A B S T R A C TSorghum bicolor (L.) (Moench), which stands out for dry matter yield per hectare, has been considered as potential raw material for biofuels and electricity generation. It has a production cycle of six months, possibility of mechanization of cultivation and harvest and good adaptation to most regions of Brazil. Sorghum genotypes were evaluated for agronomic potential and chemical composition favorable to the production of second-generation ethanol. Three brown midrib (bmr) sorghum mutant hybrids were compared to three conventional hybrids. The bmr sorghum mutant hybrids are associated with reduced lignin content, making these genotypes more promising to the enzymatic conversion processes of the biomass. Sorghum biomass showed a high potential in terms of biomass production, with an average dry matter yield of 26.57 Mg ha −1 . Brown midrib sorghum hybrids showed significantly lower lignin contents than conventional hybrids and demonstrated the potential for cellulosic ethanol production.

In view of the narrow genetic base of popcorn, probably due to its evolution by selection from flint maize types alone, knowledge about genetic divergence is imperative for the formation of heterotic groups. Thus, our objective was to identify heterotic groups of popcorn lines; we did so by exploiting the representative genotype collection of the Active Popcorn Germplasm Bank of the State University of Northern Rio de Janeiro. Thirty-eight popcorn genotypes from different origins were analyzed by two methodologies to identify divergent groups. In the first method, the genotypic data were processed to determine the number of groups, based on Bayesian clustering algorithms, and two clustering methods (UPGMA and Ward), based on three genetic distance algorithms, weighted index, unweighted index, and an index of genetic distance or dissimilarity, proposed by Smouse and Peakall. The second methodology identified groups based on simultaneous use of morphoagronomic and molecular information and extracting the genetic distance matrix by the Gower algorithm, and later applying UPGMA and Ward clustering methods. The consistency of the clustering methods was evaluated by cophenetic correlation coefficients. The significance of these coefficients was examined by the Mantel test. There was significant genetic variability among corn popcorn accesses at morphological and molecular levels. There also ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 17 (3): gmr18083 C. Vittorazzi et al 2 was agreement between multivariate clustering techniques, mainly when using genotypic data provided by microsatellite markers. heterotic groups were identified; these were formed mainly according to the origin of each genotype and/or geographic origin. We found that there is sufficient heterosis to develop new cultivars.

-Recurrent selection can generate successive gains for characters of economic interest without causing genetic narrowing in the population. However, it has rarely been used in breeding programs in popcorn, especially when using full-sibling progenies to generate more expressive gains. The objective of this study was to estimate the genetic gain of the UENF-14 popcorn population through recurrent selection, and verify the evolution of the gains between the selection cycles four and eight. A total of 200 full-sibling progenies were evaluated in randomized blocks arranged in eight sets within three replicates in two environments; each set containing twenty-five progenies and six controls (selection cycles 4, 5, 6 and 7 of the UENF-14, BRS-Angela and IAC-125). The average height, prolificacy, 100-grain weight, ear weight, grain yield, and grain popping expansion of the plants were evaluated. In the selection of the thirty superior progenies for the eighth cycle, the Mulamba and Mock selection index was used, which generated estimated genetic gains of 4.60 for grain yield and 3.61% for popping expansion. The grain yield increased 111.99 kg ha -1 and the popping expansion increased 1.75 mL g -1 per cycle. The evolution of the cycles resulted in an accumulated genetic gain for the main characters of economic importance, allowing the prediction of success in the continuity of the recurrent selection.Keywords: Selection index. Recurrent selection. Zea mays L.. GANHOS GENÉTICOS E AVANÇOS SELETIVOS NA POPULAÇÃO UENF-14 DE MILHO-PIPOCARESUMO -A seleção recorrente embora permita sucessivos ganhos para caracteres de interesse econômico, sem provocar estreitamento genético na população, tem sido raramente utilizada em programas de melhoramento com milho-pipoca, sobretudo em se tratando da estratégia de utilização de progênies de irmãos-completos, em que são possíveis ganhos mais expressivos. O objetivo deste estudo foi estimar o ganho genético na população UENF-14, de milho-pipoca, por meio de seleção recorrente e averiguar a evolução dos ganhos entre os ciclos quatro e oito de seleção. Foram avaliadas 200 progênies de irmãos-completos, em blocos casualizados, com arranjos em sets dentro de três repetições em dois ambientes, no total de oito sets, sendo que cada set continha vinte e cinco progênies e seis testemunhas (ciclos 4, 5, 6 e 7 de seleção em UENF-14, BRS Angela e IAC 125). Avaliou-se a altura média da planta, prolificidade, peso de cem grãos, peso de espiga, produtividade de grãos e capacidade de expansão. Na seleção das trinta progênies superiores para o oitavo ciclo, foi utilizado o índice de seleção Mulamba e Mock, que proporcionou ganhos genéticos estimados de 4,60 e 3,61%, respectivamente, para produtividade de grãos e capacidade de expansão. Houve incremento de 111,99 kg ha -1 e de 1,75 mL g -1 , por ciclo, para a produtividade de grãos e capacidade de expansão, nesta ordem. A evolução dos ciclos revelou ganho genético acumulado para os principais caracteres de importância econômica da cultura, possibil...

Polysora rust, caused by Puccinia polysora, is one of the most economically important foliar diseases of maize, and the use of resistant genotypes is the most efficient and economically appropriate measure to control this disease. In popcorn, damage caused by this disease is equivalent to that found in common maize. However, studies on the identification of sources of resistance in popcorn are much more scarce. This study aimed to evaluate the reaction of popcorn genotypes regarding polysora rust resistance. For this purpose, 37 temperate and tropical popcorn genotypes were evaluated in randomized block experiments with four replicates in two crop seasons, in Campos dos Goytacazes, RJ, Brazil. Disease intensity was estimated by quantifying incidence and severity using a diagrammatic scale, based on the plant and the leaf immediately below the first ear. We found that incidence can efficiently replace severity at low epidemic levels, facilitating field diagnostics. Also, we observed genetic variability for traits related to polysora rust resistance. The landraces PARA 172, ARZM 05083 and the line L80 are recommended to integrate breeding populations for Puccinia polysora resistance as they may carry favorable alleles for disease control.

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.