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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.

Background Two endemic lycophyte species Isoetes cangae and Isoetes serracarajensis have been recently described in the State of Pará in the Amazon forest located in northern Brazil. Isoetes L. has survived through three mass extinctions. Plants are considered small-sized, heterosporous, and can display a great diversity of physiological adaptations to different environments. Thus, the current study aimed to estimate the genetic variation of the populations of I. cangae and I. serracarajensis to generate information about their different mechanisms for survival at the same geographical location that could point to different reproductive, adaptative and dispersal strategies and should be considered for effective conservation strategies. Methods The genetic diversity and population structure of I. cangae and I. serracarajensis were investigated using Inter Simple Sequence Repeat (ISSR) molecular markers. Total genomic DNA was isolated, and the genetic diversity parameters were calculated. Results The sixteen primers produced 115 reproducible bands, 87% of which were polymorphic. A high level of polymorphic loci (81.74% and 68.48%) and a high Shannon index (Sh = 0.376 and 0.289) were observed for I. cangae and I. serracarajensis, respectively. The coefficient of genetic differentiation between population areas (GST) showed a higher value in I. serracarajensis (0.5440). Gene flow was higher in I. cangae (1.715) and lower in I. serracarajensis populations (0.419). Overall, the results further show that I. serracarajensis and I. cangae are two species with considerable genetic variation and that these differences may reflect their habitats and modes of reproduction. These results should be considered in the development of effective conservation strategies for both species.

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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 present work aimed to estimate the adaptability and stability of new papaya hybrids. The experiments were carried out at the company Caliman Agrícola S/A, in the municipalities of Linhares-ES and Pureza-RN, with seven hybrids from inbred parents of the groups 'Solo' and 'Formosa' and three controls ('Golden', 'Calimosa', and 'Tainung 01'). The experiment consisted of a randomized block design with four replications and ten plants per plot. The variables mean fruit weight (MFW), number of commercial fruits (NCF), and production (PROD) were measured at 270, 360, 450, and 540 days after planting. Afterward, the adaptability and stability of the hybrids were estimated using the Lin and Binns, Eberhart and Russell, and Mixed Models. MFW was less affected by the evaluation periods and showed high behavior predictability. The hybrids UC10, UC12, UC14, UC15, and UC16 were the most adapted and predictable and can be recommended for the regions where the experiment took place.

Developing superior lines based on a simultaneous response from many traits of agronomic importance is a fundamental strategy to expand papaya cultivar supply, mainly the much-needed cultivars belonging to group Formosa. Our goal was to associate the pedigree method with REML/Blup procedure to select plants of progenies F 2:3 with superior agronomic performance. The variance components and genetic parameters were estimated using REML approach, and the genetic values were predicted using Blup methodology. The combined selection was performed using the IG2 selection index based on weights associated with agronomic values to indicate the best progenies and lines. The heritability estimates of progeny mean were high in most traits and evidenced significant genetic variability between progenies. The narrow-sense individual heritability was moderate in traits such as commercial fruits and soluble solid contents, which indicates a PLANT BREEDING -Article favorable condition for selections within progenies. The index was consistent in the selection of six superior progenies according to the assessed traits. This index also enabled promising genetic gains in traits of great interest such as yield and pulp thickness.Although the progenies are derived from self generations, they proved to be superior in traits of significant importance such as yield, commercial fruits, and pulp thickness when compared to the Tainung-01 hybrid, which is a worldwide-planted cultivar used as a reference to Formosa representatives. Six lines were selected within the superior progenies to continue the Formosa group-lines development program. The association of the pedigree method with REML/Blup procedure can be useful to assist breeders in an autogamous breeding program.

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.