S1 Selection in Honeycomb Design for the Improvement of High Yield Maize (Zea mays L.) Inbreds and Hybrids

Abstract

Selection within Syn1 population of maize resulted in genetic equilibrium of selected population within 1 or 2 cycles of selection. High yield level could be obtained in a faster rate when improvement was applied in a narrow base population from adapted germplasm as compared with broad base population from unadapted germplasm. S1 and testcross selection which selected for high yield and high combining ability inbreds, respectively required 3 planting seasons per cycle. In order to improve the efficiency of selection, alternate S1 and diallel selections which required only 2 planting seasons per cycle was proposed. Inbred extraction from heterogeneous population for high yield inbreds under competitive environment by pedigree selection rendered the inconsistent results. Therefore, inbred selection under nil-competition to ensure full expression of genotypes in early generations should increase the efficiency of pedigree selection for high yield inbreds. Good hybrids could derive from high yield and/or high combining ability inbreds. However, high yield inbreds are preferable over the high combining ability but low yield inbreds, especially when commercial single cross hybrid is the ultimate goal of the program.