RESUMO -O sucesso de um programa de melhoramento de plantas autógamas depende da escolha de genitores capazes de produzir progênies com as características desejadas. Sendo assim, este estudo teve como objetivo determinar os valores das capacidades geral e específica de combinação de quatro genótipos de feijão para os caracteres estatura de planta (EP) em centímetros, altura de inserção do primeiro legume (IPL) em centímetros, diâmetro do colo (DC) em milímetros, número de legumes por planta (NLP) e número de grãos por legume (NGL), a fim de avaliar o potencial destes como genitores para uso em programas de melhoramento. Quatro genitores de feijão (BAF07, BAF09 e IPR Uirapuru do grupo comercial preto e BAF50 do grupo comercial carioca) foram hibridados em um dialelo completo para a obtenção dos híbridos F 1 e recíprocos. O desempenho dos genitores, híbridos F 1 e recíprocos foi avaliado a campo em um experimento em blocos casualizados, com duas repetições, durante a safra agrícola de 2009/10. Para análise dialélica foi utilizada a metodologia proposta por Griffing (1956), método I, onde são incluídas n 2 combinações. O genótipo BAF07 pode ser empregado em blocos de cruzamentos quando o escopo do programa for aumentar os valores para EP, IPL, DC e NGL; foi possível observar ainda, através da magnitude dos componentes quadráticos a maior importância da capacidade geral de combinação, ou seja, dos efeitos aditivos no controle genético de características de importância agronômica em feijão. Palavras-chave: Phaseolus vulgaris L.. Capacidade de combinação. Melhoramento genético.ABSTRACT -The success of a breeding programme for autogamous plants depends on the choice of parents capable of producing progeny with the desired characteristics. Therefore, the objective of this study was to determine the values of the general and specific combining capabilities of four bean genotypes, for the characteristics: plant height (PH) in cm; height of insertion of the first pod (HIP) in cm; stem diameter (SD) in mm; number of pods per plant (NPP); and number of grains per pod (NGP); in order to assess their potential for use as parents in breeding programmes. Four bean parents (BAF07, BAF09 and IPR Uirapuru of the black commercial group and BAF50 of the carioca commercial group) were hybridized employing a complete diallel in order to obtain the F 1 hybrids and their reciprocals. The performance of the parents, F 1 hybrids and reciprocals was evaluated in the field in an experimental design of randomised blocks with two replications, during the 2009/10 crop season. For diallel analysis the methodology proposed by Griffing (1956) was used: Method I, where n 2 combinations are included. The BAF07 genotype can be used in blocks of crossings when the aim of the programme is to increase the values for PH, HIP, SD and NGP; it was also possible to observe a greater importance of the general combining capacity, by means of the magnitude of the quadratic components, i.e. of the additive effects in the genetic control of characteristics of agr...

In soybean, stink bugs are considered the most important pest insect as they feed directly from the grain, causing significant losses in seed yield and quality. The use of resistant genotypes is a promising strategy to control these insects. Focusing on selection of soybean lines with resistance and high yield potential, 251 recombinant inbred lines (RILs), derived from a cross between IAC‐100 (resistant) and CD‐215 (susceptible), were evaluated in two experiments, designed as alpha‐lattice, with three replicates in Piracicaba, during the growing seasons of 2012/13 and 2013/14. The evaluated traits were as follows: number of days to maturity (NDM), plant height at maturity (PHM), grain filling period (GFP), lodging (L), agronomic value (AV), grain yield (GY), weight of a hundred seeds (WHS), leaf retention (LR), and healthy seeds weight (HSW). Variance components were estimated by the Restricted Maximum Likelihood method (REML). Heritability and selection gain (SG) parameters were also calculated. Selection was carried out based on 2012/13 season, considering the genotypes that exhibited a minimum HSW of 2908.26 kg ha−1 (acceptable losses of 20% from the average GY). Insect population was monitored by cloth beating. An increase in stink bug population was observed during the grain filling period, with the highest population density occurring in the season 2012/13. Estimates of the variance components demonstrated the elevate influence of the interaction genotype x environment on GY and HSW, which exhibited the lowest estimates of heritability (23 and 34%, respectively). The estimate selection gain, calculated from the predicted means of GY and HSW, was of 665.4 and 482.4 kg ha−1 season 2012/13. Therefore, the applied selection allowed the identification of the genotypes exhibiting higher yields and resistance to the stink bug complex. From the RIL population, lines or genotypes potentially useful to generate novel cultivars were identified.

This study aimed to identify which is the main component of grain yield of bean that that shows less sensitivity effect of the environment, and provides greater consistency in the expression of

-Soybean plants with resistance to the stink bug complex are currently selected by extremely labor-intensive methods, which limit the evaluation of a large number of genotypes. Thus, this paper proposed the use of an alternative trait underlying the selection of resistant genotypes under field conditions with natural infestation: the weight of healthy seeds (WHS). To this end, 24 genotypes were evaluated under two management systems: with systematic chemical control of insects (management I), and without control (management II). Different indices were calculated using grain weight (Y P ) of management I and WHS of management II (Y S ). The high correlation between Y S and the indices mean productivity, stress tolerance and geometric mean productivity, plus the agreement in determining the groups of genotypes with resistance and high yield indicate that WHS is a useful character in simultaneous selection for these traits.

http://dx.doi.org/10.5007/2175-7925.2009v22n4p73No melhoramento de plantas é de grande importância a obtenção de ganhos genéticos para um conjunto simultâneo de caracteres agrícolas. O objetivo deste trabalho foi obter estimativas dos coeficientes de correlação fenotípica e avaliar os desdobramentos destas correlações em efeitos diretos e indiretos em relação aos diferentes métodos de semeadura realizados. Foram avaliados oito caracteres de importância agronômica (ciclo vegetativo, estatura de planta, inserção do primeiro legume, número de legumes por planta, número de grãos por legume; comprimento do legume, peso de mil grãos e o rendimento de grãos). Sendo utilizados três métodos de semeadura: i) semeadura em covas, ii) semeadura em linha cheia e iii) semeadura em linha com planta espaçada. O delineamento utilizado foi o de blocos casualizados com três repetições, sendo cada parcela composta por cinco linhas de quatro metros, com espaçamento de 0,5m. Os dados obtidos demonstram uma associação significativa e diferenciada entre o rendimento de grãos e os seus componentes em relação aos três métodos de semeadura, comparativamente. O caráter número de grãos por legume mostrou uma influência significativa na composição do rendimento de grãos independentemente do método de condução avaliado.