Parâmetros genéticos de caracteres agronômicos em genótipos de mamoneira

The objective of this work was to evaluate the genetic parameters of agronomic traits in fixed and segregating populations of castor beans (Ricinus communis). The experiments were carried out between 2006 and 2009, with fixed and segregating populations obtained by crosses between the cultivars BRS 149 Nordestina, BRS 188 Paraguaçu, EBDA MPA 17, Mirante 10 and Sipeal 28. The evaluated traits were: plant height (EST), number of days from planting to flowering (FLO), number of fruit of three racemes (NFR), number of seeds of three racemes (NSR), and seed weight of three racemes (SWR). In the 'BRS 149 Nordestina' x 'Sipeal 28' cross, variances showed greater involvement of environmental effects and the heritability coefficients had values below 50%. In the 'BRS 149 Nordestina' x 'Mirante 10' cross, heritability varied between 24.6 (NFR) and 86% (FLO). In the 'BRS 188 Paraguaçu' x 'EBDA MPA 17' cross, values of heritability were low for all characters, except flowering. Genetic gain may be obtained by selecting for flowering precocity in most of the crosses studied. Artificial selection should be applied to advanced generations because the environment has a strong influence on the phenotypic traits. More rigorous breeding methods should be adopted for the segregating population, in order to obtain higher genetic gain.