. A wild sorghum, a cultivated landrace, and a converted sorghum line were crossed to an inbred line (CK60) and a broad-based population (KP9B). After two generations of backcrossing to the respective adapted parent, 50 F2 lines were derived from each of the backcross generations of every mating and evaluated at three test environments. Backcrossing to an inbred line (CK60) gave fewer high-yielding segregates and generated less genetic variation than backcrossing to a population (KP9B). Also, the number of agronomically acceptable lines derived from each CK60 mating was fewer than that derived from the corresponding mating with KP9B. Overall, the use of a broad-based population as an adapted recurrent parent for introgressing exotic genotypes may provide good opportunities for developing suitable inbred lines from adapted x exotic backcrosses.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00225147
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  • 4
    Electronic Resource
    Electronic Resource
    Assessment of genetic diversity in three subsets constituted from the ICRISAT sorghum collection using random vs non-random sampling procedures A. Using morpho-agronomical and passport data (2000)
    Springer
    Theoretical and applied genetics 101 (2000), S. 190-196 
    Details
    ISSN: 1432-2242
    Keywords: Key words Core collection ; Sorghum ; Morpho-agronomic diversity ; Sampling strategies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A large collection, such as the sorghum [Sorghum bicolor (L.) Moench] landrace collection held at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), represents a challenge for the maintenance of both the accessions of and the information documented for the germplasm collection. The accessibility and knowledge of the landrace collection are the essential factors for an efficient utilization of the genetic resources by both breeders and farmers. Different sampling strategies, either random or non-random, were proposed to obtain subsets of reduced size (core collection). Three subsets were established; a random sampling within a stratified collection (logarithmic strategy: L); a sample based upon morpho-agronomic diversity (principal component score strategy: PCS); and a sample based upon an empirical knowledge of sorghum (taxonomic strategy: T). Comparisons of these three samples for morpho-agronomic characterization and passport information were assessed to determine their impact on phenotypic diversity. For their overall diversity, the three subsets did not differ, as shown with the two-dimensional representation of the morpho-agronomic diversity and the Shannon-Weaver diversity indices. When comparisons for morpho-agronomic and passport data were considered, the PCS subset looked similar to the entire landrace collection. The L subset showed differences for characters associated with the photoperiod reaction that was considered in the stratification of the collection. The T subset was the most distinct from the entire landrace collection as it over-represented the landraces selected by farmers for specific uses and covered the widest range of geographical adaptation and morpho-agronomic characteristics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051468
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Assessment of Genetic Diversity in Three Subsets Constituted from the ICRISAT Sorghum Collection Using Random vs Non-Random Sampling Procedures B. Using molecular markers (2000)
    Springer
    Theoretical and applied genetics 101 (2000), S. 197-202 
    Details
    ISSN: 1432-2242
    Keywords: Key words Core collection ; Sorghum ; SSRs ; Genetic diversity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The large size of the sorghum [Sorghum bi-color (L.) Moench] landrace collection maintained by ICRISAT lead to the establishment of a core collection. Thus, three subsets of around 200 accessions were established from: (1) a random sampling after stratification of the entire landrace collection (L), (2) a selective sampling based on quantitative characters (PCS), and (3) a selection based on the geographical origin of landraces and the traits under farmers’ selection (T). An assessment was done of the genetic diversity retained by each sampling strategy using the polymorphisms at 15 microsatellite loci. The landraces of each subset were genotyped with three multiplex polymerase chain reactions (PCRs) of five fluorescent primer-pairs each with semi-automated allele sizing. The average allelic richness for each subset was equivalent (16.1, 16.3 and 15.4 alleles per locus for the subsets PCS, L, and T, respectively). The average genetic diversity was also comparable for the three subsets (0.81, 0.77 and 0.80 for the subsets PCS, L, and T, respectively). Allelic frequency distribution for each subset was compared with a chi-square test but few significant differences were observed. A high percentage of rare alleles (71 to 76% of 206 total rare alleles) was maintained in the three subsets. The global molecular diversity retained in each subset was not affected by a sampling procedure based upon phenotypic characters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001220051469
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