Use of a comprehensive breeding system for simultaneous improvement of yield and other traits in two erly-maturing maize populations
1999
Menkir, A. | Kling, J.G. (International Institute of Tropical Agriculture, Ibadan (Nigeria))
IITA adopted a comprehensive breeding system (CBS) to consolidate its earlier efforts and enhance efficiency by working in fewer elite breeding populations. Two early-maturing reciprocal composites, namely TZE COMP3 and TZE COMP4, were formed based on the heterotic patterns of source populations. These composites had undergone two cycles of selection using a reciprocal S1 testcross evaluation scheme. This study was, therefore, conducted at seven test environments to evaluate progress from selection. Inter-population testcrosses of randomly selected S1 lines from the original and improved selection cycles of the two composites were included in the study. The observed direct response to selection for grain yield of testcrosses was 5% per cycle. Selection also increased plant height, ear height, and days to silk by less than 5% per cycle. Significant improvement in plant and ear aspect as well as resistance to ear rot, leaf blight, leaf rust, and Curvularia leaf spot were detected in C1 and C2. The genetic variance among testcrosses for grain yield and six other agronomic traits were significant in the original (Co) and advanced (C2) cycles of selection. Average mid-parent heterosis for grain yield was 4% for Cl x Cl and 7% for C2 x C2 testcrosses. S1 lines derived from improved populations (C2) of the two composites produced the largest number of high- yielding testcrosses. Mean grain yields of ten C2 x C2 testcrosses exceeded that of a late maturing commercial single-cross hybrid by 13.5°%. These testcrosses were also comparable to the commercial hybrid for improved agronomic traits and resistance to diseases. The two composites have also been the sources of high-yielding open-pollinated varieties with broad adaptation across locations and countries in West and Central Africa. Since adequate genetic variability for the major agro nomic features is still present in the improved populations of these composites, further substantial improvements will be expected from the next cycles of reciprocal recurrent selection.
Afficher plus [+] Moins [-]Mots clés AGROVOC
Informations bibliographiques
Cette notice bibliographique a été fournie par International Maize and Wheat Improvement Centre
Découvrez la collection de ce fournisseur de données dans AGRIS