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  • 1
    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
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 85 (1992), S. 112-119 
    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
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