INBREEDING IN A MAIZE SYNTHETIC OF SELFED-SIB FAMILIES (S1 LINES)

Abstract

Synthetics are genetically improved populations for farmers that cannot buy hybrid seed. In this paper, inbreeding is calculated for a maize synthetic (Zea mays L.) created with selfed-sib families (AH) or S₁ lines. The synthetic is obtained from the first generation by open pollination of a balanced composite made with the families. Inbreeding in the first generation is calculated through an equation that includes several generations: F(AH)₁ = (1/4nm)[(2m + 1) + 4 m(n – 1)F₁ + 2(m – 1)F₀ + F_-1], where n is the number of families, m the number of plants per family, and F is the inbreeding coefficient which sub-indexes are the generation numbers. After elimination of the terms with zero inbreeding in the recurrent equation , inbreeding in an F₁ synthetic with 10 families and 10 plants per family is equal to 0.0526. The number of families affects more the synthetic inbreeding than the number of plants per family.