Genetic Variances in Populations Developed from Full‐Sib and S 1 Testcross Progeny Selection in an Open‐Pollinated Variety of Maize 1

Abstract

A nested Design I consisting of full-sib and half-sib families was used to study changes in genetic variances resulting from two selection systems in the ‘Krug’ yellow dent variety of maize (Zea mays L.). Two populations derived from Krug on the basis of earlier Design I experiments were used. K (S1) syn-2 was developed by intercrossing S1 progenies of the male parent of selected half-sib families. The second population, K (FS) syn-2 was developed by intercrossing remnant seed of selected full-sib progenies. Both selected populations, K (FS) syn-2 and K (S1) syn-2, were significantly higher yielding than the original variety, Krug. Design I matings were made within each of the two selected populations to provide evidence on changes in genetic variances that had occurred from the selection practiced. Selection resulted in a moderate decrease in genetic variance, with S1 progeny and full-sib selection producing, apparently, different changes in magnitude of genetic variances