Abstract The aim was to study the genetic control of the agronomic efficiency at low N availability in maize. Experiments were conducted in seven environments in a square lattice design with 49 hybrids, consisting of 48 crosses and one commercial hybrid, evaluated with and without application of N in top dressing. Grain yields with (GYHN) and without (GYLN) application of nitrogen in top dressing were assessed, and these traits were used to calculate the agronomic efficiency at low N availability (AELN) and the harmonic mean of the relative performance (HMRP). According to the joint analysis of variance of the diallel crosses and the estimates of the general and specific combining abilities, these traits were highly significant. Note that in general AELN was controlled by non-additive genetic effects and the hybrids H7, H3, H47 and H10 and the lines IG3-2, IG3-1, IG4-5, IG4-1 and IG4-6 show higher grain yield without top dressing.

ABSTRACT Maize is importance in the semiarid region due to its forage potential. However, the large number of hybrids on the market hampers the selection of the hybrid by the producer. Given the above, the objective of this paper is to identify genotypes with productive potential for forage and grain production according to the characteristics of the semiarid region of Brazil. Twenty genotypes with different genotypic classes were evaluated in two years (2018 and 2019) in the municipality of Gracho Cardoso, state of Sergipe. The experiments were carried out in a randomized complete block design (RCBD), with two replicates. Genotype characteristics, grain yield, and forage mass were evaluated and the results were estimated using mixed models and GT Biplots. The genotypic classes consisting of topcrosses and intervarietal hybrids showed high average grain yield and the three classes produced equally on average for forage mass. It was observed that the HI, HTC, and V genotypic classes were the most responsive for grain yield, forage mass, and dry matter content, respectively. Therefore, it is concluded that the genetically broad-based hybrids (HTC and HI) were the most promising for the semiarid of region of Sergipe, while interspecific hybrids were the most productive and stable.

RESUMO O milho é bastante cultivado na região semiárida brasileira e contém alto valor energético na dieta animal. Sabendo disto, objetivou-se caracterizar diferentes classes genéticas de milho quanto ao seu potencial forrageiro nas condições semiáridas de Sergipe. Para isso, foram avaliados 36 genótipos em blocos incompletos em Látice quadrado reticulado 6x6, com duas repetições, na fazenda experimental da Embrapa – Semiárido, em Graccho Cardoso-SE. As variáveis analisadas foram: altura da planta, diâmetro do colmo, peso de planta, massa fresca, massa seca, porcentagem de massa seca e massa de forragem. Com os dados obtidos foi realizada análise de variância com auxílio do software SAS 9,4 e, para a geração dos componentes principais (CP) e gráficos, foi utilizado o software R com o pacote “GGEBiplotGUI”. Todas as variáveis apresentaram diferenças significativas entre classes genéticas. Os dois primeiros componentes principais contemplaram 83,9% da variação total. O autovalor do primeiro CP (CP1) foi de 4,11, considerado muito significativo, já que a soma de todos os autovalores foi de 6,99. A porcentagem de massa seca, diâmetro do colmo, peso de planta, massa fresca, seca e de forragem obtiveram maior capacidade de discriminar as classes genotípicas. Os híbridos intervarietais ficaram mais próximos do genótipo “ideal”. A maior correlação positiva foi entre massa de forragem e massa seca. Os híbridos simples e triplos destacaram-se individualmente na altura da planta e porcentagem de massa. A massa seca e de forragem obtiveram maiores médias em todas as classes, exceto nos híbridos simples. As variedades foram as menos estáveis nas avaliações. Os híbridos intervarietais apresentaram maior potencial forrageiro e os duplos, topcross e variedades maior variabilidade genética, as demais classes não são indicadas para agricultores de baixa e média tecnologia quando cultivados em região semiárida para forragem de milho.

ABSTRACT Corn is widely grown in the semi-arid region and contains high energy value in the animal diet. Thus, the aim of this study was to characterize different genetic classes of maize cultivated for forage potential in the semiarid conditions the Sergipe. For this, 36 genotypes were evaluated in incomplete blocks in lattice square reticulate 6x6, with two replications, in the experimental farm of Embrapa - Semiárido, in Graccho Cardoso-SE. The variables analyzed were: plant height, stem diameter, plant weight, fresh weight, dry weight, percentage of dry weight and forage weight. With the data obtained was accomplished an analysis of variance with the help of software SAS 9,4 and, for generation the principal component analysis (PCA) and graphics, was used the software R with the package “GGEBiplotGUI”. All the variables showed significant differences between genetic classes. The first two main components included 83.9% of the total variation. The eigenvalues of the first PC (PC1) were 4,11, considering more significant, since the sum of all was of 6,99. The percentage of dry mass, stem diameter, plant weight, fresh, dry and forage mass obtained greater hability to discriminate genotypic classes. The intervarietal hybrids were closer to the “ideal” genotype. The greatest positive correlation was between forage weight and dry weight. The single and triple hybrids stood out individually in plant height and percentage of mass. The dry and forage mass obtained higher averages in all classes, except for simple hybrids. The varieties were the least stable in the evaluations. The intervarietal hybrids showed greater forage potential and the double, topcross and varieties had greater genetic variability, already to the genetic classes they are not indicated for farmers of low and mean tech in the semiarid region for forage of maize.

Abstract The current methodologies used to evaluate environmental similarities do not allow the simultaneous analysis and categorization of the environments. The objective of this study was to verify the possibility of using the Bayesian network (BN) to detect similarities between environments for plant height, lodging, and grain yield in maize. Thirteen experimental varieties were grown in six environments to measure the traits plant height, lodging, and grain yield. The BN was constructed for each trait, using the Hill-Climbing algorithm. Results were compared with the simple part of the genotypes x environments interaction, clustering by the Lin’s method and by simple correlation between environments. The Lin’s method clustered environments with predominance of complex interaction for all traits. The BN is efficient to analyze environmental similarity for plant height and grain yield since it detected the highest correlations. The BN revealed no connections among the environments that presented predominance of complex interaction.

ABSTRACT. The Brazilian popcorn has low genetic variability and the successful development of advanced lines, new popcorn cultivars with high grain yield (GY) and expansion volume (PE) is dependent on parental selection and precise determination of heterotic groups. The aim of this study was to evaluate genetic variability and identify heterotic groups in synthetic populations of popcorn, using diallel crosses. Thus, nine synthetic populations were crossed using complete diallel scheme. The GY and PE traits of 36 hybrids and reciprocals were evaluated in a randomized complete block design with 72 treatments and two replicates in two years. The effects of non-additive genes were the most important in the genetic control of these traits, indicating a favorable situation to produce hybrids. The reciprocal effect is mainly due to non-maternal effects for GY and PE. The highest GY values were obtained for the 02 x 08, 04 x 09, 05 x 09, and 01 x 09 crosses and the highest PE were obtained for the 07 x 01 and 03 x 04 crosses. The exploitation of synthetic populations from S3 lines can be an alternative to increase the genetic variability for grain yield and popping expansion in popcorn breeding programs.

Abstract Breeding new maize varieties that take up more N from the soil and increase N fixation is a crucial source of combined nitrogen in agricultural systems. Thus, this study aimed to select superior maize parental lines efficient in the use of nitrogen and Azospirillum brasilense. Three experiments were conducted in two agricultural seasons aiming to allocate all diallel hybrids in three different nitrogen conditions. The experiments were performed in a RCB design with two replications, and the diallel was analyzed using the mixed model approach. The general combining ability and Azospirillum use efficiency were applied to select the best parental line. The most promising hybrid combinations were “I-08 x II-06”, “I-02 x II-04”, and “I-01 x II-02”. Parents involved were selected for the development of hybrids. Parents I-01, I-02, I-08, II-01, II-02, II-04, II-05, and II-06 were selected to explore the basic population in the A. brasilense-use efficiency breeding program.

Resumo: O objetivo deste trabalho foi comparar a abordagem bayesiana e os métodos frequentistas para estimar as médias e os parâmetros genéticos em experimentos multiambientes de soja. Cinquenta e uma linhagens de soja e quatro testemunhas foram avaliadas em delineamento de blocos ao acaso, em seis ambientes, com três repetições, e a produtividade de grãos foi determinada. As distribuições “half-normal” a priori e uniformes foram utilizadas em combinação com parâmetros obtidos de dados de 18 genótipos coletados em experimentos anteriores e relacionados. Os valores genotípicos de genótipos com alta e baixa produção de grãos, agrupados pela abordagem bayesiana, diferiram das médias obtidas pela inferência frequentista. A soja avaliada pela abordagem bayesiana apresentou valores de parâmetros genéticos de modelos mistos (REML/Blup) próximos daqueles das seguintes variáveis: herdabilidade média (h2mg), acurácia da seleção dos genótipos (Acgen), coeficiente de variação genético (CVgi%) e coeficiente de variação ambiental (CVe%). Portanto, em experimentos multiambientes, a metodologia de modelos mistos e a abordagem bayesiana produzem resultados similares de parâmetros genéticos.

Abstract: The objective of this work was to compare the Bayesian approach and the frequentist methods to estimate means and genetic parameters in soybean multienvironment trials. Fifty-one soybean lines and four controls were evaluated in a randomized complete block design, in six environments, with three replicates, and soybean grain yield was determined. The half-normal prior and uniform distributions were used in combination with parameters obtained from data of 18 genotypes collected in previous and related experiments. The genotypic values of the genotypes of high- and low-grain yield, clustered by the Bayesian approach, differed from the means obtained by the frequentist inference. Soybean assessed through the Bayesian approach showed genetic parameter values of the mixed model (REML/Blup) close to those of the following variables: mean heritability (h2mg), accuracy of genotype selection (Acgen), coefficient of genetic variation (CVgi%), and coefficient of environmental variation (CVe%). Therefore, the mixed model methodology and the Bayesian approach lead to similar results for genetic parameters in multienvironment trials.

RESUMO: O feijão-vagem (Phaseolus vulgaris L.) é uma hortaliça rica em nutrientes, muito apreciada no Brasil, mas pouco estudada. O objetivo deste trabalho foi conhecer a natureza das características de interesse e selecionar plantas, para seguir o programa de melhoramento de feijão-vagem, por meio da análise biplot de genótipo x característica. O delineamento utilizado foi de blocos casualizados com quatro repetições e 17 genótipos. Foram feitas análise de variância, análise de componentes principais e os gráficos bilots para número de vagem por planta, número de sementes por vagem, número de sementes por planta, peso de sementes por planta, peso de 100 sementes, produtividade de grãos e produtividade de vagem. A análise de variância mostrou existência de variabilidade genética entre os genótipos. Produtividade de grãos, produtividade de vagens e peso de sementes por plantas são altamente correlacionados. O número de sementes por vagem tem correlação negativa com peso de vagem, peso de grãos e peso de sementes por planta. Os genótipos Feltrin e UENF 14-30-3 foram indicadas para obtenção de ganhos para as variáveis produtividade de grãos e produtividade de vagem.

ABSTRACT: The green bean (Phaseolus vulgaris L.) is a nutrient-rich vegetable much appreciated; although, little studied, in Brazil. The aim of the current study was to investigate the nature of traits of interest, as well as to select plants for the green bean breeding program based on genotype vs. trait biplot analysis. The experiment followed a randomized block design, with 4 repetitions and 17 genotypes. Analysis of variance, principal component analysis and biplot charts were performed to analyze the number of pods per plant, the number of seeds per pod, the number of seeds per plant, seed weight per plant, 100-seed weight, as well as grain and pod yields. The analysis of variance showed genetic variability between genotypes. Grain yield, pod yield and seed weight per plant were highly correlated. The number of seeds per pod was negatively correlated with pod weight, grain weight and with seed weight per plant. Lines Feltrin and UENF 14-30-3 were indicated to increase gains in variables such as grain yield and pod yield.