RESUMO: Objetivou-se mensurar o efeito da associação entre caracteres agronômicos relacionados à produtividade de grãos de canola cultivada em diferentes épocas de semeadura, através da análise de trilha. Assim como também objetivou-se obter um método para predizer o teor de óleo nos grãos, ajustando um modelo multivariado através da análise por espectroscopia na região do infravermelho próximo. O experimento foi conduzido em campo, utilizando-se o delineamento de blocos ao acaso, em parcelas subdivididas no tempo, sendo quatro parcelas (épocas de semeadura) e seis subparcelas (híbridos de canola), com quatro repetições. Em cada híbrido foram realizadas observações fenológicas e determinada a produtividade de grãos. Os dados foram submetidos à análise de variância em ambiente R pelo teste F, a cinco de probabilidade. O teor de óleo nos grãos foi determinado pelo método químico tradicional, e com base na assinatura espectral no infravermelho próximo de amostras dos grãos foi estabelecida regressão dos mínimos quadrados parciais (PLS-R) para estimar o teor de óleo nos grãos de canola. As épocas de semeadura influenciaram os componentes de produção e o teor de óleo dos grãos de todos híbridos. Os caracteres número de grãos em cinco plantas (0,6857) e altura (0,4943) apresentaram maiores estimativas de correlação positiva com a produtividade de grãos, assim como os maiores valores de efeito direto positivo sobre a produtividade, 0,2494 e 0,1595 respectivamente. Entretanto, o ciclo total (-0,7848), juntamente com dias em florescimento (-0,4520) apresentou correlação significativa negativa com a produtividade. A técnica NIR associada à PLS-R foi capaz de predizer o teor de óleo nos grãos, resultando em bons modelos preditivos (R2 de 0,86 e RMSE de 1,56 na validação externa) que podem ser usados com sucesso na análise da qualidade das amostras após colheita e nos programas de melhoramento genético.

ABSTRACT: This study measured the effect of the association between agronomic traits related to the yield of canola grains grown at different sowing dates through path analysis. Another objective was to obtain a method to predict the oil content in the grains, fitting a multivariate model through near-infrared (NIR) spectroscopy analysis. The experiment was conducted in the field using a randomized block design in plots subdivided by time, with four plots (sowing dates), six subplots (canola hybrids), and four replicates. In each hybrid, phenological observations were performed, and the grain yield was determined. The data were subjected to analysis of variance in the R environment using the F test at 5% probability. The oil content in the grains was determined by the traditional chemical method, and based on the NIR spectral signature of the grain samples, partial least squares regression (PLS-R) was established to estimate the oil content in the canola grains. The sowing dates influenced the production components and oil content of the grains of all hybrids. The trait number of grains in five plants (0.6857) and their height (0.4943) had greater estimates of positive correlations with grain yield, as well as higher values of positive direct effects on yield (0.2494 and 0.1595, respectively). The NIR technique combined with PLS-R was able to predict the oil content in the grains, resulting in good predictive models (R2 of 0.86 and root mean square error (RMSE) of 1.56 in external validation).

Resumo O objetivo deste trabalho foi estimar parâmetros genéticos e fenotípicos associados à precocidade, e selecionar progênies de soja (Glycine max) que associem alta produtividade de grãos e precocidade. Progênies F3:4 e F3:5 foram avaliadas durante os anos agrícolas de 2016/2017 e 2017/2018, em cinco ambientes. Dados de dias para o florescimento, dias para maturação plena e produtividade de grãos foram coletados e analisados via abordagem de modelos mistos. Foram estimados parâmetros genéticos e fenotípicos, ganhos esperados e realizados com a seleção, e respostas correlacionadas. Os componentes variância genética e interação genótipos por ambientes foram significativos. A herdabilidade oscilou de 50,14%, para produtividade, a 90.37%, para maturação plena. O ganho realizado para maturação plena variou de −0.17 a −2.57%. Observou-se correlação positiva entre os três caracteres avaliados. A seleção de 5,0% das progênies mais precoces reduziria a média produtiva em cerca de 5,02%, mas também reduziria o tempo até maturação plena de 125 para 119 dias, em detrimento de 210,5 kg ha−1 do potencial produtivo. Cinco progênies apresentaram maturação plena até 120 dias. A progênie 51 superou o parental mais produtivo (NK 7074 RR), com rendimento de grãos de 4.975 kg ha−1 e 128 dias até maturação plena.

Abstract The objective of this work was to estimate genotypic and phenotypic parameters associated with early maturity, and to select soybean (Glycine max) progenies that are high yielding and early maturing. F3:4 and F3:5 progenies were evaluated during the 2016/2017 and 2017/2018 crop years in five environments. Data on days to full maturity, days to flowering, and grain yield were collected and analyzed using the mixed model approach. Genotypic and phenotypic parameters, expected and achieved selection gains, and correlated responses were estimated. The components genetic variation and genotype x environment interaction were significant. Heritability fluctuated from 50.14%, for grain yield, to 90.37%, for full maturity. The achieved genetic gain for full maturity ranged from −0.17 to −2.57%. A positive correlation was observed among the three evaluated traits. The selection of 5.0% of the earliest-maturing soybean progenies would reduce mean grain yield by about 5.02%, but also reduce time to reach full maturity from 125 to 119 days, in detriment of 210.5 kg ha−1 potential yield. Five progenies reached full maturity up to 120 days. Progeny 51 overperformed the more productive parent (NK 7074 RR), with a grain yield of 4,975 kg ha−1 and 128 days to full maturity.

Resumo: O tamanho das sementes de soja é um fator que ainda necessita de estudos, pois a relação tamanho das sementes, qualidade fisiológica, estabelecimento e produtividade no campo apresenta controvérsias. Objetivou-se avaliar os efeitos do tamanho das sementes no estabelecimento da cultura da soja e na qualidade fisiológica das sementes. Em campo utilizou-se fatorial 2 x 3 x 3, sendo, duas cultivares (M 5947 IPRO e 59HO124 IPRO), três tamanhos de sementes (5.5, 6.0 e 6.5 mm) e três estandes de plantas (280.000, 320.000 e 360.000 plantas.ha-1). Foram avaliados características agronômicas e produtividade de grãos. Após a colheita, as sementes das parcelas com população de 320.000 plantas foram classificadas por tamanho utilizando-se peneiras com crivos circulares, 5.5 mm, 6.0 mm, 6.5 mm e 7.0 mm de diâmetro. Para a avaliação da qualidade fisiológica, considerou-se esquema fatorial 2 x 4, sendo, 2 cultivares e 4 tamanhos de sementes. Avaliou-se germinação, emergência em canteiro, envelhecimento acelerado, matéria seca de plântulas e índice de velocidade de emergência. Sementes menores dão origem a plantas mais baixas e com menor altura de inserção do primeiro legume. Sementes maiores apresentam maior qualidade fisiológica. A cultivar M 5947 IPRO apresentou melhores desempenho e qualidade de sementes.

Abstract: The size of soybean seeds needs further study because its relationships with physiological quality, field establishment, and yield are controversial. The aim of this study was to evaluate the effects of seed size on soybean establishment and seed physiological quality. In the field, a 2x3x3 factorial design was used, with two cultivars (M 5947 IPRO and 59HO124 IPRO), three seed sizes (5.5, 6.0, and 6.5 mm), and three sowing densities (280,000, 320,000, and 360,000 plants.ha-1). Agronomic traits and grain yield were evaluated. After harvest, only seeds from plots with a population of 320,000 plants were classified by size using circular sieves with 5.5-mm, 6.0-mm, 6.5-mm, and 7.0-mm mesh sizes. For the evaluation of physiological quality, a 2x4 factorial design was applied, with two cultivars and four seed sizes. Germination, seedling emergence, accelerated aging, seedling dry matter, and emergence speed index were evaluated. Smaller seeds gave rise to shorter plants with a lower first pod insertion height. Larger seeds had higher physiological quality. The M 5947 IPRO cultivar showed better seed performance and quality.

Resumo: Genótipos mais produtivos da cultura da soja é um dos principais objetivos dos programas de melhoramento. Existem poucos estudos quanto à seleção de caracteres associados à qualidade e desempenho de sementes de soja. Objetivou-se predizer parâmetros fisiológicos e genéticos sobre a qualidade de sementes produzidas em populações segregantes de soja, provenientes de genitores com diferentes grupos de maturidade. Foram avaliados oito genótipos da população segregante F2: 3 de soja (163, 24, 57, 108, 164, 169, 157 e 81), cultivados na safra 2018/19. Para a condução do experimento foi utilizado o delineamento inteiramente casualizado. Avaliou-se a qualidade fisiológica das sementes por meio dos testes de germinação, tetrazólio e análise de imagem. As análises estatísticas foram realizadas utilizando-se uma abordagem de modelos mistos. Foi possível observar maior vigor nas sementes dos lotes 108, 164 e 169, cujos resultados estiveram entre os melhores na maioria dos parâmetros analisados. Maior incidência de dano mecânico e por percevejos pode ser usado para explicar o menor vigor, como observado nos genótipos 57 e 163, enquanto o dano por umidade não corroborou com os testes de vigor das sementes. A resposta dos genótipos às análises realizadas indicou maior influência de características genéticas destes do que efeito do grupo de maturidade relativa. Não foi possível observar evidente efeito do grupo de maturidade relativa e o vigor das sementes de soja.

Abstract: Productive soybean genotypes is one of the main objectives of soybean breeding programs. However, there are few studies on the selection of characteristics associated with the quality and performance of soybean seeds. The objective in this study was to predict physiological and genetic parameters associated with seed quality in segregating soybean populations derived from parents of differing maturity groups. Eight genotypes of the F2:3 segregating soybean population (numbered 163, 24, 57, 108, 164, 169, 157, and 81) cultivated in the 2018/19 harvest were evaluated. To conduct the experiment, a completely randomized design was used. The physiological quality of the seeds was evaluated by germination test, tetrazolium test, and image analysis. Statistical analyses were performed by using a mixed model approach. Greater seed vigor was observed in the genotypes 108, 164, and 169, whose results were among the best for most of the analyzed parameters. The greater mechanical damage and damage due to stink bugs can explain the lower vigor of some seeds, as observed in genotypes 57 and 163, while weathering damage did not correspond to the results of the seed vigor tests. The analyses indicated a greater influence of genetic characteristics than of relative maturity group on the responses of the genotypes. No effect of relative maturity group on soybean seed vigor was evident.

Abstract This study estimated the general and specific combining abilities and mean heterosis of tobacco lines of the varietal groups Flue-Cured Virginia (FCV) and Air-Cured Burley (BY). In addition, possible advantages and an improved strategy of using hybrids in tobacco breeding in the tropics were discussed. Ten BY and 13 FCV lines were crossed in a diallel mating design. The hybrids and parental lines were evaluated at two locations in Southern Brazil. The mean heterosis was 5.37% for FCV and zero for BY lines, although higher than 15% in some combinations. The occurrence of heterosis indicates dominance in the control of tobacco yield. Tobacco breeding programs must focus primarily on improving the performance of lines per se and then on the identification of the best hybrid by testing combinations.

Abstract This study aimed to compare recombinant inbred lines (RIL) obtained via the bulk method with doubled haploid lines (DHL). For comparison, 190 DHL and 194 RIL were evaluated simultaneously at two different locations. Phenotypic and genetic parameters were estimated for the traits green leaf yield (GLY) and alkaloid content (ALK). The results of the RIL and DHL evaluations were similar for ALK. Conversely, estimates of genetic variation and heritability in the DHL were higher than those in the RIL for GLY. However, the mean estimate of the RIL was 13.3% higher than that of the DHL and thus, the annual gain with selection was higher for the RIL. The use of DHL in a recurrent selection program will be efficient in comparison to RIL if a large number of lines are obtained, which must undergo a preliminary selection before the most intensive evaluation to identify the lines to be recombined.

RESUMO Várias características devem ser consideradas simultaneamente na seleção de cultivares de tabaco para atender às necessidades dos agricultores, fabricantes e consumidores. Nesse contexto os melhoristas devem conhecer as correlações entre as características de importância econômica, a fim de adotar a melhor estratégia de seleção para elas. A utilização de índices de seleção tem se mostrado uma das estratégias mais eficientes para selecionar caracteres correlacionados. No caso do tabaco, nenhum relato foi encontrado na literatura para a seleção de múltiplas características. Neste estudo, demonstramos a eficiência da Soma do Índice de Variáveis Padronizadas (SSV) para a seleção de múltiplas características em tabaco. O método foi avaliado usando uma coleção de treze linhagens parentais e seus híbridos oriundos de um esquema dialélico. Os híbridos, as linhagens parentais e as testemunhas foram avaliados em dois locais. As características avaliadas foram produtividade (YLD), índice geral de qualidade (IGQ), relação talo/lâmina, porcentagem total de alcalóides e porcentagem total de açúcares. Consideramos os pesos para o indíce de acordo com a importância econômica de cada característica: 0,4 para YLD, 0,3 para GQI e 0,1 para os demais caracteres. O índice SSV mostrou-se eficiente e fácil de interpretar, podendo ser utilizado para se ter ganho genético para quase todos os caracteres na direção desejada. A capacidade geral de combinação (CGC) explicou a maior parte da variação do índice na análise dialélica. A estimativa de heterose média foi de 2,02%. Algumas combinações de híbridos exibiram níveis de heterose maiores que 10%, indicando que uma maior atenção pode precisar ser dada à comercialização de híbridos F1.

ABSTRACT Several traits must be simultaneously considered in selection of tobacco cultivars for meeting the requirements of farmers, manufacturers and consumers. Breeders should have an understanding of associations between economically-important traits in order to devise the best strategy to have response to selection for all them. Utilization of selection indices has been shown to be one of the most efficient strategy for selecting for correlated characters. In tobacco, no reports can be found within the academic literature for multiple trait selection. In this study we demonstrate the efficiency of the Sum of the Standardized Variables Index (SSV) for multi-trait selection in tobacco. The method was evaluated using a collection of thirteen inbred lines and hybrids derived using a diallel scheme. The hybrids, parental lines, and checks were evaluated in two field locations. The traits assessed were yield (YLD), general quality index (GQI), leaf stem to lamina ratio, percent total alkaloids, and percent total sugars. We considered weights according to the economic importance of each trait: 0.4 for YLD, 0.3 for GQI and 0.1 for the remaining characters. The SSV index proved to be efficient and easy to interpret, and could be used to generate genetic gain for almost all characters in the desired direction. General combining ability (GCA) explained the larger part of the variation of the index in the diallel analysis. The mean heterosis estimate was 2.02%. Some hybrid combinations exhibited heterosis levels greater than 10%, indicating that increased attention might need to be given to commercialization of F1 hybrids.

Abstract The aim of this study was to estimate genetic and phenotypic parameters associated with progenies from the recurrent selection program for grain yield in soybean. The evaluation of S0:1 progenies was in Lavras in the 2015/2016 crop year. The S0:2 progenies were evaluated in Lavras, Nazareno, and Itutinga. The S0:3 progenies were evaluated in Lavras, Ijaci, and Itutinga in the following crop years. The following traits were evaluated: days to flowering, days to full maturity, bottom pod height, plant height, lodging, and grain yield. The expected gain and gain achieved from selection, genetic correlation, and correlated response were estimated. The variance components show variability among the progenies. It was possible to obtain gains from selection for grain yield for all selection intensities (1, 5, 10, 15, 20, 25, and 30%). The variability and the high performance of the progenies indicate that implementation of the recurrent selection program can be successful.

RESUMO O herbicida lactofen vem sendo utilizado por produtores nas mais diversas condições, visando aumentar a produtividade da soja. Objetivou-se estudar a influência de lactofen e do fito-hormônio cinetina nos caracteres morfoagronômicos, partição de carboidratos e produtividade, em cultivares de soja. Foram conduzidos três experimentos em campo, além de um experimento em casa-de-vegetação. Utilizou-se delineamento em blocos casualizados, com quatro repetições. Os tratamentos foram: lactofen [144 g ha-1 de ingrediente ativo (i.a.)], lactofen + cinetina (144 g ha-1 de i.a. + 0,5 g ha-1), cinetina (0,5 g ha-1), corte manual das gemas apicais e controle. Na subparcela, foram utilizadas seis cultivares de soja (M 6410 IPRO, M 5917 IPRO, NS 7670 RR, NS 6909 IPRO, BMX Lança IPRO e Produza IPRO). Em campo, foram avaliados o índice de acamamento, altura de plantas, número de nós e ramos, vagens e grãos por planta, massa de 100 grãos e produtividade. Em casa-de-vegetação, foram quantificados o amido, açúcares redutores, sacarose e açúcares totais nas folhas, caules e raízes de três cultivares de soja. A aplicação de lactofen em V6 influenciou nas características morfoagronômicas das cultivares no campo e incrementou a produtividade em 312 kg ha-1 de soja, considerando-se todas as cultivares. O fito-hormônio não influenciou nas características morfoagronômicas e produtividade. Os tratamentos não induziram alteração na partição de carboidratos destinados às raízes.

ABSTRACT The herbicide lactofen has been used by producers in many conditions, in order to increase the soybean yield. This study aimed to evaluate the influence of lactofen and the phytohormone kinetin on the morpho-agronomic traits, carbohydrate partitioning and yield, in soybean cultivars. Three experiments were carried out in the field, in addition to one experiment in a greenhouse. A randomized block design, with four replications, was used. The treatments were: lactofen [144 g ha-1 of active ingredient (a.i.)], lactofen + kinetin (144 g ha-1 of a.i. + 0.5 g ha-1), kinetin (0.5 g ha-1), manual cutting of apical buds and control. In the subplots, six soybean cultivars (M 6410 IPRO, M 5917 IPRO, NS 7670 RR, NS 6909 IPRO, BMX Lança IPRO and Produza IPRO) were used. In the field, the plant lodging index, plant height, number of nodes and branches, pods and grains per plant, mass of 100 grains and grain yield were evaluated. In the greenhouse, the starch, reducing sugars, sucrose and total sugars in the leaves, stems and roots of three soybean cultivars were quantified. The application of lactofen in the V6 stage influenced the morpho-agronomic traits of the cultivars in the field and increased the soybean yield by 312 kg ha-1, considering all the cultivars. The phytohormone did not influence the morpho-agronomic traits neither the grain yield. The treatments did not induce modification in the partitioning of carbohydrates destined to the roots.

Abstract To compare agronomic performance and phenotypic stability among individual soybean lines and a multiline, eight cultivars and a mixture of them were evaluated in six environments in the 2014/2015 and 2015/2016 crop seasons. At maturity, grain yield (bg ha-1), lodging score, plant height (cm), and first pod height (cm) were evaluated. In the 2015/2016 season, the grain oil and protein content were also evaluated. The GxE interaction was determined by the ecovalence method. The cultivar V-TOP RR had the highest yield, but it was also the highest contributor to the GxE interaction, while the multiline was one of the most stable. The average yield of the multiline did not differ from the average yield of the lines, i.e., the multiline was stable and high yielding. For the other traits, there were no differences between the averages of lines and the multiline by the confidence interval. The mixture of lines is an efficient strategy to increase phenotypic stability in soybean.

Abstract Although cultivars of autogamous plants are homogeneous genotypes, they may show natural variability due to mechanical mixing, natural hybridization, and mutation. The aim of the present study was to estimate genetic and phenotypic parameters and to identify and select superior genotypes that associate good performance in traits of interest from a heterogeneous population derived from the cultivar BRS Favorita RR. The evaluation experiments were carried out in two crop years and five cities of the state of Minas Gerais, Brazil, in a lattice design, using progenies and the control ‘BRS Favorita RR’. Plant height, first pod height, days to full maturity, lodging score, and grain yield were evaluated. For estimation of the variance components, analysis of deviance was performed by the restricted maximum likelihood (REML) method. The results show that there is difference among treatments and that it is possible to select progenies that outperform the control for all traits evaluated.

Abstract In breeding of sweet sorghum hybrids, non-additive genetic effects are important in phenotypic expression of the traits of interest. The aim of this study was to evaluate the general combining ability (GCA) of sweet sorghum lines and the specific combining ability (SCA) of the hybrids for agronomic and technological traits. Five fertility restorer lines, four male-sterile lines, and their hybrids from partial diallel crosses were evaluated in experiments laid out in a 5 x 6 triple rectangular lattice design in the municipalities of Lavras, MG and Sete Lagoas, MG, Brazil. Diallel analysis was performed using the Griffing model adapted to partial diallel crosses. There was a significant effect of GCA and SCA for most of the traits evaluated, indicating the participation of additive or dominant genes in inheritance. The restorer lines CMSX508, BRS 511, CMSXS643, and CMSXS646 show potential for use as parents in sorghum breeding programs.

O objetivo desta pesquisa foi verificar o efeito da biofortificação de cultivares de soja tipo-alimentação pela aplicação de doses de zinco via foliar. O experimento foi instalado em delineamento inteiramente casualizado com quatro repetições, em esquema fatorial 5 × 5, consistindo em cinco cultivares de soja: BRS 010 (tegumento preto), BRS 213 (amarelo), BRSMG 790A (amarelo), BRSMG 800A (marrom) e Favorita RR® (amarelo) combinado com cinco doses de zinco aplicadas no estádio reprodutivo 4 (0, 0,91, 1,82, 2,73 e 6,37 mg L-1). Os parâmetros analisados foram a altura da planta, altura da inserção do primeiro legume, número de legumes por planta, número de grãos por planta, massa de legumes por planta, massa de grãos por planta, massa de cem grãos, composição mineral, lipídios e proteínas dos grãos. A adubação foliar com doses de zinco aumentou a altura da planta, a massa e o teor de proteína nos grãos de soja. O uso de doses de zinco via foliar proporcionam aumento significativo do teor de zinco no grão independente da cultivar estudada, apresentando respostas crescentes no conteúdo de zinco em função da dose de zinco aplicada.

The objective of this research was to verify the effect of biofortifying food-type soybean grains with different foliar applied zinc rates. The experiment was completely randomized with four replicates, in a 5 × 5 factorial scheme, which consisted of five soybean varieties: BRS 010 (black tegument), BRS 213 (yellow), BRSMG 790A (yellow), BRSMG 800A (brown), and Favorita RR® (yellow) combined with five zinc foliar rates applied at the reproductive 4 (R4) stage (0, 0.91, 1.82, 2.73, and 6.37 mg L-1). The analyzed parameters were plant height, first pod insertion height, number of pods per plant, number of grains per plant, pod weight per plant, grains mass per plant, 100-grain dry matter, mineral composition of the grains, lipid and protein content. Foliar fertilization with zinc increased plant height, grain mass, and protein content in soybean grains. It also significantly increased zinc content in the grain and this increase was independent of the studied variety, but was a function of the zinc rate applied.

Resumo: O objetivo deste trabalho foi avaliar o potencial per se de linhagens macho-estéreis e restauradoras de sorgo-sacarino (Sorghum bicolor), bem como detalhar a heterose manifestada quanto a algumas características relacionadas direta ou indiretamente à produção de etanol, à taxa de acúmulo e à previsibilidade. As avaliações foram realizadas com 20 genótipos, dos quais 4 linhagens restauradoras de fertilidade (R), 3 linhagens macho-estéreis (A) e 12 híbridos experimentais (H) resultantes do cruzamento dialelo parcial entre as linhagens A e R, além de um híbrido comercial CV198 como testemunha, em quatro épocas de colheita. Os experimentos foram realizados nos municípios de Lavras e Sete Lagoas, no Estado de Minas Gerais. As características mensuradas foram altura de planta, produção de massa verde, extração de caldo, conteúdo de sólidos solúveis totais e megagramas de Brix por hectare. As linhagens macho-estéreis A1 e as restauradoras R1 e R2 apresentam melhor potencial per se, ao se considerar todos os caracteres e a sua taxa de acúmulo e a previsibilidade de comportamento, nas diferentes épocas de colheitas. A heterose é significativa para todos os caracteres. Os híbridos H11, H13, H14, H21, H22 e H33 são promissores por seu maior desempenho per se e maior heterose.

Abstract: The objective of this work was to evaluate the potential per se of male-sterile and fertility-restorer lines of sweet sorghum (Sorghum bicolor), as well as to detail the heterosis manifested for some traits directly or indirectly related to ethanol production, accumulation rate, and predictability. Evaluations were performed for 20 genotypes, of which 4 are fertility-restorer lines (R), 3 are male-sterile lines (A), and 12 are experimental hybrids (H) resulting from the partial diallel cross between lines A and R, besides a commercial hybrid CV198 used as a check, in four harvest seasons. The experiments were carried out in the municipalities of Lavras and Sete Lagoas, in the state of Minas Gerais, Brazil. The measured traits were plant height, green mass production, juice extraction, total soluble solids content, and megagrams of Brix per hectare. The male-sterile A1 and the fertility-restorer R1 and R3 lines show the best potential per se, considering all traits and their accumulation rate and predictability over harvest times. Heterosis is significant for all traits. The H11, H13, H14, H21, H22, and H33 hybrids are promising because of their better performance per se and higher heterosis.

Abstract Genetic diversity is an essential factor for the success of any plant breeding program and should be considered to ensure genetic gain through breeding. In Brazil, research on the genetic diversity and population structure of soybean is required since the species is an important commodity of the country. The study addressed the genetic diversity and population structure of 77 soybean genotypes using 35 SSR markers. The estimate of the diversity index showed that the level of genetic diversity in the soybean collection is low. Similarly, the Jaccard coefficient and Bayesian model based on clustering analysis confirmed the low diversity among soybean genotypes, providing evidence for the assumption of a genetic bottleneck effect on Brazilian soybean genotypes. The results also reinforced the importance of finding and incorporating new genetic resources of soybean in the genetic pool of Brazilian soybean to warrant genetic gain in soybean breeding in the future.