Resumos
Foram feitos cruzamentos recíprocos entre as variedades AF-28, resistente à mosquinha-do-sorgo, e Sart, suscetível. A geração F1 derivada desse cruzamento foi quase tão danificada - nota de dano: 8,5 - quanto o pai suscetível Sart - nota de dano: 9,2. O pai resistente teve nota 1,2. Isso mostra que a suscetibilidade à mosca é dominante ou parcialmente dominante. O comportamento de famílias derivadas de plantas F2 e cultivadas na geração F3 sugere que, no mínimo, dois pares de genes recessivos são responsáveis pela herança da resistência à mosquinha. A variedade resistente AF-28 apresenta diversas características indesejáveis: colmo seco; muito tardia; não-ereta; panícula muito aberta e muito alta. Sua resistência à mosquinha, todavia, pode ser transferida facilmente e recombinada com características agronômicas desejáveis. Obtiveram-se linhas resistentes, mais baixas, precoces, eretas, com. colmo sucoso e panículas mais fechadas.
Reciprocal crosses were made between the sorghum varieties AF-28 resistant to the sorghum midge, and Sart susceptible. In 1975 under field conditions at Campinas, State of São Paulo, Brazil, the average damage of the Fl of these crosses was 8.5, the average damage of Sart was 9.2 and of AF-28 was 1.2 showing that susceptibility to sorghum midge is dominant or incompletely dominant. Inflorescences of F2 plants were bagged at random and F2 derived families in the generation F3 (S1 lines) were studied under field conditions in 1977. Fourteen families out of a total of 216 from the cross Sart x AF-28, did not differ significantly at the 5% level from the resistant parent AF-28. The chi-square between the observed ratio of 14:202 and the expected ratio of 14:210 was not significant. This result fits into the hypothesis of a minimum of two genes governing the resistance to sorghum midge in the variety AF-28. Three families out of a total of 109 from the cross AF-28 x Sart did not differ significantly at the 5% level from the resistant parent AF-28. The observed ratio of 3:106 does not fit properly into the expected ratio of 3:45 for two pairs of genes or into the expected ratio of 3:189 for 3 pairs of genes. The hypothesis that a minimum of 2 recessive pairs of genes are responsible for the resistance to the sorghum midge in the variety AF-28 is still sustained by the observed ratio 3:106. The lowest mean damage observed among the F3 families was 0.86 in the cross AF-28 x Sart while the mean damage of the resistant parent was 0.79. The lowest damage among the F3 families from the cross Sart x AF-28 was 0.937 while the mean damage of the resistant parent AF-28 was 0.9027. There was no F3 line among the 325 observed, which had a mean damage equal or lower than the resistant parent. This suggests that at least 2 recessive pairs of major genes are responsible for the resistance, but other genes with minor effects might be present. Some lines derived from F3 families with low mean damage showed good agronomic characteristics together with good level of resistance showing that the resistance can be transferred and recombined to produce resistant cultivars or hybrids.
ARTIGOS
Herança da resistência da variedade de sorgo AF-28 a Contarinia sorghicola Coquillet 1 1 Trabalho apresentado no VI Congresso Brasileiro de Entomologia, Campinas (SP), de 3 a 9 de fevereiro de 1980. Agradecimentos são devidos ao CNPq, processo 200.471/80-AG, e ao Dr. Natal Vello.
Inheritance of resistance to Contarinia sorghicola Coquillet in the AF-28 sorghum variety
Carlos Jorge RossettoI; Toshio IgueII
ISeção de Entomologia Fitotécnica, IAC
IISeção de Técnica Experimental e Cálculo, Instituto Agronômico, IAC
RESUMO
Foram feitos cruzamentos recíprocos entre as variedades AF-28, resistente à mosquinha-do-sorgo, e Sart, suscetível. A geração F1 derivada desse cruzamento foi quase tão danificada nota de dano: 8,5 quanto o pai suscetível Sart nota de dano: 9,2. O pai resistente teve nota 1,2. Isso mostra que a suscetibilidade à mosca é dominante ou parcialmente dominante. O comportamento de famílias derivadas de plantas F2 e cultivadas na geração F3 sugere que, no mínimo, dois pares de genes recessivos são responsáveis pela herança da resistência à mosquinha. A variedade resistente AF-28 apresenta diversas características indesejáveis: colmo seco; muito tardia; não-ereta; panícula muito aberta e muito alta. Sua resistência à mosquinha, todavia, pode ser transferida facilmente e recombinada com características agronômicas desejáveis. Obtiveram-se linhas resistentes, mais baixas, precoces, eretas, com. colmo sucoso e panículas mais fechadas.
SUMMARY
Reciprocal crosses were made between the sorghum varieties AF-28 resistant to the sorghum midge, and Sart susceptible.
In 1975 under field conditions at Campinas, State of São Paulo, Brazil, the average damage of the Fl of these crosses was 8.5, the average damage of Sart was 9.2 and of AF-28 was 1.2 showing that susceptibility to sorghum midge is dominant or incompletely dominant.
Inflorescences of F2 plants were bagged at random and F2 derived families in the generation F3 (S1 lines) were studied under field conditions in 1977.
Fourteen families out of a total of 216 from the cross Sart x AF-28, did not differ significantly at the 5% level from the resistant parent AF-28. The chi-square between the observed ratio of 14:202 and the expected ratio of 14:210 was not significant. This result fits into the hypothesis of a minimum of two genes governing the resistance to sorghum midge in the variety AF-28.
Three families out of a total of 109 from the cross AF-28 x Sart did not differ significantly at the 5% level from the resistant parent AF-28. The observed ratio of 3:106 does not fit properly into the expected ratio of 3:45 for two pairs of genes or into the expected ratio of 3:189 for 3 pairs of genes. The hypothesis that a minimum of 2 recessive pairs of genes are responsible for the resistance to the sorghum midge in the variety AF-28 is still sustained by the observed ratio 3:106.
The lowest mean damage observed among the F3 families was 0.86 in the cross AF-28 x Sart while the mean damage of the resistant parent was 0.79. The lowest damage among the F3 families from the cross Sart x AF-28 was 0.937 while the mean damage of the resistant parent AF-28 was 0.9027. There was no F3 line among the 325 observed, which had a mean damage equal or lower than the resistant parent.
This suggests that at least 2 recessive pairs of major genes are responsible for the resistance, but other genes with minor effects might be present. Some lines derived from F3 families with low mean damage showed good agronomic characteristics together with good level of resistance showing that the resistance can be transferred and recombined to produce resistant cultivars or hybrids.
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Recebido para publicação a 7 de maio de 1982.
- 1. BASSETT, M. J. & WOODS, F. E. A procedure for combining a quantitative inheritance study with the first cycle of a breeding program. Euphytica, 27:295-303, 1978.
- 2. BERGQUIST, R. R.; ROTAR, P.; MITCHELL, W. C. Midge and anthracnose head blight resistance in sorghum. Tropical Agriculture, Trinidad, 51(3): 431-435, 1974.
- 3. ROSSETTO, C. J.; BANZATTO, N. V.; IGUE, T. Comportamento de variedades de sorgo em relação a Contarinia sorghicola e Rhopalosiphum maidis em diferentes épocas de plantio. Bragantia, Campinas, 35:365-374, 1976.
- 4. WIDSTROM, N. W.; WISEMAN, B. R.; McMILLIAN, W. W. Some gene effects conditioning resistance to midge and webworm injury in sorghum. Sorghum Newsletter, 15:22-23, 1972.
Datas de Publicação
-
Publicação nesta coleção
17 Dez 2007 -
Data do Fascículo
1983
Histórico
-
Recebido
07 Maio 1982
