Abstract Human consumption of vegetable soybeans is increasing, and consequently, breeding programs need to be encouraged and optimized. Therefore, there is a need to understand the relationship between the traits evaluated in the R6 (full seed) and R8 (full maturity) stages and estimate genetic divergence. At two sites and two crop seasons, we evaluated 42 progenies (F6 generation) from crosses between vegetable soybean genotypes and three commercial cultivars. In general, we found significant coincident correlations between environments. Positive and significant correlations between pod width (PWR6) and hundred-seed weight (HSW) and between PWR6 and hundred-pod weight (HPW) suggest the possibility of replacing the labor-intensive process of obtaining HSW and HPW by estimating PWR6, which is faster and easier to apply. The unweighted pair-group method arithmetic average analysis allocated soybean genotypes into six major clusters. Furthermore, information from the present work may guide practical actions in breeding programs.

ABSTRACT Due to the high impact of Asian soybean rust (SBR) in Brazilian croplands, several studies have been conducted in order to maintain or increase the grain yield gain over years in the presence of the pathogen. The aim of this study was to define a breeding strategy applying uni and multivariate approaches for diallel analyzes in early generation trials and contrasting disease conditions. Thus, assessing genetic parameters to identify traits related to greater tolerance to soybean rust. Deploying a North Carolina design II scheme (4 elite commercial cultivars × 10 rust-tolerant experimental lines), we obtained 40 F2 crosses that were evaluated in a randomized complete block design with 4 replicates. The crosses were conducted in two environments, contrasting only for the fungicide management (with and without rust control), enabling the estimation of the rust impact on 11 traits, divided into two groups: adaptive and reproductive. A multi-environment diallel model was applied assuming all effects as fixed in order to estimate the general (GCA) and the specific (SCA) combining abilities. The multivariate diallel analysis was performed in each rust management using MANOVA to test the genetic effects. The rust conditions were the most important source of variation for almost all evaluated traits. Using the contrasting disease conditions, we were able to identify crosses with desirable SCA and parents with GCA, which implies that tolerance can be used as a strategy to deal with SBR. The implementation and the use of multivariate diallel analysis aiming to increase the efficiency of genotype selection for rust tolerance is discussed.

Abstract The white mold, caused by Sclerotinia sclerotiorum (Lib.) de Bary, is one of the most important diseases of soybean. The objective of the present work was to evaluate the soybean reaction to the fungus S. sclerotiorum, which causes white mold, in a partial diallel with 50 crosses. The Group I of parents was composed of ten experimental lines with high grain yield and the group II consisted in five genotypes with possible resistance to white mold. Ten plants of each cross in the F4 generation and the parents were evaluated for reaction to fungus infection using the method of inoculation in detached leaves in order to assess the severity of the disease and to later estimate the combining abilities. Estimates of the specific combining ability (SCA) was a significant reaction to S. sclerotiorum, indicating that there is variability for fungus resistance due to non-additive genes action.

Abstract The present study aimed to evaluate the combining ability of 16 soybean genotypes using a partial diallel. Two experiments were carried out to estimate the general (GCA) and specific (SCA) combining ability, one with 64 crosses and the other with 16 parents. At the R8 stage, F2 plants and the parents were evaluated for the following traits: number of days to flowering (NDF), number of days to maturity (NDM), plant height at maturity (PHM), and grain yield (GY). Results indicated genetic variability between the parents and between the crosses. For GY, six (37.5%) parents stood out with high yield. The GCA and SCA estimates were significant for all traits, revealing additive and non-additive effects. The parent USP 04-17.027 (4) was superior for presenting the highest means, heritability, and GCA. The cross (4x13 = USP 04-17.027 x USP 231-2224-12) stood out owing to the highest SCA for GY.

RESUMO: A ferrugem asiática da soja é a doença que mais tem preocupado os produtores e pesquisadores desde sua primeira evidência. Ela é causada pelo fungo biotrófico Phakopsora pachyrhizi Sydow & P. Sydow que encontrou condições extremamente favoráveis para a sua disseminação no Brasil. O sintoma mais característico apresenta-se nas folhas, inicialmente na face adaxial, como pequenos pontos angulares com menos de um milímetro de diâmetro, juntamente com os uredósporos (esporos) de coloração acinzentada. O manejo se dá por meio de um conjunto de práticas que garanta a boa convivência entre a planta e o patógeno e sem que ocorra danos significativos à lavoura. O trabalho objetivou avaliar a tolerância à ferrugem asiática estimando as perdas causadas pela infestação natural a campo. Os experimentos com a geração F4 (2014/15) foram delineados em blocos ao acaso com quatro repetições. Foram realizadas categorias de experimentos, envolvendo dois tipos de genótipos (cruzamentos e genitores) e dois tipos de manejos de doenças com fungicidas. Para a análise dos dados foi aplicado um teste, para duas amostras dependentes, a fim de verificar a significância da estimativa do efeito ferrugem. Considerando a produtividade e a tolerância, os cruzamentos mais importantes foram 104 (USP 14-01-20 x EMGOPA 313) e 149 (USP 93-05.552 x EMGOPA 313). Os cruzamentos 147 (USP 93-05.552 x PI 153.282) e 137 (USP 70.108 x PI 153.282) foram tolerantes tanto na avaliação de redução da produtividade e do tamanho de semente. Houveram evidências de tolerância à ferrugem asiática nos cruzamentos e nos genitores. O teste estatístico revelou a significância das estimativas de efeito ferrugem em soja.

ABSTRACT: Asian soybean rust is an important disease that has deeply troubled farmers and researchers since it was first reported. The causal agent, biotrophic fungus Phakopsora pachyrhizi Sydow & P. Sydow, has found extremely favorable conditions for its dissemination in Brazil. The most characteristic symptom of infection appears in the leaves, initially on the adaxial leaf surface, as small angular points less than 1mm in diameter, together with gray-colored uredospores (spores). Management involves a set of practices that guarantee coexistence between the plant and the pathogen without significant damage to the crop. The objective of this research was to evaluate tolerance to Asian rust by estimating losses caused by natural infection in the field. Experiments with generation F4 (2014/15) plants were established in a randomized blocks design with four replicates, with two types of genotypes (crosses and parents) and two schemes for disease management using fungicides. For analysis of the data, a test was applied on two dependent samples to verify the significance of the estimate of the rust effect. With regard to grain yield and tolerance, the most outstanding crosses were 104 (USP14-01-20 × EMGOPA313) and 149 (USP93-05.552 × EMGOPA313). Crosses 147 (USP93-05552 × PI153.282) and 137 (USP70.108 × PI153.282) were graded as tolerant in the evaluation of both yield reduction and seed size. We found evidence of tolerance to Asian rust in both crosses and parents. The statistical test revealed the significance of the rust effect estimates in soybean.

Peanut (Arachis hypogaea) is the fifth most produced oil crop worldwide. Besides lack of water, fungal diseases are the most limiting factors for the crop. Several species of Arachis are resistant to certain pests and diseases. This study aimed to successfully cross the A-genome with B-K-A genome wild species previously selected for fungal disease resistance, but that are still untested. We also aimed to polyplodize the amphihaploid chromosomes; cross the synthetic amphidiploids and A. hypogaea to introgress disease resistance genes into the cultivated peanut; and analyze pollen viability and morphological descriptors for all progenies and their parents. We selected 12 A-genome accessions as male parents and three B-genome species, one K-genome species, and one A-genome species as female parents. Of the 26 distinct cross combinations, 13 different interspecific AB-genome and three AA-genome hybrids were obtained. These sterile hybrids were polyploidized and five combinations produced tetraploid flowers. Next, 16 combinations were crossed between A. hypogaea and the synthetic amphidiploids, resulting in 11 different hybrid combinations. Our results confirm that it is possible to introgress resistance genes from wild species into the peanut using artificial hybridization, and that more species than previously reported can be used, thus enhancing the genetic variability in peanut genetic improvement programs.

The objective of this work was to use a partial diallel to evaluate the combining ability of 14 soybean genotypes and recommend superior combinations. Seven of the genotypes had high oil yield; other seven exhibited tolerance to sudden death syndrome and they generated 49 hybrids in a diallel cross without reciprocals. F2plants of each cross and the parents were evaluated for the following traits: number of days to maturity (NDM), oil content in the seeds (OC), grain yield (GY) and oil yield (OY). The results indicated the existence of genetic variability in the parents and progeny for all the traits. The rank of the parents based on the means was similar to the rank based on general combining ability (GCA) for all the traits. The specific combining ability (SCA) and the GCA were significant for all the traits, with a predominance of additive effects. The parent with the highest GCA and mean for OC was the cultivar A 7002; on the other hand, the lowest values were found in PI 520733 and IAC 100. The crosses with the highest oil yields were those involving parent A 7002, except when it was crossed with IAC 100.

O objetivo deste trabalho foi quantificar os efeitos da interação genótipo x ambiente (GxE) sobre a produtividade de grãos em progênies de soja pré-selecionadas para resistência à ferrugem asiática (Phakopsora pachyrhizi). Doze ensaios de avaliação de progênies (linhagens F6 e F7) foram conduzidos em diferentes ambientes (combinação de locais, anos e tratamentos fungicidas para controle de doenças de final de ciclo, incluindo ou não a ferrugem). A análise "additive main effects and multiplicative interaction" (AMMI) capturou, como padrão da interação GxE, 57% da variação associada aos resíduos de não aditividade, dos quais 44% foram retidos no primeiro componente principal de interação e o restante, no segundo. O primeiro componente associou-se a diferenças entre os anos de avaliação, o que denota imprevisibilidade na predição. O segundo componente, no entanto, associou-se ao manejo diferenciado do cultivo, no que se refere ao controle ou não das doenças. Entre os genótipos de ampla adaptabilidade produtiva, as linhagens USP 02-16.045 e USP 10-10 apresentaram desempenho destacado.

The objective of this work was to quantify the effects of genotype x environment (GxE) interaction on grain yield in soybean progenies pre-selected for resistance to Asian soybean rust (Phakopsora pachyrhizi). Twelve trials evaluating progenies (lines F6 and F7) were carried out in different environments (combination of locations, years, and fungicide treatments to control late season diseases, including or not rust). Additive main effects and multiplicative interaction (AMMI) analysis captured, as GxE interaction pattern, 57% of the variance associated with the residues of non-additivity, of which 44% were retained in the first principal component of interaction, and the remainder in the second. The first component was associated with the differences between the years of evaluation, which denotes unpredictability. The second component, however, was associated with different crop managements, related to the control or not of the diseases. Among genotypes with wide yield adaptability, the USP 02-16.045 and USP 10-10 lineages stood out.

Genetic diversity is essential for crop breeding and one way to estimate it is through the concept of genetic base, which can be defined as the number of ancestors and their relative genetic contributions (RGC) to each cultivar. The RGC can be estimated through the coefficient of parentage between the ancestors and cultivars. Previous studies determined that the genetic base of Brazilian soybean was very narrow. The objective of this work was to evaluate the pedigree of 444 Brazilian soybean cultivars to estimate their genetic base. The cultivars were divided according to their release dates and according to their origin (public or private), and the genetic base for each group was also estimated. We found 60 ancestors, of which the top four (CNS, S-100, Roanoke and Tokyo, respectively) contribute 55.3% of the genetic base. Only 14 ancestors have an RGC over 1.0%, and they represent 92.4% of the genetic base. Analysis of the release dates indicated that there has been an increase in the number of ancestors over time, but the four main ancestors were the same over all periods, and their cumulative RGC increased from 46.6% to 57.6%, indicating a narrowing of the genetic base.

Soybean is one of the most valuable and profitable oil crop species and a thorough knowledge of the genetic structure of this crop is necessary for developing the best breeding strategies. In this study, a representative collection of soybean cultivars recommended for farming in all Brazilian regions was genotyped using 27 simple sequence repeat (SSR) loci. A total of 130 alleles were detected, with an average allelic number of 4.81 per locus. These alleles determined the core set that best represented this soybean germplasm. The Bayesian analysis revealed the presence of two clusters or subgroups within the whole collection (435 soybean cultivars) and the core set (31 entries). Cultivars of similar origin (ancestral) were clustered into the same groups in both analyses. The genetic diversity parameters, based on the SSR loci, revealed high similarity between the whole collection and core set. Differences between the two clusters detected in the core set were attributed more to the frequency of their ancestors than to their genetic base. In terms of ancestry, divergent groups were presented and a panel is shown which may foster efficient breeding programs and aid soybean breeders in planning reliable crossings in the development of new varieties.

O objetivo deste trabalho foi caracterizar linhagens de soja quanto à reação à ferrugem asiática. No ano agrícola 2004/2005 conduziu-se três experimentos com genótipos de ciclo médio e três com tardios, delineados em blocos casualizados, com quatro repetições. Utilizou-se 12 linhagens e duas cultivares, para cada ciclo. Em cada experimento, com plantas de mesmo ciclo, o manejo fitossanitário diferiu como segue: três aplicações de carbendazim ou três de flutriafol ou sem fungicida. As linhagens com elevado rendimento, com notas baixas para os sintomas e resistentes ao acamamento, foram selecionadas e novamente testadas em 2005/2006. Genótipos com elevada severidade e rendimento foram considerados tolerantes, os com baixa severidade e elevado rendimento, como moderadamente resistentes. Entre os genótipos com ciclo médio, observou-se resistência moderada em uma linhagem e tolerância em cinco. Entre os de ciclo tardio, as seis linhagens apresentaram resistência moderada. A linhagem USP 97-08135 apresenta maior tolerância à ferrugem.

Our objective was to characterize soybean experimental lines for Asian soybean rust reaction. In the 2004/2005 growing season, three experiments were conducted with middle-cycle and three with late-cycle genotypes, designed in randomized blocks with four replications. Twelve experimental lines and two cultivars of each cycle were used. In each experiment the plant management differs as follows: three applications of carbendazim or three of flutriafol or without applications. The experimental lines with high yield, low notes to the symptoms and resistance to lodging, were selected and tested again in the 2005/2006 growing season. Genotypes with high severity and yield were considered tolerant to rust and the low severity and high yield ones as moderately resistant. Among the medium-cycle genotypes, there was moderate resistance to rust in one line and tolerance in five. Among the late-cycle genotypes, the six lines showed moderate resistance. The line USP 97-08135 is more tolerant to rust.

Locos microssatélites e dados de genealogia foram utilizados para avaliar a diversidade genética de um grupo de 168 cultivares brasileiras de soja. Os dezoito locos utilizados apresentaram em média 5,06 alelos por loco e coeficiente de diversidade genética médio de 0,58. O dendrograma final resultante da matriz de distância genética de Roger modificado por Wright, apresentou boa concordância com a ancestralidade dos grupos formados. Também foi estimado os coeficientes de parentesco entre as cultivares, sendo observada variação de 0 a 1 com média de 0,18, enquanto que as similaridades para os locos microssatélites (1- GD) variou de 0,01 a 0,90 com média de 0,25. A correlação entre as duas matrizes obtidas determinada pelo teste Z de Mantel apresentou valor baixo, 0,31, mas significativo (p<0,001). Os resultados obtidos sugerem que os locos microssatélites aliados às informações de genealogia proporcionam melhor análise da diversidade genética de cultivares de soja.

In this study, simple sequence repeats (SSR) loci and pedigree data were used to investigate the genetic relationship in a group of 168 Brazilian soybean cultivars. Eighteen SSR loci produced an average of 5.06 alleles and a mean gene diversity of 0.58 for the cultivars studied. Genetic distance (GD) was determined using the modified Roger's Wright distance, and a final dendrogram was in agreement with the cultivar pedigree. A distance matrix based on the coefficient of parentage scores was also generated for the cultivars, which ranged from 0 to 1, with a mean of 0.18, whereas SSR-based genetic similarity (1- GD) ranged from 0.01 to 0.90, with a mean of 0.25. Mantel's Z test showed that the similarity matrices generated from both the data sets were low, but significantly correlated (r = 0.31, p<0.001). The results showed that SSR data and pedigree analyses could help to quantify more accurately the degree of relationship among the soybean cultivars.

O amendoim (Arachis hypogaea) possui genoma AB e é uma das mais importantes culturas oleaginosas em todo o mundo. Os principais problemas da cultura no Brasil são as doenças fúngicas. Várias espécies do gênero Arachis são resistentes a pragas e doenças. Este trabalho visou a identificar espécies silvestres pertencentes à seção Arachis associadas aos genomas A ou B (ou " não-A" ) do amendoim que são resistentes à mancha castanha (Cercospora arachidicola), mancha preta (Cercosporidium personatum) e ferrugem (Puccinia arachidis). Para a identificação de genótipos resistentes a doenças fúngicas, bioensaios utilizando folhas destacadas foram realizados em condições de laboratório, com inoculação artificial, temperatura controlada de 25ºC e fotoperíodo de 10h luz/14h escuro, por 20-42 dias, de acordo com a espécie fúngica. A maioria dos acessos das espécies silvestres foram mais resistentes que os acessos de A. hypogaea para uma, duas ou todas as espécies fúngicas estudadas. Arachis monticola, considerada como o possível ancestral tetraplóide ou como um derivativo de A. hypogaea, também mostrou-se mais suscetível a Cercosporidium personatum e Puccinia arachidis, quando comparado à maioria das espécies silvestres. Portanto, acessos de germoplasma silvestre com genoma A ou B estão disponíveis para serem utilizados na introgressão de genes de resistência a doenças fúngicas no amendoim.

Groundnut (Arachis hypogaea) has an AB genome and is one of the most important oil crops in the world. The main constraints of crop management in Brazil are fungal diseases. Several species of the genus Arachis are resistant to pests and diseases. The objective of our experiments was to identify wild species belonging to the taxonomic section Arachis with either A or B (or " non-A" ) genomes that are resistant to early leaf spot (Cercospora arachidicola), late leaf spot (Cercosporidium personatum) and rust (Puccinia arachidis). For the identification of genotypes resistant to fungal diseases, bioassays with detached leaves were done in laboratory conditions, with artificial inoculation, a controlled temperature of 25ºC and a photoperiod of 10 h light/14 h dark, for 20-42 days, depending on the fungi species. Most of the accessions of wild species were more resistant than accessions of A. hypogaea for one, two or all three fungi species studied. Arachis monticola, considered to be a possible tetraploid ancestor or a derivative of A. hypogaea, was also more susceptible to Cercosporidium personatum and Puccinia arachidis, as compared to most of the wild species. Therefore, wild germplasm accessions of both genome types are available to be used for the introgression of resistance genes against three fungal diseases of peanut.

Esta pesquisa visou avaliar linhagens experimentais de soja, com a finalidade de identificar genótipos que reúnam características de alta produtividade e tolerância a insetos. O material foi composto por três populações obtidas de um dialelo parcial 4 x 4 envolvendo quatro genitores tolerantes a insetos e quatro cultivares de elevada produtividade. Foram conduzidos 24 experimentos no delineamento aleatório, em blocos com duas repetições subdivididas em conjuntos experimentais com testemunhas comuns, combinando as três populações e oito ambientes. Com base na produtividade de grãos, concluiu-se que: existe variabilidade genética remanescente entre as linhagens nas três populações; o manejo diferenciado com controle intensivo de insetos e controle ecológico de insetos (CII vs. CEI) é um representante eficiente de ambientes diversos; o local Anhembi destacou-se como de alta produtividade em todas as situações; para a capacidade de gerar linhagens superiores, sobressaíram-se os genitores IAC-100, D72-9601-1, BR-6, Davis e IAS-5; destaques especiais envolveram os cruzamentos do genitor IAC-100 com IAS-5, Davis, OCEPAR-4 e BR-6.

This research aimed to evaluate experimental soybean lines, with the finality to identify genotypes that contine traits of elevate yield and insect tolerance. Plant material included three populations derived from a 4×4 partial diallel having four parents insect resistants and four with elevated yield cultivars. The 24 experiments were carried out in randomized complete block design with two replications subdivided in three sets with common checks, testing the three populations in eight environments. There is genetic variability among lines in the three populations; the management systems were efficient as representative of the environmental diversity; the Anhembi location exhibited with high seed yield in all situations; as for the ability in originating superior lines, the following parents stand out: IAC-100, D72-9601-1, BR-6, Davis, and IAS-5; the best outstanding biparental crosses occurred when the IAC-100 parent was crossed with IAS-5, Davis, OCEPAR-4, and BR-6.

O objetivo deste trabalho foi determinar o grau de correlação entre parâmetros que avaliam a adaptabilidade e a estabilidade da produtividade de óleo em soja. Os parâmetros foram estimados a partir da análise de dados resultantes da avaliação de 93 linhagens de soja, divididas em três ciclos de maturação (28 precoces, 38 semiprecoces e 27 intermediárias). Os ensaios foram conduzidos em doze ambientes do município de Piracicaba, SP, Brasil. Os seguintes parâmetros foram correlacionados: média geral (m i), coeficiente de regressão (b i), ecovalência de Wricke (ômegaWi), ecovalência AMMI (ômegaAi), variância dos desvios da regressão (sigma2di) e coeficiente de determinação (R²i). Utilizou-se a correlação (r) de Sperman do ordenamento das linhagens, segundo cada parâmetro. As correlações entre m i e b i e entre os parâmetros de estabilidade entre si (ômegaWi, ômegaAi, sigma2di e R²i) foram positivas e significativas (0,53 < r < 0,93) . As correlações entre os parâmetros de adaptabilidade e estabilidade foram baixas ou negativas e não significativas (-0,39 < r < 0,38), exceto entre b i e R²i (r = 0,49 e 0,89 para as linhagens precoces e intermediárias, respectivamente). Os parâmetros de estabilidade classificam a ordem das linhagens de forma similar e, provavelmente, pertencem ao mesmo conceito de estabilidade. Os resultados indicam que é difícil a seleção simultânea para adaptabilidade e estabilidade da produtividade de óleo em soja.

The objective of this work was to determine the degree of correlation among parameters that evaluate oil yield adaptability and stability in soybean. The parameters were estimated starting from data analysis resultants of the evaluation of 93 soybean lines divided in three maturation cycles (28 early, 38 semiearly and 27 intermediate). The trials were carried out in twelve environments of the municipal district of Piracicaba, São Paulo, Brazil. The following parameters were correlated: grand mean (m i), regression coefficient (b i), Wricke ecovalence (omegadi), AMMI ecovalence (omegaAi), regression deviations variance (sigma2di) and determination coefficient (R²i). The parameters were compared using the ranking Sperman correlation of the lines, according to each parameter. The correlations among m i and b i and among the parameters of stability to each other (omegadi,omegaAi, sigma2di and R²i) were positive and significant (0.53<r<0,93). The correlations between the adaptability and stability parameters were low or negatives and not significant (-0.39<r<0.38), except among b i and R²i (r = 0.49 and 0.89, for the early and intermediate lines, respectively). The stability parameters present rank orders of the lines in a similar way and, probably, they belong to the same stabillity concept. The results indicated that is difficult the simultaneous selection for oil yield adaptability and stability in soybean.