Resistance to Pratylenchus brachyurus in Vitis species population through multivariate approaches and mixed models

Genetically diverse interspecific hybrids of Vitis were selected for resistance to Pratylenchus brachyurus. Three segregating populations with 57 hybrid crosses were evaluated. The parents included Vitis romanetiiC166-043 × 07355-075, 06354-047 × Cereza and 06354-047 × Nocera, selected from the germplasm bank at the University of California, Davis, the United States. The experiment was arranged in a randomized block design, with three replications and three plants per plot. Root mass, nematodes per gram of root and reproduction factor were determined and used as quantitative variables; 16 multi categoric descriptors were also evaluated. The traits were analyzed using the Ward-Modified Location Model procedure (Ward-MLM) for the composition of genotype groups. Genetic parameters and prediction of genetic values by Restricted Maximum Likelihood / Best Linear Unbiased Prediction (REML / BLUP) were assessed. The Ward-MLM classification strategy supported the formation of three homogeneous groups. Group I comprised 13 hybrids; Group II, 26 hybrids; and Group III, 18 hybrids. Groups II and III contained hybrids resistant to P. brachyurus. High broad sense heritability values were found for root mass, reproduction factor and nematodes per gram of root, which provided genetic gain and allowed selection of resistant genotypes available for cloning, since the total genetic variance occurred due to the dominance effects. Of the 57 genotypes assessed, those with the lowest genotypic values for reproduction factor were selected as resistant, including: CH3.2, CH3.23, CH3.8, CH3.37, CH3.38, CH3.41, CH3.36, CH2.1, CH2.7, CH1.1, CH1.3 and CH1.2.

Resistance to Pratylenchus brachyurus in Vitis species population through multivariate approaches and mixed models

Genetically diverse interspecific hybrids of Vitis were selected for resistance to Pratylenchus brachyurus. Three segregating populations with 57 hybrid crosses were evaluated. The parents included Vitis romanetiiC166-043 × 07355-075, 06354-047 × Cereza and 06354-047 × Nocera, selected from the germplasm bank at the University of California, Davis, the United States. The experiment was arranged in a randomized block design, with three replications and three plants per plot. Root mass, nematodes per gram of root and reproduction factor were determined and used as quantitative variables; 16 multi categoric descriptors were also evaluated. The traits were analyzed using the Ward-Modified Location Model procedure (Ward-MLM) for the composition of genotype groups. Genetic parameters and prediction of genetic values by Restricted Maximum Likelihood / Best Linear Unbiased Prediction (REML / BLUP) were assessed. The Ward-MLM classification strategy supported the formation of three homogeneous groups. Group I comprised 13 hybrids; Group II, 26 hybrids; and Group III, 18 hybrids. Groups II and III contained hybrids resistant to P. brachyurus. High broad sense heritability values were found for root mass, reproduction factor and nematodes per gram of root, which provided genetic gain and allowed selection of resistant genotypes available for cloning, since the total genetic variance occurred due to the dominance effects. Of the 57 genotypes assessed, those with the lowest genotypic values for reproduction factor were selected as resistant, including: CH3.2, CH3.23, CH3.8, CH3.37, CH3.38, CH3.41, CH3.36, CH2.1, CH2.7, CH1.1, CH1.3 and CH1.2.(AU)

Avaliação da germinação e dormência de sementes de arroz vermelho e branco / Germination and dormancy of red and white rice seeds

As sementes de arroz branco possuem dormência, porém de intensidade menor que as de arroz vermelho. Entretanto, já foram observados alguns genótipos de arroz vermelho com dormência de intensidade semelhante à de sementes de arroz branco. Após o estádio de maturidade fisiológica, a semente pode ficar exposta a condições menos favoráveis. Com isso, os objetivos deste trabalho foram determinar o estádio de maturidade fisiológica e monitorar a germinação e a dormência, aos 0,30 e 60 dias após a colheita, de sementes de genótipos de arroz vermelho e de arroz branco. O delineamento experimental para a determinação do ponto de maturidade fisiológica foi o de blocos ao acaso em parcelas subdivididas com cinco repetições. Os dados foram submetidos à análise de regressão. Para avaliação da germinação e dormência em cada época de armazenamento foi feita a análise da variância conjunta, segundo o delineamento experimental em blocos ao acaso em esquema fatorial 4 (genótipos) x 3 (1 controle e 2 tratamentos de quebra de dormência), com cinco repetições. A comparação de médias foi realizada pelo teste de Student-Newman-Keuls a 5% de probabilidade. A maturidade fisiológica das sementes dos genótipos Vermelho Pequeno, Vermelho Virgínia, SCSBRS Tio Taka e EPAGRI109 é atingida no estádio duro. O período de 30 dias de armazenamento é suficiente para a superação da dormência das sementes do genótipo Vermelho Pequeno e para os genótipos Vermelho Virgínia, EPAGRI109 e SCSBRS Tio Taka o período necessário é de 60 dias de armazenamento.

White rice seeds have dormancy, but of lower intensity than red rice seeds. However some red rice genotypes have been observed with similar intensity to the dormancy of white rice seeds. After the physiological maturity stage, seeds can be exposed to less favorable conditions. Thus, the objectives were to determine the physiological maturity stage and to monitor germination and dormancy at 0, 30 and 60 days after the seed harvest of red and white rice genotypes. The experiment to determine the physiological maturity stage was a completely randomized block subdivided into plots and five replications. Data was obtained by regression analysis. Germination and dormancy data in each storage period was submitted to variance analysis, according to a completely randomized block design, analyzed as a 4 (genotypes) x 3 (1 and 2 control treatments break dormancy) factorial, with five replications. Means were compared by the Student-Newman-Keuls at 5% probability level. Physiological maturity of seeds from rice genotypes Vermelho Pequeno, Vermelho Virgínia, SCSBRS Tio Taka and EPAGRI109 is reached at dent stage. A 30-day storage period is efficient at overcoming the seed dormancy of the Vermelho Pequeno genotype but a 60-day period is required by the other genotypes.

Avaliação da germinação e dormência de sementes de arroz vermelho e branco / Germination and dormancy of red and white rice seeds

As sementes de arroz branco possuem dormência, porém de intensidade menor que as de arroz vermelho. Entretanto, já foram observados alguns genótipos de arroz vermelho com dormência de intensidade semelhante à de sementes de arroz branco. Após o estádio de maturidade fisiológica, a semente pode ficar exposta a condições menos favoráveis. Com isso, os objetivos deste trabalho foram determinar o estádio de maturidade fisiológica e monitorar a germinação e a dormência, aos 0,30 e 60 dias após a colheita, de sementes de genótipos de arroz vermelho e de arroz branco. O delineamento experimental para a determinação do ponto de maturidade fisiológica foi o de blocos ao acaso em parcelas subdivididas com cinco repetições. Os dados foram submetidos à análise de regressão. Para avaliação da germinação e dormência em cada época de armazenamento foi feita a análise da variância conjunta, segundo o delineamento experimental em blocos ao acaso em esquema fatorial 4 (genótipos) x 3 (1 controle e 2 tratamentos de quebra de dormência), com cinco repetições. A comparação de médias foi realizada pelo teste de Student-Newman-Keuls a 5% de probabilidade. A maturidade fisiológica das sementes dos genótipos Vermelho Pequeno, Vermelho Virgínia, SCSBRS Tio Taka e EPAGRI109 é atingida no estádio duro. O período de 30 dias de armazenamento é suficiente para a superação da dormência das sementes do genótipo Vermelho Pequeno e para os genótipos Vermelho Virgínia, EPAGRI109 e SCSBRS Tio Taka o período necessário é de 60 dias de armazenamento.(AU)

White rice seeds have dormancy, but of lower intensity than red rice seeds. However some red rice genotypes have been observed with similar intensity to the dormancy of white rice seeds. After the physiological maturity stage, seeds can be exposed to less favorable conditions. Thus, the objectives were to determine the physiological maturity stage and to monitor germination and dormancy at 0, 30 and 60 days after the seed harvest of red and white rice genotypes. The experiment to determine the physiological maturity stage was a completely randomized block subdivided into plots and five replications. Data was obtained by regression analysis. Germination and dormancy data in each storage period was submitted to variance analysis, according to a completely randomized block design, analyzed as a 4 (genotypes) x 3 (1 and 2 control treatments break dormancy) factorial, with five replications. Means were compared by the Student-Newman-Keuls at 5% probability level. Physiological maturity of seeds from rice genotypes Vermelho Pequeno, Vermelho Virgínia, SCSBRS Tio Taka and EPAGRI109 is reached at dent stage. A 30-day storage period is efficient at overcoming the seed dormancy of the Vermelho Pequeno genotype but a 60-day period is required by the other genotypes.(AU)