Marcos Fontoura de Carvalho

Caracterização de famílias mutantes de arroz para tolerância ao frio nos períodos vegetativo e reprodutivo

Low temperatures that occur during the cultivation of rice in the Southern region of Brazil cause reductions in to the yield and quality of the rice grain. Genotypes tolerant to low temperatures would be an alternative to minimize these problems. In the present work cold tolerance was evaluated in rice families (M4 generation) in the vegetative and reproductive phases, in order to identify possible genetic variability. For the evaluation in the vegetative stage, 10 seeds from each family were placed in cell trays and kept at 13 oC for 10 days in controlled chamber with 12 hour day light. The evaluation at the reproductive stage consisted of the application of low temperature at anthesis, by a stress of 15 oC for 7 days. The results suggest that in the vegetative phase, 6 families presented 0-20% reduction in stature, showing a high degree of tolerance. For the reproductive phase there were no families showing higher tolerance than the tolerant control.

Correlação de acamamento com rendimento de grãos e outros caracteres de interesse agronômico em plantas de trigo

The selection in yield primary components and lodging resistance with goal of increasing grain yield can represent efficient strategies for optimizing genetic gain in wheat. In this sense, the objective of the present work was to detect characters that enable the identification of high grain yield potential and lodging resistant genotypes through the use of indirect selection. The experiment was conducted at the Centro Agropecuario da Palma, Capao do Leao/RS, consisting of nineteen wheat genotypes arranged in random block design with three replications. In this work conditions the hectoliter weight can be efficiently used through indirect selection aiming at increasing grain yield, average grain weight, number of grains per ear and ear weight. The character ear weight showed high indirect effect on grain yield and can be used for indirect selection due to its ease of measurement. The line TB 951 is indicated as an excellent source for lodging resistance in wheat, and can contribute to increase ear length, number of spikelets per ear, ear weigh and number of grain per ear.

Diversidade e estrutura genética para virulência de três populações sul brasileiras de Puccinia coronata

Studies on the genetic diversity and structure of pathogen populations by mean of known resistance genes are important as they allow the direct access to virulence/avirulence genes of individuals in target populations. Therefore, the goal of this work was to characterize the genetic diversity and structure of three Puccinia coronata f. sp avenae Fraser & Led populations from the State of Rio Grande do Sul by using a standard phenotypical assay of virulence/avirulence of 40 isolates to 25 Pcs genes. The results indicated that despite of the high variability for virulence of Southern brazilian isolates, the population showed a moderate genetic diversity, mainly as a function of the high virulence presented by the isolates. Basically, no difference was found in the frequency of virulence genes among the isolates collected in Capao do Leao, Eldorado do Sul and Passo Fundo counties, suggesting that the pathogen populations are not structured. The results indicated the need of a strategy for disease control in these three locations.