RESUMO

The objective of this study were to estimate the general ability and specific combining ability in ten wheat genotypes in two generations (F1 and F2) to indicate parents and hybrid combinations that are promising to achieve new favorable combinations. Ten wheat genotypes were hybridized in a complete diallel, without reciprocals, totaling 45 hybrid combinations. F1 hybrids and the F2 populations and parents were evaluated in a randomized block design with three replicates in spaced plant. The effect of general combining ability (GCA) was greater than specific combining ability (SCA) in both generations, regardless of the characters evaluated. The best performances of the CGC to grain yield per plant (GYP), number of kernels per spike (NKS), number of spikes per plant (NSP) and plant height (PH) were observed for the parents Fundacep 50, Pampeano, BRS Figueira and UTF 0605, respectively. Promising hybrid combinations (high magnitude of SCA in both generations and high average for the character and at least one parent presenting desirable GCA) were selected. The association of GCA with the performance of characters GYP (F1 = F2 = 0.75 and 0.81), NKS (F1 = F2 = 0.61 and 0.60) and PH (F1=0.99 and F2= 0.98) showed to be a reliable criterion for choice of parents, regardless of generation evaluated.

 O trabalho teve como objetivo estimar a capacidade geral e específica de combinação de dez genótipos de trigo em duas gerações (F1 e F2) a fim de indicar genitores e combinações híbridas promissoras. Dez genótipos de trigo foram hibridados em forma de dialélo completo, sem os recíprocos, totalizando 45 combinações híbridas. Os híbridos F1, populações F2 e os genitores foram avaliados em delineamento de blocos casualizados com três repetições, em planta espaçada. O efeito da capacidade geral de combinação (CGC) foi superior à capacidade específica de combinação (CEC) em ambas às gerações para todos os caracteres avaliados. O melhor desempenho da CGC para rendimento de grãos por planta (RGP), número de grãos por espiga (NGE), número espigas por planta (NEP) e estatura de planta (EP) foi observado para os genitores Fundacep 50, Pampeano, BRS Figueira e UTF 0605, respectivamente. Combinações híbridas promissoras (elevada magnitude da CEC em ambas as gerações, média elevada  para o caráter e pelo menos um dos genitores apresentando CGC desejável) foram selecionadas. A CGC foi positivamente associada com o desempenho dos caracteres PGP (F1=0,75 e F2=0,81), NGE (F1=0,61 e F2=0,60) e EP (F1=0,99 e F2=0,98) em ambas as gerações avaliadas, indicando ser um critério confiável para escolha de genitores.

RESUMO

Adjustment of seeding schemes is one of the crop management techniques that most influences grain yield components. This work aimed to characterize the potential grain yield and its components in wheat (Triticum aestivum L.) genotypes with contrasting tillering ability under different seeding densities and environments. Five experiments were conducted in split-plot design, each with ten cultivars (main plot), sown in five distinct seeding densities (subplots). Experiments were sown in three locations in southern Brazil in the years 2005, 2006 and 2007. The grain yield per plot and its yield components: number of fertile tillers, weight of 1,000 grains, ear weight and number of grains per ear were evaluated. Genotypes with reduced tillering ability expressed an increase in grain yield with an increase in seeding densities, however showing a reduction in ear weight. The number of grains per ear did not affect grain yield but was highly influenced by seeding densities. The compensatory effect was expressed by the weight of a thousand grains as a function of the experimental conditions in which the genotypes were evaluated, regardless of seeding densities used. Results pointed to differences among cultivars tested in specific locations and years.

RESUMO

The objective of this study were to estimate the general ability and specific combining ability in ten wheat genotypes in two generations (F1 and F2) to indicate parents and hybrid combinations that are promising to achieve new favorable combinations. Ten wheat genotypes were hybridized in a complete diallel, without reciprocals, totaling 45 hybrid combinations. F1 hybrids and the F2 populations and parents were evaluated in a randomized block design with three replicates in spaced plant. The effect of general combining ability (GCA) was greater than specific combining ability (SCA) in both generations, regardless of the characters evaluated. The best performances of the CGC to grain yield per plant (GYP), number of kernels per spike (NKS), number of spikes per plant (NSP) and plant height (PH) were observed for the parents Fundacep 50, Pampeano, BRS Figueira and UTF 0605, respectively. Promising hybrid combinations (high magnitude of SCA in both generations and high average for the character and at least one parent presenting desirable GCA) were selected. The association of GCA with the performance of characters GYP (F1 = F2 = 0.75 and 0.81), NKS (F1 = F2 = 0.61 and 0.60) and PH (F1=0.99 and F2= 0.98) showed to be a reliable criterion for choice of parents, regardless of generation evaluated.

O trabalho teve como objetivo estimar a capacidade geral e específica de combinação de dez genótipos de trigo em duas gerações (F1 e F2) a fim de indicar genitores e combinações híbridas promissoras. Dez genótipos de trigo foram hibridados em forma de dialélo completo, sem os recíprocos, totalizando 45 combinações híbridas. Os híbridos F1, populações F2 e os genitores foram avaliados em delineamento de blocos casualizados com três repetições, em planta espaçada. O efeito da capacidade geral de combinação (CGC) foi superior à capacidade específica de combinação (CEC) em ambas às gerações para todos os caracteres avaliados. O melhor desempenho da CGC para rendimento de grãos por planta (RGP), número de grãos por espiga (NGE), número espigas por planta (NEP) e estatura de planta (EP) foi observado para os genitores Fundacep 50, Pampeano, BRS Figueira e UTF 0605, respectivamente. Combinações híbridas promissoras (elevada magnitude da CEC em ambas as gerações, média elevada  para o caráter e pelo menos um dos genitores apresentando CGC desejável) foram selecionadas. A CGC foi positivamente associada com o desempenho dos caracteres PGP (F1=0,75 e F2=0,81), NGE (F1=0,61 e F2=0,60) e EP (F1=0,99 e F2=0,98) em ambas as gerações avaliadas, indicando ser um critério confiável para escolha de genitores.

RESUMO

Adjustment of seeding schemes is one of the crop management techniques that most influences grain yield components. This work aimed to characterize the potential grain yield and its components in wheat (Triticum aestivum L.) genotypes with contrasting tillering ability under different seeding densities and environments. Five experiments were conducted in split-plot design, each with ten cultivars (main plot), sown in five distinct seeding densities (subplots). Experiments were sown in three locations in southern Brazil in the years 2005, 2006 and 2007. The grain yield per plot and its yield components: number of fertile tillers, weight of 1,000 grains, ear weight and number of grains per ear were evaluated. Genotypes with reduced tillering ability expressed an increase in grain yield with an increase in seeding densities, however showing a reduction in ear weight. The number of grains per ear did not affect grain yield but was highly influenced by seeding densities. The compensatory effect was expressed by the weight of a thousand grains as a function of the experimental conditions in which the genotypes were evaluated, regardless of seeding densities used. Results pointed to differences among cultivars tested in specific locations and years.