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Accueil du site → Doctorat → États-Unis → 1990 → Evaluation of stability of performance of twenty-five diverse grain sorghum (Sorghum bicolor (L.) Moench) ; genotypes in Botswana

University of Nebraska - Lincoln (1990)

Evaluation of stability of performance of twenty-five diverse grain sorghum (Sorghum bicolor (L.) Moench) ; genotypes in Botswana

Mazhani, Louis Mulungisi

Titre : Evaluation of stability of performance of twenty-five diverse grain sorghum (Sorghum bicolor (L.) Moench) ; genotypes in Botswana

Auteur : Mazhani, Louis Mulungisi

Université de soutenance : University of Nebraska - Lincoln

Grade : Doctor of Philosophy (PhD) 1990

Résumé
Sorghum genotypes representing six types (parental lines, varieties, single-cross hybrids, topcross hybrids, composites and blends of varieties, hybrids, and topcrosses) were evaluated in a series of environments in Botswana in 1988-89. The specific objectives were : to examine and compare the relative average performance in grain yield and residue productivity of 25 genotypes consisting of six types ; estimate the stability parameters ; and identify superior genotypes based on the stability parameters.^ A randomized complete block design with six replications was used at each location. Data for yield and its related components were analyzed following two procedures described by Eberhart and Russell (1966) and Francis and Kannenberg (1978), respectively.^ Genotype x environment interaction was studied by partitioning the sources of variation in the combined analysis of variance into components representing comparison within and among sorghum types. A significant genotype x environment interaction was found, suggesting that a breeding program for Botswana should focus on the development of a number of genotypes, each adapted to some of these environments. Eleven genotypes were identified as desirable and therefore are worthy of special consideration both for commercial production and as parents for future breeding endeavors. Hybrids and their blend produced significantly higher yields than the other types. The hybrid blend was the most stable type based on a regression coefficient close to unity, deviations mean square close to zero, and a high mean yield. It is desirable for both the poor as well as favorable environments. In contrast, the currently recommended variety (V7) is expected to exceed the average performance only under low productive areas.^ Pairwise correlation coefficients in five environments showed that grain yield was significantly correlated to all the traits, indicating that differences in grain yield of genotypes relative to differences in the other traits were consistent across the environments. Correlation coefficients were consistently stronger in poor than good environments. There is thus room for the further genetic improvement of stability in sorghum. ^

Mots clés : Agronomy, Biological sciences

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