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 ...

Elephant grass is a plant of tropical origin with high biomass-production potential that stands out today as an alternative energy source. The potential of its genotypes depends on the genotype × environment interaction. The objective of this study was to estimate the genotype × environment interaction and compare stability methods in elephant grass for biomass production in a biannual cutting regime. The experiment was conducted in a randomized block design with two replicates and evaluations of 73 elephant-grass genotypes in six cuts. The trait dry matter yield was utilized for the analysis of the genotype × environment interaction and the stability. The stability analysis methods employed were those of Yates and Cochran, Plaisted and Peterson, Wricke, Annicchiarico, Lin and Binns, and Huehn. Kang and Phan's ranking was adopted for all the methods. Spearman's coefficient was utilized to evaluate the degree of agreement between the different methods employed. Significant differences were observed for the genotype × environment interaction. Non-parametric Lin and Binns' and Annicchiarico's methods were more discriminating than the analysis of variance methods in the evaluation of stability and productivity of the tested genotypes.

-The purpose of this study was to quantify the genetic diversity among popcorn genotypes on the market and in

da silVa lédo 4 , FláVio dessaune taRdin 5 , max campos de souza 6 1 Recebido para publicação em 23/11/13. Aceito para publicação em 25/03/14.

ABSTRACT. The purpose of this study was to evaluate the interaction between genotypes and environments, evaluate adaptability and stability, and study the relationship between genetic structure and homeostasis. In addition to landrace, the study evaluated recommended genotypes or genotypes in experimental recommendation stages (varieties and hybrids) in three environments in northern and northwestern Rio de Janeiro State. Eight traits were measured, including grain yield and popping expansion. The individual analysis of variance revealed significant differences for all traits at 1% probability. In the combined analysis of variance, the genotype by environment interaction was significant at 1% probability for all traits except ear height. The interaction was simple for all traits except mean number of ears. The method of Lin and Binns detected the most suitable and stable genotypes, and also the most productive. UNB2U-C4 and IAC112 contained the lowest values of general P i . Of those, UNB2U-C4 contributed least to the interaction, and IAC112 ranked fourth in interaction. UNB2U-C4 stood out with the best adaptation to favorable and unfavorable environments. No association between the genetic structure and stability degree in popcorn was observed.Key words: Zea mays, genotype interaction by environment, phenotypic stability.RESUMO. Estatística P i na avaliação da adaptabilidade, estabilidade e relação da estrutura genética e homeostasia em milho pipoca. Objetivou-se avaliar interação entre genótipos por ambientes, avaliar adaptabilidade e estabilidade, bem como estudar a relação entre estrutura genética e homeostasia. Além de raças, foram avaliados genótipos recomendados ou em fase de recomendação no Brasil (variedades e híbridos) em três ambientes no Norte e Noroeste Fluminense. Foram quantificadas oito características, incluindo rendimento de grãos e capacidade de expansão. A análise de variância individual revelou diferenças significativas, a 1% de probabilidade de erro, para todas as características avaliadas. Pela análise de variância conjunta, com exceção da variável altura de espiga, houve interação significativa, a 1% de probabilidade, entre genótipos e ambientes. Excetuando-se número médio de espigas, as demais características expressaram interação do tipo simples. O método de Lin e Binns revelou os genótipos mais adaptados e estáveis, os quais foram também, os mais produtivos. UNB2U-C4 e IAC112 contiveram os menores valores de P i geral. Desses, UNB2U-C4 conteve o menor percentual de contribuição para a interação e IAC112 foi o quarto genótipo a contribuir para a interação. UNB2U-C4 sobressaiu-se com a melhor adaptação a ambientes favoráveis e desfavoráveis. Houve ausência de associação entre estrutura genética e grau de estabilidade em milho pipoca.Palavras-chave: Zea mays, interação genótipos por ambiente, estabilidade fenotípica.