Heterotic parameterizations of crosses between tropical and temperate lines of popcorn

Abstract

ABSTRACT. We examined the heterotic parameterizations of diallel crosses among 10 popcorn inbred lines in two different environments (municipalities of Campos dos Goytacazes and Itaocara, Rio de Janeiro State) and originating from tropical, temperate and subtropical germoplasm. Traits, including grain yield (GY), plant height (PH), ear height (EH), days to silking (FL) and popping expansion (PE), were measured. The inbred lines and the hybrids were evaluated in a randomized complete block design with three replications. The sources of genotypic variation, inbred lines and heterosis had significant effects on all traits. When the sources of heterotic variation were compared separately, estimated mean heterosis was found to be significant for all traits. When inbred lines and specific heterosis was investigated, only popping expansion was not significantly different, demonstrating that heterotic effects are favorable for developing superior hybrids. A direct relation between ĝ i and i Vˆ was made clear, especially for traits that were slightly influenced by the effects of dominance. Additivity was determined to have the best effect for improving popping expansion. The hybrid combinations had positive estimates of heterosis for the GY but not for PE. The hybrids P 1 x P 3 and P 2 x P 4 had the best responses for the GY and PE. The superiority of the combination P1 x P3 shows that the addition of genomes with different edaphoclimatic adaptations is an important factor in obtaining superior hybrids.Keywords: Zea mays L., diallel crosses, yield and popping expansion.RESUMO. Parametrizações heteróticas de cruzamentos entre linhagens tropicais e temperadas de milho pipoca. O presente trabalho teve com objetivo averiguar as parametrizações heteróticas de cruzamentos dialélicos entre dez linhagens de milho pipoca oriundas de genótipos tropicais, temperados e semi-temperados, em dois ambientes (municípios de Campos dos Goytacazes e Itaocara, Estado do Rio de Janeiro), em relação às características rendimento de grãos; altura média de planta e da inserção da primeira espiga; número médio de dias para florescimento e capacidade expansão. As linhagens e os híbridos foram avaliados em delineamento em blocos ao acaso, com três repetições. Para as fontes de variação linhagens e heterose houve significância, pelo teste F, para todas as características. No desdobramento da fonte de variação heterose, estimativas de heterose média foram significativas para todas as características. Em relação à heterose de linhagens e específica, apenas a característica capacidade de expansão não expressou diferença significativa, o que confirma que os efeitos heteróticos não são favoráveis para síntese de híbridos com superioridade. A relação direta entre ĝ i e i Vˆ ficou claro, especialmente para as características pouco influenciadas pelos efeitos de dominância. O efeito gênico aditivo foi confirmado para capacidade de expansão. As combinações híbridas revelaram estimativas positivas de heterose para GY, mas não para PE. Os híbridos P 1 x P 2 e ...

Genetic progress in the UNB-2U population of popcorn under recurrent selection in Rio de Janeiro, Brazil

“…UENF has been operating since 1998, developing two research works: the use of recurrent selection in the UNB-2U population in order to obtain improved varieties (Pereira and Amaral, 2001;Daros et al, 2004;Santos et al, 2007;Freitas Júnior et al, 2009a;Amaral Júnior et al, 2010;Rangel et al, 2011) and the implementation of diallels to identify superior hybrids and parents for the formation of compounds (Freitas Júnior et al, 2006;Rangel et al, 2008;Silva et al, 2010Silva et al, , 2011.…”

Popcorn germplasm resistance to fungal diseases caused by Exserohilum turcicum and Bipolaris maydis

“…In this way, these are populations with high potential to be used as sources of resistance. Moreover, the consistent variability present between these populations -confirmed by the high genetic diversity estimates as estimated by ISSR markers (Amaral Júnior et al 2011) -make them even more interesting for the production of superior segregants.…”

“…Thirty-one genotypes were included in the group with the lowest means, with noteworthy values found for L71, L75, L76, P7, and PARA-172. In addition to these, (Silva et al 2011). The resistance of line P3 is possibly related to the fact that it originates from the genetically bred population CMS-42 (Pacheco et al 1998).…”

<b>Genetic parameter estimates and identification of superior white maize populations

“…These values demonstrated that these parents are promising in crosses for hybrids by raising the heterosis for GY. Silva, Amaral Jr, Gonçalves, Freitas Jr, and Ribeiro (2011) ). For VM and GP traits, ĥ i estimates were not presented because there was no significance in the diallel analysis.…”