Osvaldo Toshiyuki Hamawaki

Avaliação da qualidade fisiológica e sanitária de sementes de genótipos de soja do ciclo precoce/médio em Uberlândia, Minas Gerais

The objective of this work was to evaluate the percentage of variables in 18 lines of soybean (Glycine max) in terms of germination, seed vigour, health and productivity. The experimental design utilized consisted of randon blocks, with four replications, and 18 treatments, according to soybean genotypes. The genotypes UFV94-426803 e BR92-06665 showed the longest and shortest germination times, 96 and 69%, respectively. This variable showed a positive correlation with seed vigour (r= +0.79), and a negative correlation with the incidence of Fusarium semitectum, Phomopsis sojae e Colletotrichum dematium. (r= -0.33, -0.39, e ¾0.26, respectively). In terms of seed vigour, the lines CSP-5 e BR93-6957 represented the highest and lowest percentages, 90 and 54.5%, respectively. There was a positive correlation between seed vigour and grain productivity (r= +0.59) and a negative correlation between seed vigour and the incidence of F. semitectum and P. sojae (r= -0.36 e ¾0.60, respectively). The incidence of F. semitectum was 47% in the FT-2002 line and 9% in the CSP-5 line. The incidence of P. sojae in the genotypes BR93-6957 and UFV94-426803 was 49.7 and 2.1%, respectively. The CSP line presented the highest incidence of C. dematium (3.8%). The genotypes FT-2001 and UFV94-1896 showed the highest (3.9 t/ha) and the lowest (2.48 t/ha) grain productivity. There was a negative correlation between this variable and the incidence of P. sojae (r= -0.44). The cultivars BR-16 e OCEPAR-3 presented intermediated values for all variables, but did not show smaller yields (grain production) than the other genotypes available in this experiment.

Improvement in genetic characteristics and oil yield of selected soybean progenies from octuple crosses

Este estudo teve o objetivo de avaliar 44 cruzamentos octuplos de soja, em cadeia, nas geracoes F4:3[8] e F5:3[8], visando a selecao de progenies superiores quanto a produtividade de oleo e outros caracteres de importância agronomica. Os cruzamentos octuplos foram sintetizados cruzando-se parentais adaptados x exoticos em um sistema de cadeia durante tres geracoes, ate a obtencao de cruzamentos octuplos tendo 75% genes adaptados: 25% genes exoticos em um grupo, e hibridacoes de parentais adaptados x adaptados, em cadeia, originaram cruzamentos octuplos tendo 100% de genes adaptados, em outro grupo. No ano agricola 1994/95 foram avaliadas as progenies F4:3[8], sendo empregado o delineamento em blocos aumentados. As progenies F5:3[8] foram conduzidas, no ano agricola 1995/96, em tres experimentos delineados em blocos aumentados (sem repeticoes). As analises dos resultados revelaram que cruzamentos octuplos originaram progenies superiores para todos os caracteres estudados, inclusive em produtividade de oleo, obtendo-se valores de 707 kg/ha, no cruzamento C22. As estimativas de herdabilidade ao nivel de medias de parcelas, em termos medios, minimos e maximos, foram, respectivamente: tempo de maturidade (52,35%; 3,71%; 84,23%), valor agronomico (26,69%; 1,62%; 61,28%) e produtividade de graos (29,28%; 1,52%; 61,06%); os ganhos geneticos observados para produtividade de graos nas progenies F5:3[8] precoces, intemediarias e tardias foram, em geral, superiores aos respectivos ganhos geneticos esperados; e os ganhos geneticos observados para producao de oleo foram mais expressivos nas progenies F5:[8] precoces e tardias. A existencia de variabilidade genetica remanescente entre progenies selecionadas de alguns cruzamentos permite antever a possibilidade de se obterem ganhos adicionais em ciclos mais avancados de selecao para produtividade de graos e de oleo.

Phenotypic and genotypic correlations between soybean agronomic traits and path analysis

The goals of this research were to evaluate the phenotypic and genotypic correlations between agronomic traits, to perform path analysis, having as main character grain yield, and to identify indirect selection criteria for grain yield. The experiment was carried out in an experimental area located at Capim Branco farm, which belongs to Federal University of Uberlândia, during the growing season of 2015/2016.Twenty-four soybean genotypes were evaluated under randomized complete block design with three repetitions, of which agronomic traits and grain yield were measured. There was genetic variability for all traits at 5% probability level through the F-test. Thirty significant phenotypic correlations were also observed with values oscillating from 0.42 to 0.87, which indicated a high level of association between some evaluated traits. Additionally, we verified that phenotypic and genotypic correlations were essential of the same direction, being the genotypic ones of superior magnitudes. Plants with superior vegetative cycle had longer life cycles; this fact could be explained by the significant phenotypic correlations between the number of days to the blooming and number of days to maturity (0.76). Significantly positive phenotypic and genotypic correlations for the total number of pods per plant and grain yield per plant (0.84) were observed. Through the path analysis, the trait that contributed the most over grain yield was the number of pods with three seeds as it showed the highest direct effect on grain yield per plant, as well as a strong indirect effect on the total number of pods. Therefore, the phenotypic and genotypic correlations suggested high correlations between grain yield and number of branched nodes, the number of pods with two and three seeds, and the total number of pods. Also, the path analysis determined the number of pods with three seeds as having the highest favorable effect on grain yield, and thus, being useful for indirect selection toward productive soybean genotypes.

Genetic parameters and selection of soybean lines based on selection indexes

Defining selection criteria is important to obtain promising genotypes in a breeding program. The objective of this study was to estimate genetic parameters for agronomic traits and to perform soybean line selection using selection indices. The experiment was conducted at an experimental area located at Capim Branco farm, belonging to the Federal University of Uberlândia. A total of 37 soybean genotypes were evaluated in randomized complete block design with three replicates, in which twelve agronomic traits were evaluated. Analysis of variance, the Scott-Knott test at the 1 and 5% level of probability, and selection index analyses were performed. There was genetic variability for all agronomic traits, with medium to high levels of genotype determination coefficient. Twelve lines with a total cycle up to 110 days were observed and grouped with the cultivars MSOY 6101 and UFUS 7910. Three lines, UFUS FG 03, UFUS FG 20, and UFUS FG 31, were highlighted regarding grain yield with higher values than the national average of 3072 kg/ha. The direct selection enabled the highest trait individual gains. The Williams (1962) index and the Smith (1936) and Hazel (1943) index presented the highest selection gain for the grain yield character. The genotype-ideotype distance index and the index of the sum of ranks of Mulamba and Mock (1978) presented higher values of total selection gain. The lines UFUS FG 12, UFUS FG 14, UFUS FG 18, UFUS FG 25, and UFUS FG 31 were distinguished as superior genotypes by direct selection methods and selection indexes.

Correlations between traits in soybean (Glycine max L.) naturally infected with Asian rust (Phakopsora pachyrhizi)

Soybean (Glycine max L.)-breeding programs aim to develop cultivars with high grain yields and high tolerance to Asian soybean rust (Phakopsora pachyrhizi). Considering that the traits targeted for breeding are mainly quantitative in nature, knowledge of associations between traits allows the breeder to formulate indirect selection strategies. In this study, we investigated phenotypic, genotypic, and environmental correlations between the agronomic traits of soybean plants naturally infected with P. pachyrhizi, and identified agronomic traits that would be useful in indirectly selecting soybean genotypes for high yields. The study was conducted on the Capim Branco Farm, Uberlândia, Brazil, with 15 soybean genotypes, which were cultivated in a completely randomized block design with four replications. Fourteen phenotypic traits were evaluated using the GENES software. The phenotypic and genotypic correlations were positive and of a high magnitude between the total number of pods and the number of pods with two or three grains, indicating that the total number of pods is a useful trait for the indirect selection of soybean genotypes for high grain yields. Strong environmental correlations were found between plant height at blooming and maturity and grain yield and yield components.

Development of Brazilian Soybean Cultivars Well Adapted to Cerrado and Rust-Tolerant

The major diseases limiting soybean growth and yield must be either controlled or mitigated. Among these, soybean rust is the most harmful; in addition, Phakopsora pachyrhizi populations less susceptible to both IDM and IQe fungicides were observed. Therefore, this invention aimed at developing a new soybean cultivar rust resistant and highly productive. Generations were advanced by single seed descent method on the Capim Branco farm, Federal University of Uberlândia. Value for Cultivation and Use were carried out during a 3-year period (2010/13) in several locations, and Distinctness, Uniformity and Stability experiments for a 2-year period (2011/13) on the Capim Branco farm. Hence, we developed the novel soybean cultivar designated UFUS 7415. UFUS 7415 has shown high contents of oil (20%) and protein (40%), and high yield potential (4.300 kg ha-1) even in environments with Asian rust.

Soybean Breeding Aiming at increasing Productivity and Root-Knot Nematode Resistance

In Brazil, the root-knot nematode (Pratylenchus brachyurus) has gained importance, whatever because of the damage caused to soybean crops or because of its broad dispersion and incidences in producing areas. Therefore, this invention aimed at developing a new cultivar resistant to the major soybean diseases as well as to the root-knot nematode. As a result, we developed a soybean cultivar designated UFUS 8301. Generations were advanced by the single seed descent method. Value for Cultivation and Use assays were carried out during a 3-year period (2010/13). Distinctness, uniformity, and stability experiments were carried out during a 2-year period (2011/13). We used the reproduction factor (RF) statistics to assess damage and reproductive potentials of P. Brachyurus; analysis of variance tested differences between means. We accepted the null hypothesis there was no difference between UFUS 8301 and the parameter of resistance Crotalaria spectabilis. UFUS 8301 was found distinct from any other cultivar, homogeneous to the descriptors that had identified it and stable through generations. UFUS 8301 presented 19% oil and 39% protein on the seeds, and yield (3687.5 kg ha -1 ) above Brazilian national average.

Agronomic performance and genetic diversity among lines and soybean cultivars

Knowledge of genetic diversity is of great importance to the contribution of plant breeding, as it helps plant breeders to better selecting parents for establishment of segregating populations. This knowledge is especially important to crops that presents a narrow genetic base as soybean. The objective of this work was to assess agronomic performance and genetic diversity of lines and soybean cultivars, in order to find those ones with potential to be used as parents in breeding programs. Experiment was carried out during 2015/2016 season in the Federal University of Uberlândia farm known as Capim Branco. A randomized complete block designed was applied in order to assess twentythree morpho-agronomic features on twenty-four soybean genotypes. Significant genetic variability for all agronomic traits was found. Genotypes UFU B7, UFU B14, UFU B16, Msoy 6101 and UFUS 7910 were set as early maturity soybean, with life cycle duration ranging from 107.3 to 111 days. Genotypes UFU B1, UFU B3, UFU B8 and UFU B16 presented productivity values higher than national average of 2.870 kg ha. Genotypes were clustered by UPGMA, Tocher and canonical variables methods. Both UPGMA and Tocher methods formed four groups. NDF was the major contributor to genetic diversity. Hybridizations between UFU B3, UFU B8, UFU B16 genotypes with UFU B1 genotype might be promising for establishment of segregating populations shown superior genetic variability. Under these circumstances, it was concluded that agronomic features assessed were useful on detection of parents with potential to UFUs soybean breeding program.

Dissimilarity measures and hierarchical methods for the study of genetic diversity on soybean

In analysis of the genetic diversity on soybean can be used agronomic, morphological and molecular traits, which are subjected to multivariate biometrical analysis. There are different multivariate methodologies available such as Euclidean distance, Mahalanobis distance and different hierarchical methods. However, studies that may assist in the choice of such methods are lacking. The aim of this paper was to evaluate the clustering standards of soybean genotypes using Euclidean and Mahalanobis distances, following different hierarchical methods. The experiment was conducted in “Capim Branco” farm which belongs to the Federal University of Uberlândia and were used a complete randomized block design composed of 15 soybean genotypes (nine breeding lines and six cultivars) and four replications. The agronomic traits evaluated were: number of days to flowering and to maturity, height of the plant at flowering and at maturity, height of the insertion of the first pod, number of nodes on the main stalk in flowering and at maturity, number of grains per pod, total number of pods, severity of Asian rust, number of pustules and yield. The data were submitted to multivariate analysis in GENES program. The Mahalanobis distance or the Euclidean distance obtained by agronomic traits allows the determination of soybean genetic diversity. The use of the Euclidean distance in hierarchical methods allows a greater group differentiation. The UPGMA method and the nearest neighbor method shows a greater accuracy using the Mahalanobis distance and Euclidean distance.

Analysis of the genetic divergence of soybean lines through hierarchical and Tocher optimization methods

This study aimed to evaluate the clustering pattern consistency of soybean (Glycine max) lines, using seven different clustering methods. Our aim was to evaluate the best method for the identification of promising genotypes to obtain segregating populations. We used 51 generations F5 and F6 soybean lines originating from different hybridizations and backcrosses obtained from the soybean breeding program of Universidade Federal de Uberlândia in addition to three controls (Emgopa 302, BRSGO Luziânia, and MG/BR46 Conquista). We evaluated the following agronomic traits: number of days to flowering, number of days to maturity, height of the plant at maturity, insertion height of the first pod, grain yield, and weight of 100 seeds. The data was submitted to analyses of variance followed by average Euclidean distance matrix estimation used as measure of dissimilarity. Subsequently, clusters were formed using the Tocher method and dendrograms were constructed using the hierarchical methods simple connection (nearest neighbor), complete connection (most distant neighbor), Ward, median, average within cluster connection. The nearest neighbor method presented the largest number of genotypes in group I and showed the greatest similarity with the Tocher optimization method. The joint use of these two methodologies allows for differentiation of the most genetically distant genotypes that may constitute the optimal parents in a breeding program.