RESUMO A ocorrência da correlação negativa entre produtividade de grãos (PG) e capacidade de expansão (CE) no milho-pipoca contribui para dificultar o processo seletivo. No intento de contornar esse inconveniente, foi proposto, o caráter de importância, volume por pipoca expandida por hectare (VP). O objetivo deste estudo foi desenvolver o nono ciclo da população UENF-14 de milho-pipoca, estimar o efeito direto e indireto de VP e averiguar o progresso genéticos entre todos os ciclos seletivos. Duzentas progênies endogâmicas foram obtidas e avaliadas em blocos casualizados, com arranjos em repetições dentro de sets, sendo nove sets, oito constituídos por 25 progênies e um set com todos ciclos anteriores (oito) com três repetições. Avaliou-se a altura média da planta, prolificidade, peso de cem grãos, produtividade de grãos, capacidade de expansão e volume por pipoca expandida por hectare. Realizou-se a análise de trilha para desdobrar os efeitos diretos e indiretos e o índice de seleção Mulamba e Mock para seleção de quarenta progênies superiores. Houve variabilidade genética entre as progênies para todas características. Existe relação de causa e efeito entre o VP com a PG e CE, permitindo ganhos simultâneos com a seleção indireta. A seleção das progênies superiores com a utilização do peso atribuído por alternativas proporcionou maiores ganhos preditos de VP (20,73%). As médias obtidas em todos os ciclos indicaram aumentos, demonstrando a eficiência do uso da seleção recorrente em programas de melhoramento de milho-pipoca.

ABSTRACT The occurrence of negative correlations between grain yield (GY) and popping expansion (PE) in popcorn complicates the selection process. In an attempt to overcome this inconvenience, we proposed the use of the importance characteristic volume per popcorn per hectare (PV). The objectives of this study were to develop the ninth cycle of the UENF-14 popcorn population, to estimate the direct and indirect effects of PV and to verify the genetic progress among all selective cycles. We obtained and evaluated 200 inbred progenies in randomised blocks arranged in replicates within sets, with nine sets consisting of 25 progenies and one set with all previous eight cycles with three replicates. The average height of the plants, prolificacy, 100-grain weight, grain yield, grain popping expansion and volume per popcorn per hectare were evaluated. Track analysis was performed to determine the direct and indirect effects, and the Mulamba and Mock selection index was calculated for the selection of the 40 superior progenies. There was genetic variability among progenies in all evaluated traits, with a cause-and-effect relationship between PV with GY and PE, allowing simultaneous gains with indirect selection. The selection of the best progenies was more effective when using arbitrarily assigned weights, which provided higher predicted gains for PV (20.73%). The means obtained in all cycles indicated increases, demonstrating the efficiency of using continuous recurrent selection in popcorn breeding programs.

Abstract To date, no studies on the inheritance of Fusarium spp. ear rot resistance in popcorn are available. The purpose of this paper was to investigate the additive-dominance model to estimate the genetic components of variance, heritability and the inheritance pattern in a diallel for popcorn, by Hayman’s approach. The experiment was carried out in two environments, using eight parent lines. The following traits were measured: grain yield (GY), popping expansion (PE), incidence of ears infected by Fusarium (FusIE), total number of kernels infected by fungi (FunIK) and total number of kernels infected by Fusarium spp. (FusIK). The results indicated that the incidence of FusIK (Fusarium-infected kernels), FunIK (fungus-infected kernels), and FusIE (Fusarium-infected ears) is controlled by dominant genes. Parent L77 had a high number of favorable alleles for all resistance-related traits, as well as for PE. The strategy recommended for reduction of FunIK, FusIK, and FusIE consists of exploiting hetorosis using inbred lines with favorable alleles.

RESUMO. O êxito de qualquer programa de seleção recorrente depende da variabilidade genética da população avaliada, sendo utilizada para se referir à diversidade de alelos existentes nos vários locos genéticos. Assim, o objetivo do presente estudo foi investigar o impacto da seleção recorrente em nove ciclos da população UENF-14 de milho-pipoca através da análise da diversidade genética e da estrutura utilizando marcadores microssatélites (SSR-ESTs). O DNA genômico foi extraído de folhas jovens de 25 indivíduos de cada ciclo (C0, C1C2, C3, C4, C5, C6, C7 e C8) totalizando 225 amostras da população UENF-14. Para a análise da diversidade genética entre os ciclos de seleção recorrentes foram utilizados cinquenta marcadores SSR-ESTs, dos quais 16 revelaram ser polimórficos. Trinta e quatro alelos foram detectados, com uma média de 2,13 alelos por locos. Ao longo de todos os ciclos de seleção recorrentes houve uma redução na heterozigosidade e aumento na endogamia. A estrutura da população mostrou um compartilhamento de alelos inferindo que alguns podem ser direcionados para as principais características de seleção.

ABSTRACT. The success of any recurrent selection program depends on the genetic variability of the evaluated population, which is used to refer to the diversity of existing alleles at many genetic loci. Thus, the goal of the present study was to investigate the impact of recurrent selection across nine cycles of a UENF-14 popcorn population through the analysis of genetic diversity and structure using microsatellite markers (EST-SSRs). Genomic DNA was extracted from young leaves of 25 individuals from each cycle (C0, C1 C2, C3, C4, C5, C6, C7, and C8), totaling 225 samples from the UENF-14 population. Fifty EST-SSR markers were used for the analysis of genetic diversity across the recurrent selection cycles, 16 of which were polymorphic. Thirty-four alleles were detected, with an average of 2.13 alleles per locus. Throughout all the recurrent selection cycles, there was a reduction in heterozygosity and an increase in inbreeding. The population structure showed a sharing of alleles, inferring that some may be directly related to the main selection characteristics.

When it comes to recommending sorghum (Sorghum bicolor) cultivars, it is essential to carry out a genetic evaluation of the agronomic traits of promising genotypes from several common environments where the crop is cultivated. This study consisted of a genetic evaluation of 52 experimental grain sorghum hybrids and eight commercial cultivars. Hybrids were evaluated in 19 experiments representing the most varied cultivation conditions in Brazil. Traits of agronomic interest such as grain yield, flowering and plant height were analysed. Genotypic evaluation was performed following the REML/BLUP (Restricted Maximum Likelihood/Best Linear Unbiased Predictor) procedure; the MHPRVG (Harmonic Mean of Relative Performance of Genotypic Values) method was also employed to study stability and adaptability. Hybrids which stood out in terms of highest grain yield based on genotypic values, stability and adaptability were 0306037, 1G150, DKB 599, 0306039, 1G282 and 0307671. Of these, only 1G282 showed restrictions as to plant height. For flowering, experimental hybrids showed shorter cycles than commercial cultivars, confirming the efficiency of genetic improvement for this trait. With the analysis of grain yield considering days to flowering and plant height as covariates, it was observed that most of the hybrids of greater performance, showed grain yield to be positively influenced by plant height and days to flowering.