¹Department of Agronomy, Zhejiang Agricultural University, Hangzhou 310029, China

Correspondence: Jun Zhu, E-mail: jzhu@zjau.edu.cn

²Permanent address: Department of Agronomy, Henan Agricultural University, Zhengzhou 450002, China

Received 29 April 1998; Accepted 12 October 1998.

Abstract

A method is proposed for predicting potential heterosis of offspring of crop hybrids by an additive, dominance and additive additive model (ADAA). By using unbiased predictors of additive and dominance, as well as additive additive effects, general formulae for predicting heterosis over mid-parent and heterosis over the better parent are derived for different generations. When there exists genotype by environment (GE) interaction, formulae are also derived for predicting interaction heterosis. Heterosis in a specific environment is the sum of heterosis arising from the main genotypic effect and that arising from GE interaction deviation. The epistasis heterosis (_AA) could play an important role in the use of heterosis for both an F₁ hybrid and its later generations. In addition, a simple formula is given for predicting the number of generations of a cross that would still keep a certain level of heterosis over the better parent. Data from a diallel cross of cotton are analysed as a worked example for predicting genotypic value, heterosis, and the number of generations for each cross when heterosis over the better parent is larger than 5%.