Resumo -O objetivo deste trabalho foi identificar correlações canônicas entre caracteres morfológicos e componentes da produção de genótipos de trigo de duplo propósito, sob diferentes manejos de corte. Os experimentos foram realizados em 2013 e 2014, no delineamento de blocos ao acaso, em arranjo fatorial com cinco genótipos (BRS Tarumã, BRS Umbu, BRS Figueira, BRS Guatambu e BRS 277), quatro manejos de corte (sem corte, um corte, dois cortes e três cortes) e três repetições. Os grupos canônicos foram estabelecidos entre os caracteres morfológicos (grupo 1) e os componentes de produção (grupo 2). No grupo 1, foram avaliados número de perfilhos, diâmetro do colmo principal e dos perfilhos, e número de perfilhos férteis; no grupo 2, foram avaliados número de grãos por espiga e de espigas por metro quadrado, massa de grãos por espiga e de mil grãos, produtividade de grãos e peso hectolítrico. A correlação entre os grupos 1 e 2 depende do manejo de corte adotado. O diâmetro do colmo principal (nos manejos sem e com um corte), o diâmetro dos perfilhos (dois cortes), e o número total de perfilhos e de perfilhos férteis por planta (três cortes) devem ser priorizados para seleção de genótipos superiores quanto à produtividade de grãos e ao peso hectolítrico.Termos para indexação: Triticum aestivum, análise multivariada, manejo de corte, seleção indireta. Canonical correlations between morphological traits and yield components in dual-purpose wheatAbstract -The objective of this work was to identify canonical correlations between morphological traits and yield components in dual-purpose wheat, under different cutting managements. The experiments were carried out in 2013 and 2014, under a complete block design, in a factorial arrangement with five genotypes (BRS Tarumã, BRS Umbu, BRS Figueira, BRS Guatambu, and BRS 277), four cutting managements (no cuts, one cut, two cuts, and three cuts), and three replicates. The canonical groups were established between morphological traits (group 1) and yield components (group 2). In group 1, number of tillers, diameter of the main stem and of the tillers, and number of fertile tillers were evaluated; in group 2, the number of grains per spike and of spikes per square meter, the mass of grains per spike and of a thousand grains, grain yield, and hectoliter weight were evaluated. The correlation between groups 1 and 2 depends on the adopted cutting management. The diameter of the main stem (in the managements without and with one cut), tiller diameter (two cuts), and the total number of tillers and of fertile tillers per plant (three cuts) should be prioritized for selection of superior genotypes as to grain yield and hectoliter weight.

The main aim of this study was to investigate the phenotypic correlation of yield component traits using several environmental stratifications methods. We also aimed to propose cause and effect of relationships for grain yield components in soybean genotypes under several environmental conditions. The tests were conducted in the agricultural year of 2013/2014 in four growing sites in Rio Grande do Sul, Brazil. The experimental arrangement was randomized blocks in factorial scheme (11 x 4), consisting eleven soybean genotypes in four environments with four repetitions each. All the growing environments Tapera-RS, Derrubadas-RS and Frederico Westphalen-RS were classified as favorable for soybean cultivation. The traits such as total number of pods per plant, number of branches and number of pods with 2-3 grains showed significant linear correlations with grain yield in both methods of analysis. The path analysis was applied under favorable and unfavorable environments to accurately estimate the direct and indirect effect of traits on soybean grain yield. The mass of a thousand grains and plant height were highly associated with grain yield but mostly influenced by environmental effects. The total number of pods should be prioritized for selecting superior soybean genotypes due to its direct and indirect effects on grain yield. It has shown constant in all environmental conditions. The direct effects of number of branches and number of pods (with one grain) presented distinct effects on yield in favorable and unfavorable environments.

ABSTRACT. Methodologies using restricted maximum likelihood/ best linear unbiased prediction (REML/BLUP) in combination with sequential path analysis in maize are still limited in the literature. Therefore, the aims of this study were: i) to use REML/BLUPbased procedures in order to estimate variance components, genetic parameters, and genotypic values of simple maize hybrids, and ii) to fit stepwise regressions considering genotypic values to form a path diagram with multi-order predictors and minimum multicollinearity that explains the relationships of cause and effect among grain yieldrelated traits. Fifteen commercial simple maize hybrids were evaluated in multi-environment trials in a randomized complete block design with four replications. The environmental variance (78.80%) and genotypevs-environment variance (20.83%) accounted for more than 99% of the phenotypic variance of grain yield, which difficult the direct selection of breeders for this trait. The sequential path analysis model allowed the selection of traits with high explanatory power and minimum multicollinearity, resulting in models with elevated fit (R 2 > 0.9 and ε < 0.3). The number of kernels per ear (NKE) and thousand-kernel weight (TKW) are the traits with the largest direct effects on grain yield (r = 0.66 and 0.73, respectively). The high accuracy of selection (0.86 and 0.89) associated with the high heritability of the average (0.732 and 0.794) for NKE and TKW, respectively, indicated good reliability and prospects of success in the indirect selection of hybrids with highyield potential through these traits. The negative direct effect of NKE on TKW (r = -0.856), however, must be considered. The joint use of mixed models and sequential path analysis is effective in the evaluation of maize-breeding trials.

The objective was to identify phenotypic and genotypic associations, and cause-and-effect relations of secondary components on primary components to establish criteria in the indirect

There is a need to strengthen maize (Zea mays L.) breeding strategies based on multivariate selection to obtain high-yielding hybrids that are more stable and resilient to contrasting environmental conditions. Here, we show how the multi-trait stability index (MTSI) can be used to select maize hybrids for mean performance and stability of multiple traits. A set of 10 traits, including grain yield (GY), yield components, and plant-related traits with negative and positive desired selection gains (SGs), were accessed in 90 F 1 hybrids conducted in multi-environment trials. Hybrid and hybrid × location interaction effects were significant (p ≤ .001) for all analyzed traits. The MTSI provided positive gains for all the four traits that were wanted to increase (2.52% ≤ SG ≤ 4.86; mean, 3.28%), including GY (SG, 4.86%), and negative gains for all the six traits that were wanted to decrease (-20.28% ≤ SG ≤ -0.09%; mean, -6.70%), including tassel branch number (SG, -20.28%) and plant height (SG, -1.2%). We also observed desired gains for the stability of all traits. Direct and univariate selection for GY solely was not efficient to provide desired gains for all traits. The MTSI provides a unique, robust, and easy-to-handle selection process that allows identifying the strengths and weaknesses of hybrids. The index was found to be a powerful tool to develop better selection strategies, optimizing the use of resources and time, thus contributing to the sustainability of maize breeding programs worldwide.Abbreviations: DFL, distance from the flag leaf to the first branch of the tassel; DLN, distance for the last node to the first branch of the tassel; EH, ear height; GTB, genotype-by-trait biplot; GY, grain yield; KD, kernel depth; MET, multi-environment trial; MPE, mean performance and stability; MTSI, multi-trait stability index; NKE, number of kernels per ear; PH, plant height; SG, selection gains; TBN, tassel branch number; TKW, thousand-kernel weight; TL, tassel length; WAASB, weighted average of absolute scores from the singular value decomposition of the matrix of best linear unbiased predictions for the genotype × environment interaction effects generated by a linear mixed-effect model; WAASBY, superiority index that weights between mean performance and stability.

The aim of this study was to evaluate the phenotypic interrelation among agronomic characters associated with wheat grain yield of the main Brazilian cultivated genotypes through path analysis in two environments. The tests were conducted in Tenente Portela-RS and Braga-RS. The experimental design was randomized blocks arranged in factorial scheme, 2 locations × 17 genotypes and 3 repetitions. The evaluated characters were plant height, main stem spike mass, tiller spikes mass, main stem spike grains number, tiller spikes grains number, main stem spike grains mass, tiller spikes grains mass, mass of a thousand grains and grain yield. Path analysis was performed for characters associated with grain yield. The results show that main stem spike grains mass, main stem spike grains number, and tiller spikes grains mass have direct effects on grain yield. Larger main stem spike grains mass, main stem spike grains number, and tiller spikes grains mass should be considered for achieving genotypes of high grain yield potential.

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R E S U M ONo Planalto do Rio Grande do Sul, Brasil, local de clima subtropical, o cultivo da segunda safra de verão com a cultura da soja (safrinha), semeada após o cultivo de milho, vem agregando importância econômica, aumentando progressivamente sua área de cultivo e possibilitando maior produção de grãos durante o período de verão. Estudos dos caracteres dos genótipos semeados nessa condição específica, com efeito da redução da luminosidade, podem auxiliar nas futuras seleções em programas de melhoramento vegetal da cultura. O objetivo do trabalho foi avaliar as relações lineares entre caracteres de soja (Glycine max L.) e identificar caracteres para a seleção indireta, em segunda safra de cultivo de verão, em região subtropical. Dezoito cultivares de soja foram avaliadas em três locais do Rio Grande do Sul. As semeaduras foram realizadas em 09/01/2013, 10/01/2013 e 24/01/2013, para os experimentos conduzidos em Barra do Guarita, Vista Gaúcha e Tenente Portela, respectivamente. Foi utilizado o delineamento de blocos ao acaso, com quatro repetições. Foram mensurados os caracteres altura de inserção do primeiro legume, altura de planta, massa de cem grãos e produtividade de grãos. Realizou-se a análise de variância dos caracteres. Foi investigada a relação entre os caracteres por meio de análises de correlação e de trilha. No cultivo de soja em época de safrinha (segunda safra de verão), em clima subtropical, a altura de planta tem relação linear positiva com produtividade de grãos e pode ser usada para seleção indireta de cultivares mais produtivas. Palavras-chave: Glycine max L., relações lineares, seleção indireta. A B S T R A C TIn the highlands of Rio Grande do Sul, Brazil, with subtropical climate, the cultivation of the second summer crop with soybean (off-season), sowed after maize, has been adding economic importance, increasing progressively its cultivation area, and allowing greater grain yield during the summer period. Studies of traits of genotypes sown in this particular condition, with reducing luminosity effect, can assist in future selections in soybean plant breeding programs. The objective of this study was to evaluate the linear relations among soybean traits (Glycine max L.) and identify traits for indirect selection in the second crop of summer cultivation, in subtropical region. Eighteen soybean cultivars were evaluated in three locations of Rio Grande do Sul. Sowing was performed on Jan/09/2013, Jan/10/2013, and Jan/24/2013 for the experiments carried out in Barra do Guarita, Vista Gaúcha, and Tenente Portela, respectively. The randomized block design with four replications was utilized. The traits insertion of the first pod height, plant height, one hundred grains weight, and grain yield were measured. The traits analysis of variance was performed. Relation among traits was investigated through correlation and path analysis. In off-season soybean cultivation (second summer crop) in subtropical climate, plant height has positive linear relation with grain yield and it can be used for in...