Inbred Lines as Testers for General Combining Ability in Maize1
- B. T. Zambezi,
- E. S. Horner and
- F. G. Martin2
Inbred testers have been used successfully for the improvement of general combining ability (GCA) in maize (Zea mays L.), but they are not generally accepted as being equal to testers with a broad genetic base for this purpose. The objective of this study was to compare estimates of GCA obtained by use of the two tester types. Ten parents (nine S2 lines and the original population) from one population were crossed in a factorial design with a like set of parents from another population, and the resulting 100 crosses (10 involving each parent) were. tested at two locations. Significant estimates of GCA effects were obtained in both populations for grain yield, ear height, husk rating, and percentage erect plants at harvest. Specific combining ability (SCA) effect estimates were significant, but much smaller than those for GCA. Crossbred performance values for parents (testers) were compared by correlation analyses with predicted values based on GCA estimates for both parents. Correlation coefficients for the 18 inbred parents were similar to those for the two broad-base populations, which suggests that the former were in general as effective as the latter for ranking parents for GCA. These results provide further evidence that inbred testers can be used successfully for improving GCA as well as SCA in maize.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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