Estimacion de los parametros geneticos en la yuca

The importance of estimating genetic parameters in cassava in order to produce superior performing cv. is highlighted. Different concepts related to phenotypic variance are discussed; variance is divided into genetic (additive, dominance, epistasis) and environmental. Of the former, additive variance is most important in plant breeding. The statistical models developed to estimate genetic variance are indicated. Other concepts discussed are heritability and its estimation (based on regression or on components of variance) and correlated factors. Finally, the results of different studies carried out to estimate the components of variance in cassava or the heritability in the crop are reviewed, as well as correlated characters. It is concluded that further studies are needed to elucidate which types of gene action are involved in the expression of major agronomic characters. In future expt., care should be taken to assure that sampling is adequate for environmental conditions and that plant competition is representative of commercial production. It is evident that some characters depend more on nonadditive genetic effects than others; dominance and epistatic effects are important in the expression of root yield and yield components. (CIAT)