Estimativas de parâmetros genéticos à seleçao na populaçao de arroz irrigado CNA 1

In 1993/94, 97 families S 0:2 from the CNA 1 rice (Oryza sativa L.) populations were evaluated at Embrapa-CNPAF experimental station, Goianira, Brazil. The rice cultivars BR-IRGA 409, Javaé and the CNA 1/0/1 were used as checks. Each plot consisted of three rows 4 in long, 0.20 in spaced between in a triple square latice 10x10. The objectives of the present study were to evaluate the breeding potential of CNA 1 population through estimation of genetic parameters and expected response to direct and indirect selection as well as expected response based on classical selection according to Smith (1936) and Hazel (1943) the index. Grain yield, leaf blast, plant height, number of spikelets per panicle and percentage of filled grains showed high variability, expressed by the coefficient of variation. Among the seven traits evaluated, percentage of filled grain and dry weight of 100 seeds showed high and positive genotypic correlation to grain yield indicating that these traits have to be considered as priorities in a breeding program to increase grain yield. Expected response in grain yield, based on classical selection index, was similar to expected response on direct selection for this trait. However, with the selection index, positive response to selection is expected for leaf blast resistance, indicating the possibility to enhance grain yield and blast resistance simultaneously. eng