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Abstract The objective of this work was to investigate the genetic control of black bean (Phaseolus vulgaris) and to select parents and segregating populations with high resistance to Fusarium wilt, high yield, and greater 100-seed weight (100SW), using a partial diallel cross. Twenty-five populations were obtained from two groups of parents – the first with five parents resistant to and the second with five parents susceptible to Fusarium wilt. The segregating populations were evaluated in experiments in three years/generations for reaction to Fusarium wilt, yield, and 100SW in an area naturally infested with the pathogen. The diallel analysis showed additive and nonadditive effects in control of the three studied traits, with predominance of additive effects. CNFP 15194, CNFP 15207, and 'BRS Esplendor' are the genotypes with high and negative general combining ability estimates (gi = -0.59, -0.76, and -0.13, respectively), being recommended for use as parents for resistance to Fusarium wilt. Among them, CNFP 15194 also forms populations with a greater 100SW (gi = 0.69). The BRS FP403 cultivar is recommended as a parent to increase yield (gi = 218) and 100SW (gi = 1.46). Six populations were selected to obtain black bean lines that combine resistance to Fusarium wilt, high yield, and high 100SW.

Our objectives were to evaluate general and specific combining ability (SCA) and genetic divergence among tropical maize inbred lines using single sequence repeat (SSR) markers. Thirteen inbred lines were crossed based on a complete diallel scheme. Hybrids and three checks were evaluated in a lattice experimental design. Silk and anthesis flowering, average plant height, average ear height, white spot (Pantoea ananatis) and gray leaf spot (Cercospora zeae-maydis) severity, and grain yield were evaluated. Significant differences (p < 0.05) for general and specific combining abilities were observed for all traits. Based on additive effects, inbred lines 1 (Flash) and 12 (SG 6015) were selected to reduce the flowering period and plant and ear height. Inbred lines 2 (CD 303) and 3 (AG 8080) were selected to reduce disease severity. For the simultaneous increase in grain yield and reduced severity of diseases, line 11 (AG 9090) as a parent or tester in topcross schemes is recommended. According to non-additive effects, crosses 2 (CD 303) × 13 (DKB 747) and 11 (AG 9090) × 12 (SG 6015) were selected for grain yield and future breeding programs. Six groups were identified using SSR markers; a major group contained six inbred lines. Because of the minor relationship between genetic divergence and SCA effects on grain yield limits, the use of the groups for future divergent crosses is recommended.

Foi avaliada a capacidade combinatória de oito cultivares de trigo, por meio de um esquema dialélico analisado segundo o modelo quatro da metodologia de Griffing. Paralelamente, foi realizada uma análise de dissimilaridade com marcadores SSR, a partir de estimativas de distância genética baseadas em pedigree. Oito características foram avaliadas num experimento delineado em blocos ao acaso, com duas repetições. O agrupamento das cultivares a partir das distâncias genéticas foi efetuado com os métodos UPGMA e Tocher. Ficou evidenciada a variabilidade entre os genótipos de trigo. As cultivares 'CD 108', 'CD 0542' e 'CD 104' apresentaram grande capacidade geral de combinação para vários caracteres. Os maiores valores de capacidade específica de combinação foram detectados nos híbridos mais heterozigotos, formados pelo cruzamento de parentais integrantes de grupos diferentes. Os agrupamentos indicados pelo pedigree não coincidiram com os indicados a partir dos marcadores moleculares. As distâncias dos marcadores SSR provavelmente refletem melhor as relações entre as cultivares de trigo do que as distâncias medidas com base na genealogia. A falta de associação entre os padrões de agrupamento foi provavelmente devida às propriedades intrínsecas de cada forma de estimação das distâncias genéticas, as quais podem modificar a interpretação e a distribuição da variabilidade genética entre os genótipos avaliados.The combining ability of eight wheat varieties was evaluated according to the fourth model of the Griffing's diallelic methodology. Studies on genetic dissimilarity based on microsatellite markers and genetic distance among genotypes from pedigree data were also performed. The experiment was carried out in a randomized block design with two replications. Eight traits were evaluated in the diallel. Genotypes were grouped according to the UPGMA and Tocher methods. Genetic variability among genotypes was evident. Varieties 'CD 108', 'CD 0542' and 'CD 104' were those who showed high values for general combining ability in several traits. Since the effects of specific combining ability were more important in those particularly heterozygous combinations obtained from varieties allocated in different clusters, field and molecular results coincided in a certain way. There was no a good coincidence between the dendrogram based on parentage coefficient and the one based on microssatellite markers. The very small association between standards of grouping was probably related to the intrinsic properties of each way of estimating the genetic distance, which can modify the interpretation and the distribution of the genetic variability in the evaluated genotypes.

We examined the heterotic parameterizations of diallel crosses among10 popcorn inbred lines in two different environments (municipalities of Campos dos Goytacazes and Itaocara, Rio de Janeiro State) and originating from tropical, temperate and subtropical germoplasm. Traits, including grain yield (GY), plant height (PH), ear height (EH), days to silking (FL) and popping expansion (PE), were measured. The inbred lines and the hybrids were evaluated in a randomized complete block design with three replications. The sources of genotypic variation, inbred lines and heterosis had significant effects on all traits. When the sources of heterotic variation were compared separately, estimated mean heterosis was found to be significant for all traits. When inbred lines and specific heterosis was investigated, only popping expansion was not significantly different, demonstrating that heterotic effects are favorable for developing superior hybrids. A direct relation between .i and i V. was made clear, especially for traits that were slightly influenced by the effects of dominance. Additivity was determined to have the best effect for improving popping expansion. The hybrid combinationshad positive estimates of heterosis for the GY but not for PE. The hybrids P1 x P3 and P2 x P4 had the best responses for the GY and PE. The superiority of the combination P1 x P3 shows that the addition of genomes with different edaphoclimatic adaptations is an important factor in obtaining superior hybrids.O presente trabalho teve com objetivo averiguar as parametrizacoes heteroticas de cruzamentos dialelicos entre dez linhagens de milho pipoca oriundas de genotipos tropicais, temperados e semi-temperados, em dois ambientes (municipios de Campos dos Goytacazes e Itaocara, Estado do Rio de Janeiro), em relacao as caracteristicas rendimento de graos; altura media de planta e da insercao da primeira espiga; numero medio de dias para florescimento e capacidade expansao. As linhagens e os hibridos foram avaliados em delineamento em blocos ao acaso, com tres repeticoes. Para as fontes de variacao linhagens eheterose houve significancia, pelo teste F, para todas as caracteristicas. No desdobramento da fonte de variacao heterose, estimativas de heterose media foram significativas para todas ascaracteristicas. Em relacao a heterose de linhagens e especifica, apenas a caracteristica capacidade de expansao nao expressou diferenca significativa, o que confirma que os efeitos heteroticos naosao favoraveis para sintese de hibridos com superioridade. A relacao direta entre .i e i V. ficou claro, especialmente para as caracteristicas pouco influenciadas pelos efeitos de dominancia. O efeito genico aditivo foi confirmado para capacidade de expansao. As combinacoes hibridas revelaram estimativas positivas de heterose para GY, mas nao para PE. Os hibridos P1 x P2 e P3 x P4 tiveram as melhores respostas para GY e PE. A superioridade da combinacao P1 x P3, demonstra que a adicao de genomas com adaptacao edafoclimaticas diferentes e importante para a obtencao de hibridos superiores.

Eight tropical maize populations were crossed in a diallel system. Parent and their 28 crosses were evaluated for grain yield in two plantations in 2006. The objective was to estimate the general combining ability (GCA) of the parental populations and the specific combining ability (SCA) of the crosses for grain yield. The populations were: 21, 22, 23, 25, 32, 43, 49 and the commercial variety VS-536. The Griffing method 2 design was utilized to estimate GCA and SCA effects, on a complete randomized block design with three replications, at two planting dates. The diallel analysis showed significant differences (P ≤ 0.01 y 0.05) among planting dates (PD), crosses (C), GCA, PD × C and PD × SCA interaction. Populations 23 and 43 showed the highest significant (P ≤ 0,01)  GCA, and the crosses VS 536 × Pob 32, Pob 22 × Pob 43, Pob 25 × Pob 49 y Pob 43 × Pob 49 showed the highest significant (P ≤ 0,01) SCA effects. Both high parent positive heterosis were observed for the crosses Pob 25 × Pob 49, Pob 43 × Pob 49 and Pob 22 × Pob 43. Populations 23 and 43 revealed potential to be used in maize breeding programs.

The number of branches per tree was analysed on F1 individuals originated in several crosses between apple cultivars with different architectural ideotypes: spur (Starkrimson, Golden spur), semispur (Liberty), weeping (Florina). The number of branches per tree in F1 hybrid apple, in their third year of vegetation, was different in six combinations, depending on the genotype of genitors, respectively on their architectural ideotype. There have been noticed significant differences among the tested cultivars used as genitors, the average of trait on hybrid combination being comprised between 4.28 in Goldenspur x Liberty and 7.14 in Starkrimson x Florina. A small number of branches per seedling were registered in Starkrimson x Goldenspur combination (4.32), where the both genitors are spur ideotypes. The variability of analysed characters was high, with s% between 33.9 at Liberty x Florina and 56.8 at Starkrimson x Liberty. These values suggest that seedlings with very different number of branches are likely to be identified in each combination. The analysis of variance for GCA and SCA has emphasised the fact that, in the studied apple combinations, both effects of general and specific combining ability contributed to the phenotypic expression of number of branches per tree. Goldenspur showed negative value for GCA, thus this could produce descendents with low vigour and number of branches, if they are used as genitors in apple breeding. Based on the values of general combining ability (GCA) and specific combining ability (SCA) selection of genitors can be very efficient for desirable characters of growth in apple breeding.

The utilization of diallel crosses for identification of superior combinations is a common practice in maize (Zea mays L.) breeding programs. This methodology allows the estimation of the combining ability of genotypes being evaluated. In this work, five inbred lines were evaluated as to their general (GCA) and specific (SCA) combining abilities, by using a complete diallel scheme. The single-crosses produced between these inbred lines were evaluated in seven environments, along with two checks, by using a randomized complete block design. Traits analized were: grain yield, plant height, ear height, ear placement, and prolificacy. A diallel analysis was carried out, following an adaptation of Griffing's method IV, in addition to hybrid stability and adaptability analyses. Significant differences were detected for entries and environments for all traits. The interaction genotype vs. environment was significant for all traits. GCA's were significant for all traits, while SCA's were non-significant only for ear placement. For grain yield, both additive (GCA) and non-additive (SCA) effects were important, while for the remaining traits additive effects were more important. The high yielding single-cross was obtained from the cross of lines L-08-05F and L-38-05D. Those inbred lines showed higher GCA's and their cross also had high SCA; also, it is responsive to environment improvements and reasonably stable. The second in rank high yielding single-cross, L-46-10D x L-08-05F, showed wide adaptability and stability.

We examined the heterotic parameterizations of diallel crosses among 10 popcorn inbred lines in two different environments (municipalities of Campos dos Goytacazes and Itaocara, Rio de Janeiro State) and originating from tropical, temperate and subtropical germoplasm. Traits, including grain yield (GY), plant height (PH), ear height (EH), days to silking (FL) and popping expansion (PE), were measured. The inbred lines and the hybrids were evaluated in a randomized complete block design with three replications. The sources of genotypic variation, inbred lines and heterosis had significant effects on all traits. When the sources of heterotic variation were compared separately, estimated mean heterosis was found to be significant for all traits. When inbred lines and specific heterosis was investigated, only popping expansion was not significantly different, demonstrating that heterotic effects are favorable for developing superior hybrids. A direct relation between ĝi and was made clear, especially for traits that were slightly influenced by the effects of dominance. Additivity was determined to have the best effect for improving popping expansion. The hybrid combinations had positive estimates of heterosis for the GY but not for PE. The hybrids P1 x P3 and P2 x P4 had the best responses for the GY and PE. The superiority of the combination P1 x P3 shows that the addition of genomes with different edaphoclimatic adaptations is an important factor in obtaining superior hybrids.