Wheat lines could be clustered into different groups based on their agronomic traits, or general combining ability (GCA) of agronomic traits, or molecular markers. Hybrids from parents in different groups were generally superior to most hybrids from parents in the same group. But there were apparent differences in heterosis for different heterotic groups based on different methods. This study showed that the average heterosis of heterotic groups based on RAPD markers is much higher than that of heterotic groups based on yield components and GCA of these traits. GCA had little value in clustering parents for predicting heterosis. Molecular markers would be the first choice for developing heterotic groups in wheat.

In order to develop genic male-sterile lines with a blue seed marker, male-sterile plants, controlled by a dominant nuclear gene Ms2, were used as female parents against a 4E disomic addition line`Xiaoyan Lanli' (2n 44, AABBDD4EII) as the male parent to produce monosomic addition lines with blue seed. Male-sterile plants from the monosomic addition lines were pollinated with durum wheat for several generations and in 1989 a male-sterile line with the blue grain gene and the male-sterile gene Ms2 on the same additional chromosome was detected and named line 89-2343. Using this line, the blue seed marker was successfully added to a short male-sterile line containing Ms2 and Rht10. The segregation ratios of male sterility and seed colour as well as the chromosome ®gurations of dierent plants indicated that the blue grain genes, Ms2 and Rht10 were located on the same additional chromosome. Cytological analysis showed that the blue marker malesterile lines in durum wheat and common wheat were monosomic with an additional chromosome 4E. The inheritance ratio for blue seed male-sterile plants and white seed male-fertile plants was 19.7% and 80.3%, respectively, in common wheat. The potential for using blue marker sterile lines in population improvement and hybrid production is discussed.