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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 74 (1987), S. 310-316 
    ISSN: 1432-2242
    Keywords: Stability variance ; Genotype x environment interaction ; Adaptation ; Saccharum ; Sugarcane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The stability-variance statistic, ĝs i 2 , measures the contribution of the ith genotype to genotype x environment interaction. In addition to the knowledge of cultivar stability for an agronomic trait, information on whether stability of one trait can be used to predict stability of another should be useful to breeders. Three separate groups of data, respectively involving CP 79 series, CP 80 series, and CP 81 series experimental clones of sugarcane (Saccharum spp.) were used in this study. Rank-correlation coefficients (rs) between ranks of genotypes for ĝs i 2 's for paired traits indicated in both plant-cane and ratoon crops that stability of tons per hectare of sugar can be predicted from the stability of tons per hectare of cane (THC) and also, to a lesser extent, from the stability of stalk number. The stability of THC also can be reasonably well predicted from the stability of stalk number. Brix stability may give some indication of the stabilities for percentage sucrose and sugar concentration (SC). The ĝs i 2 's for percentage sucrose and SC were almost identical in the CP 79 and CP 81 series (rs varied from 0.93, P〈0.01, in plant-cane crop for CP 79 series to 0.98, P〈0.01, in plant-cane crop for CP 81 series). Whether correlations were based on ĝs i 2 's estimated across locations within crops or across crops, the magnitude of rs was about the same. Means of various traits were not correlated with their respective ĝs i 2 's (for CP 81 series), indicating that identification and selection of high-yielding sugarcane genotypes with a relatively high degree of stability of performance across test environments should be possible.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Theoretical and applied genetics 81 (1991), S. 162-165 
    ISSN: 1432-2242
    Keywords: Genotype x environment interaction ; Stability ; Maize ; Zea mays ; Heterogeneity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Genotype x environment (GE) interaction encountered in experiments complicates genotype selection and varietal recommendation. The integration of yield and stability of genotypes into a single parameter may make selection and recommendation easier. Kang developed a rank-sum method that allows selection for both yield and the stability variance statistics (σ i 2 or s i 2 ) of Shukla. The objective of this research was to compare the rank-sum selection method to selection based on yield alone in five international maize (Zea mays L.) yield trials. Ranks were assigned for yield (the highest mean yield received a rank of 1) and for σ i 2 and s i 2 (the lowest value received a rank of 1). The yield and σ i 2 ranks and/or the yield and s i 2 ranks for each genotype were summed. Each trial contained two reference entries (REs). Yield rank or rank-sum of each genotype was compared to yield rank or rank-sum of the best RE (BRE). GE interaction was significant for all trials. Heterogeneity in the GE interaction due to the linear effect of a covariate (differences in fertility and/or cultural practices) was significant in Trials 1, 2, and 5. Overall, in all trials, 29 genotypes were selected on the basis of yield alone. On the basis of σ i 2 and yield rank-sum, 32 genotypes were identified, with 11 being lower yielding than the 29 yield-based selections. On the basis of s i 2 and yield rank-sum, 31 genotypes were selected, with 11 being lower yielding than the yield-bases selections. Obviously, yield is sacrificed when the rank-sum method is used in the selection process. However, selection based on yield alone may not be adequate when GE interaction is significant because of testing in diverse environments.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 48 (1990), S. 63-72 
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; corn ; yield ; kernel weight ; shelling percentage ; plant height ; ear height ; husk weight ; cob weight
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary White-endosperm (y y y) maize (Zea mays L.) is vital to the maize dry-milling industry. However, a substantially greater acreage in the U.S.A. is planted to yellow (Y Y Y) than white maize. Data on comparative performance of yellow and white maize is scanty, and results are inconclusive. This field study was conducted to provide information on dosage effects of y gene on grain yield, 500-kernel (K) weight, shelling percentage, plant and ear height, and cob weight. Yellow x yellow, yellow x white, and white x white endosperm crosses were made among five yellow and five white endosperm lines of Mo14W × Oh7B parentage. In the material studied, the genetic complement of the white-endosperm parent Mo14W varied from 12.50% to 87.50% across 15 treatments. The effect of Mo14W dosages among treatments was removed through analysis of covariance. If differences among treatment means existed, they were attributed to the y gene. A test of parallelism among regression coefficients (Ho. β1=β2=---β15=βc) indicated that these regressions coefficients for plant height, ear height, 500-K weight, and husk weight showed parallelism across yellow x yellow, yellow x white, and white x white crosses. Differences in plant height were significant in 3 out of 5 comparisons each between Y Y vs. y y, Y y vs. y y, and Y Y vs. Y y. Differences in ear height were significant in 1 of 5 Y Y vs. y y comparisons, in 3 of 5 Y y vs. y y comparisons, and in 1 of 5 Y Y vs. Y y comparisons. Differences in 500-K weight were significant in 4 of 5 Y Y vs. y y, in 2 of 5 Y Y vs. Y y and in 1 of 5 Y y vs. y y comparisons. Differences in husk weight were significant in all the Y Y vs. y y comparisons, in 4 of 5 Y y vs. y y comparisons, and in 1 of 5 Y Y vs. Y y comparisons. An increase in the y gene dosage caused, in general, a significant decrease in grain yield, 500-K weight, plant height, ear height, and husk weight. Shelling percentage was decreased but not appreciably. The Y y combination had a heterotic effect on plant height, ear height, and cob weight. An implication of the findings of this study is that it would be difficult to breed for high-yielding white maize if one used this y gene source. At this time, this is the only source (chromosome 6) available for white-endosperm maize. Non-parrallelism among regression coefficients was noted for shelling percentage, grain yield, and cob weight. Non-parallelism was observed in shelling percentage of the yellow x yellow crosses, cob weight of the yellow x white crosses and in grain yield of both yellow x yellow and yellow x white crosses. In general, an increase in mean Mo14W dosage resulted in increased grain yield. Mo14W dosages generally reduced cob weight in the yellow x white crosses. Shelling percentage increased as the mean Mo14W dosages increased for the yellow x yellow crosses. An increase in Mo14W dosages resulted in an increase in 500-K weight.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Euphytica 51 (1990), S. 19-23 
    ISSN: 1573-5060
    Keywords: Zea mays ; maize ; corn ; Aspergillus flavus ; Aspergillus parasiticus ; aflatoxin ; resistance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Contamination of maize (Zea mays L.) grain prior to harvest with aflatoxin frequently occurs in the southern U.S.A. and sources of resistance are needed. Maize from twelve genotypes (varieties) crossed to two testers was analyzed for aflatoxin B1 (AFB1) contamination at Baton Rouge, LA and Tifton, GA in 1987. Variety Philippines had the lowest amount of AFB1 at Baton Rouge and one of the lowest amount of AFB1 at Tifton. In the combined analysis of variance, the location x treatment x tester x variety interaction was significant. This interaction was analyzed and a stability variance (σ1 2) statistic calculated. Mean AFB1 accumulation and stability of AFB1 production were examined simultaneously, i.e., variety ranks for AFB1 and σ1 2 were summed. The most desirable (lowest rank sum) variety across locations, testers, and treatments (inoculation and control) was St. Charles White, followed by Delta Prolific White, and Hopi. The most inconsistent AFB1 accumulation, along with high AFB1, was on Fino, Atkinson, USAWI, Navajo, and Michoacan-21. The ranks of varieties between the inoculation and control treatments were different (rs=−0.51 for Baton Rouge and 0.29 for Tifton). The rs (rank correlation coefficient) for the control treatments between Baton Rouge and Tifton was 0.60 (P〈0.05) and that for the inoculation treatments was −0.20. The varieties identified in this study as having relatively low concentration of AFB1 should be useful to maize breeders in reducing AFB1 contamination in field maize.
    Type of Medium: Electronic Resource
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