Evaluation of Synthetic Populations Developed from a Maize Variety (BSK) by Two Methods of Recurrent Selection¹

Abstract

The effectiveness of half‐sib selection with a doublecross tester and S 1 selection per se was evaluated following four cycles of selection in BSK (the Krug Hi I syn. 3 strain of ‘Krug Yellow Dent’). Five populations, BSK CO, BSK(HT)C2, BSK(S)C2, BSK(HT)C4, and BSK(S)C4, were selfed, sibbed, and crossed in a diallel series. They were also test‐crossed to four single‐cross testers The average of the four single‐cross testcross yields of the BSK (S) populations increased 10.6% during the four cycles, and the BSK(HT) populations increased 5.7%. The selfing series populations performed better than the testcross series populations when selfed, as indicated by a 38.7% increase for the BSK(S) bulk S 1 's compared with a 12.0% increase for the BSK(HT) bulk S 1 s. The populations per se increased 16.3% in the selfing series and 6.3% in the testcross series. The BSK(HT) × BSK(S) crosses exhibited heterosis, which indicated that the two methods developed populations that differed in gene frequency. This study has shown that the mean yield and the general combining ability of BSK were significantly improved by four cycles of selection with both methods of recurrent selection, but S 1 selection per se was more effective.