Potencial de híbridos simples de milho para extração de linhagens

Abstract

Populations derived from commercial single hybrids are one of the breeder options for inbred line extraction because of their adaptation and probable high frequency of loci with fixed favorable alleles. Even the segregating loci carry favorable alleles at a frequency of 0.5. Therefore, identification of promising single hybrid populations for inbred line extraction is strategic to increase the efficiency of breeding programs. The populations derived from the two commercial single hybrids AG9012 and C333 were assessed to estimate their capacity to inbred line extraction using the genetic and phenotypic parameters estimate, the m+a estimate and Jinks & Pooni (1976) methodology. Two sets of 169 S1 families derived from each hybrid population were assessed during the 1999/2000 growing season in the experimental area of the Biology Department at UFLA in Lavras, MG. The families were assessed in two simple 13 x 13 lattices in 3 m single row plots. The assessed traits were: a) incidence of Phaeosphaeria maydis in two sowing periods; b) plant height; c) ear height; and, d) de-hulled ear yield. It was detected that inbred lines with good "per se" performance can be obtained. The C333 hybrid derived population was the most promising for breeding purposes due to its resistance to Phaeosphaeria maydis associated with a higher mean and greater potential to generate superior inbred lines. The Jinks & Pooni (1976) methodology gave more informations to help the population choice than the m+a estimate. However, when it's possible, both can be used together to help the plant breeders to make a choice.