Genetic variability and heterotic groups of Brazilian popcorn populations

Abstract

The development of successful advanced lines and cultivars in maize is dependent on parental selection and assignment to deWned heterotic groups. So, the objectives of this study were to evaluate genetic variability and identify heterotic groups among Brazilian popcorn varieties. Thus, diallel crosses of advanced generations of the popcorn hybrids, IAC 112 and Zélia, and of three open-pollinated popcorn varieties, RS 20, Branco, and SAM were performed. Ten hybrid combinations, the Wve parents, and Wve check treatments were arranged in a block design with four replicates in two tropical-zone locations (CWb climate). Both additive and non-additive eVects were important for grain yield, plant height, ear height, and husk cover. For popping expansion, only the additive eVects were important. Hybrid combinations between the local variety (Branco) and F 2 populations (IAC 112 and Zelia) resulted in the third and fourth highest values for popping expansion. The best grain yields were obtained with hybrid combinations involving SAM. Cultivars Zélia, IAC 112, and RS 20 increased popping expansion, whereas cultivar Branco increased grain yield of hybrid combinations. The following conclusions may be drawn: Brazilian popcorn populations have reduced heterosis and genetic variability to popping expansion in relation commercial cultivars; there is genetic variability among Brazilian popcorn populations that allows the exploitation of additive and nonadditive eVects for grain yield; it is possible to increase grain yield by using local varieties; but it would be diYcult to obtain commercial hybrids from local varieties because they have poor performance for popping expansion.

Effect of recurrent selection on the variability of the UENF-14 popcorn population

“…These results are in accordance with those obtained by Pereira and Amaral Júnior (2001), who employed the Design I (Comstock and Robinson 1948) in the initial studies of UENF-14. The high heritability estimates favors the hypothesis that the characteristic is oligogenic (Alexander and Creech 1977, Zanette 1989, Pacheco et al 1998, Coimbra et al 2001, Pereira and Amaral Júnior 2001, Miranda et al 2008. Except for the second cycle, in which there was reduction in the heritability estimate, there is a balance regarding the magnitude of values, confirming the predominance of additive genetic effects on the expression of the popping expansion (Scapim et al 2002, Simon et al 2004, Freitas Júnior et al 2009).…”

Inbreeding depression and genetic components for popping expansion and other traits in Brazilian populations of popcorn

“…The main objective in maize breeding programs is to obtain hybrids, and success depends on the choice of parents (Miranda et al, 2008; and optimization of the genotypes by environmental interaction (Miranda et al, 2009;Arnhold et al, 2009a). The value of homozygous inbred lines depends on how much of the variance can be reduced by inbreeding, and on how much the environmental variance will be affected by inbreeding (Wiegertjes et al, 1996).…”

“…The main feature of quality popcorn is its popping expansion volume (Mora and Scapim, 2007;Pereira et al, 2008), and there is evidence of the predominance of additive genetic variation for this trait (Dofing et al, 1991;Larish and Brewbaker, 1999;Miranda et al, 2008). Four quantitative trait loci (QTLs) on chromosomes 1S, 3S, 5S and 5L were found to explain 45% of the phenotypic variation in popping expansion (Lu et al, 2003).…”

Genetic control of grain yield and nitrogen use efficiency in tropical maize

“…Several reports in the literature described the use of diallel crosses to study the genetic control and determination of heterotic groups (Lee et al, 2005;Melani & Carena, 2005;Pswarayi & Vivek, 2007;Miranda et al, 2008). Through diallel analysis, it is possible to determine the additive and nonadditive effects in the genetic control of a particular characteristic.…”