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Correlation and path analysis for yield components of supersweet cornIn breeding programs, information on the correlation between characters is essential to improve the simultaneous selection of characters. However, the measurement and interpretation of the magnitude of a correlation can lead to mistakes in the selection strategy. The objective of this study was to evaluate, using path analysis, the direct and indirect components between primary production and yield of supersweet corn ear and identify the characteristics that most contribute to ear yield (basic variable). The variables used explained 94.77% of the variance in ear weight (R 2 ). The path analysis showed that only two characters, grain volume (0.2637) and ear volume (0.2536), had a direct effect on production. It appears, therefore, that although the majority of the characters present high correlation estimates, these Em programas de melhoramento genético, informações sobre a correlação entre caracteres são de grande importân-cia para se aperfeiçoar a seleção simultânea de caracteres. Contudo, a quantificação e a interpretação da magnitude de uma correlação podem resultar em equívocos na estratégia de seleção. O objetivo deste trabalho foi avaliar, por meio da análise de trilha, as relações, direta e indireta, entre os componentes primários de produção e a produtividade de espiga de milho superdoce, e identificar os caracteres que mais contribuem para a produtividade de espiga (variável básica). Verifica-se que as variáveis utilizadas explicaram 94,77% da variação do peso de espiga (R 2 ). Pela análise de trilha, apenas dois caracteres, o volume do grão (0, 2637) e o volume de espiga (0, 2536), apresentaram efeito direto na produção. Constata-se, portanto, que, apesar de a maioria dos caracteres apresentarem altas estimativas de correlação, essas ocorreram por efeitos indiretos de outros caracteres. Assim, tanto para seleção direta, quanto para seleção indireta, essas características são eficientes no aumento do peso médio da espiga de milho superdoce. Neste caso, a melhor estratégia seria a seleção simultânea de caracteres, enfatizando-se as características cujos efeitos indiretos são maiores. É oportuno salientar que o volume de grão e volume de espiga apresentaram maiores herdabilidades, quando comparados com peso de espigas, ou seja, 91,92, 88,6 e 80,52%, respectivamente. A alta herdabilidade estimada (91,92 e 88,6%) é um indicativo de possibilidades de elevados ganhos genéticos na seleção.Palavras-chave: coeficiente de trilha, efeitos diretos e indiretos, resposta correlacionada.

The aim of the current study is to estimate the correlation coefficients and the consequence of genotypic correlations on direct and indirect effects through path analysis between agronomic traits of maize hybrids used for silage production. Eight (8) topcross hybrids and seven (7) checks were analyzed in completely randomized blocks, with six replications, in two environments: Campos do Goytacazes and Itaocara counties-Rio de Janeiro State, in the crop year 2015/2016. The following agronomic traits were assessed: plant height, first ear height, culm diameter, number of ears, ear yield with straw at silage maturity, ear yield without straw at silage maturity, grain yield at silage maturity, grains ratio in the fresh matter and fresh matter yield.

This study aimed to compare estimates of genetic gains using four indices of selection, based on the least squares method and the additive index through the multi-trait REML/BLUP (Best linear unbiased prediction/restricted maximum likelihood) to perform a selection early in S 1 families. Eighty S 1 testcross hybrids were proportionally separated into two groups: the CIMMYT-SH (CSH) and CIMMYT-8HS (C8HS) populations and assessed for main trait required by the market. The selection indices Smith & Hazel, Williams, Pesek & Baker, Mulamba & Mock and the additive multi-trait REML/BLUP were tested. The estimated gains from selection were assessed for each group (CSH and C8HS) separately, so as to maintain the identity of each population. Among the four selection indices based on the ANOVA (analysis of variance), the Mulamba & Mock was the most suitable for the selection of half-sib families in super sweet corn. The additive multi-trait REML/BLUP index showed even better predicted genetic gains than Mulamba & Mock, and was efficient to select half-sib families in super sweet corn. Based on the REML/BLUP were selected from each population, the 20 most promising progenies to continue the super sweet corn breeding program. The high level of coincidence between the multi-trait REML/BLUP and Mulamba & Mock indices indicates similar efficiency for selection purposes. However, REML/BLUP method showed better genetics gains, may be recommend the use of for future selection activities.

The sweet corn market has been expanding in recent years and the trend is to maintain this growth, targeting mainly the export market. The goal was to evaluate the agronomic performance per se and hybrid backcrosses of four sweet corn populations and to estimate genetic parameters inherent in these populations, in order to achieve promising lines to obtain hybrids. The following genotypes were used for a test: the donor population sh gene, two recurring populations interpopulation hybrids of common maize, four sweet corn populations, and four sweet corn interpopulation hybrids. The traits evaluated were: plant height, stand, number of ears, prolificacy, number of grain rows, as well as average ear diameter, average diameter cobs, average husked ear length, average unhusked ear length, average unhusked ear weight, average husked ear weight, ear relationship, unhusked ear yield and husked ear yield.  The backcross method was efficient for obtaining sweet corn populations with good agronomic performance. Because the sweet corn interpopulation hybrid presents agronomic performance similar toP8 x C8 interpopulation hybrid, it can be inferred that all sweet corn populations backcrossed are recommended for use in obtaining lines, in order to obtain productive hybrids, or even directly as hybrid trade after further assessments.