Data/hora: 17/06/2024 19:28:54

Biblioteca(s): | Embrapa Milho e Sorgo.
Data corrente: | 13/10/1997
Data da última atualização: | 13/07/2018
Autoria: | SANTOS, M. X.; MIRANDA FILHO, J. B.
Afiliação: | EMBRAPA/CNPMS.
Título: | Genetic potential of two Brazilian races of maize (Zea mays L.) for breeding purposes.
Ano de publicação: | 1992
Fonte/Imprenta: | Journal of Genetic and Breeding, New Delhi, v. 46, p. 83-90, 1992.
Idioma: | Inglês
Conteúdo: | Two Brazilian races of maize, CRAVO and ENTRELAÇADO, were considered exotics in the sense that they are poorly adapted in the State of São Paulo (Brazil). Their peculiar characteristics are large number of kernel rows (thick ear) in CRAVO and long (thin) ear in ENTRELAÇADO. Samples of the two races were crossed with the local and adapted population ESALQ-PB1 (E) and lhe segregating populations were designated by EC and EE, respectively. The effect of introgression in EC and EE was a decrease in mean yield of the order of 7.3% and 20.2%, respectively, for ear yield on the average of two locations. For grain yield the decreases were 5.0% and 29.0%, respectively. The ear length was 11,1% lower in EC and 6,2% higher in EE, and the kernel row number was 17.9% higher in EC and also 5.7% higher in EE. The estimates of the additive genetic variance for ear yield from the combined analysis of two locations were 100.48,186.16 and 283.02 (g/pl)2 in E, EC and EE, respectively. For ear length, the estimate in EE (191.61 cm2)was 37.4% and 99.1% higher than for E and EC. On the other hand, for kernel row number, the estimated additive variance in EC (220.87) was 96.09'% and 57.4% higher than E and EE, respectively. It was thus apparent that the increase in genetic variability due to introgression of exotic germplasms was more expressive for ear length in EE and for kernel row number in EC. For yield. the increase in genetic variability was more evident in EE (introgression of ENTRELAÇADO) than in EC (introgression of CRAVO). The expected mean after one cycle of half-sib selection for ear yield in percent of checks were 95.2%, 91 .3% and 82.7% in E, EC and EE, respectively. The expected mean for grain yield followed approximally the same trend. The expected means were algo given for mass selection in one sex. For ear length and kernel row number were also given for both selection schemes. The overalI results were encouraging in the sense that the introgression of exotic germplasms increased the genetic variability and the decrease in yield was not very expressive. The opportunities for selection for useful alIeles of non-specific traits are discussed.
Palavras-Chave: | Maize; Variabilidada genética.
Thesagro: | Melhoramento; Milho; Raça; Zea Mays.
Thesaurus Nal: | breeding; Corn.
Categoria do assunto: | G Melhoramento Genético
Registro original: | Embrapa Milho e Sorgo (CNPMS)

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