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Accueil du site → Doctorat → États-Unis → 1994 → Performance, stability parameters, genetic effects, and prediction of performance in single, three-way, and double-cross hybrids of sorghum (Sorghum bicolor (L.) moench)

Texas A and M University (1994)

Performance, stability parameters, genetic effects, and prediction of performance in single, three-way, and double-cross hybrids of sorghum (Sorghum bicolor (L.) moench)

Ombakho, George Anthony

Titre : Performance, stability parameters, genetic effects, and prediction of performance in single, three-way, and double-cross hybrids of sorghum (Sorghum bicolor (L.) moench)

Auteur : Ombakho, George Anthony

Etablissement de soutenance : Texas A and M University

Grade : Doctor of Philosophy (PhD) 1994

Résumé
Trials were conducted in Texas, and in Kenya between 1990 and 1993 to evaluate performance and stability of single, three-way, and double crosses of grain sorghum, estimate genetic effects, and evaluate grain yield prediction methods for three-way hybrids. Grain yield heterosis was estimated for single and three-way crosses. Preliminary evaluations were at college station in 1990, and selected entries evaluated in four environments over two years in Texas. A complete set, excluding reciprocals, of parents, single, and three-way crosses, was evaluated in five environments in Kenya. Genetic effects were estimated from experiments in Kenya. In Texas, single and three-way crosses differed infrequently for characters studied, while these hybrid- types outperformed double crosses most times. Double crosses were most stable followed by three-way crosses, single crosses, and parental lines, respectively, for grain yield and other agronomic characters. In Kenya, three-way hybrids outyielded fertile single crosses in better environments, and the two hybrid-types showed equivalent performance in other agronomic characters. Sterile single crosses were superior to parental lines in all characters except threshing percentage. Three-way crosses were more stable than fertile single crosses. Better interpretation for yield stability came from logarithm transformed data. Within-plot variabilities, measured as standard deviations, for plant height, panicle length, and panicle exsertion were higher in three-way and double crosses, but differences were not large enough to be of agronomic importance. High-parent heterosis (heterobeltiosis) in single crosses was higher than in three-way crosses. Sterile single crosses exhibited significant heterosis, important for three-way hybrid-seed producers. Genetic analyses showed additive and dominance effects to be important in the expression of grain yield, threshing percentage, 1000-seed weight, days to 50% anthesis, plant height, panicle length, and panicle exsertion. However, for grain yield, epistatic effects also were important. Three-way hybrids grain yield was predicted using estimates of genetic effects. Correlation coefficients of observed and predicted values indicated relative effectiveness of five prediction methods to be in accord with significance of genetic effects included in the prediction equation. Prediction using means of nonparental single crosses was preferable because of its simplicity.

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