Combined selection in early generation testing of self-pollinated plants

Abstract

Seven selection indexes based on the phenotypic value of the individual and the mean performance of its family were assessed for their application in breeding of self-pollinated plants. There is no clear superiority from one index to another although some show one or more negative aspects, such as favoring the selection of a top performing plant from an inferior family in detriment of an excellent plant from a superior family<br>São apresentados os estimadores dos coeficientes de sete índices de seleção, que levam em consideração o valor fenotípico do indivíduo e o desempenho médio de sua família, e discute-se o uso destes índices em teste de geração precoce, no melhoramento de plantas autógamas. Não há clara superioridade de nenhum índice, embora alguns apresentem um ou mais aspectos negativos, como favorecer à seleção de planta excepcional em família de desempenho inferior, em detrimento de planta com desempenho desejável, em família superio

Predicted and realized gains of different selection strategies in soybean populations: a comparative study

“…A large b2/b1 ratio indicates a large influence of non-genetic factors within families. The smaller variation of nongenetic factors within families characterizes one of the main disadvantages of this combined selection index, because an exceptionally good individual belonging to a bad family can be selected, as pointed out by Viana and Cruz (1997). The procedure used to estimate the variance components can be another factor that increases the possibility of discarding the best individuals when using the combined index under the condition of high within family heritability.…”