Genetic interactions between wheat and rye genomes in triticale : 2. Morphological and yield characters.

Six primary triticale lines were produced from two advanced breeding lines of Triticum durum and three inbred genotypes of Secale cereale. The wheat and rye parents as well as the triticale derivatives were then crossed each within the same group of species in all possible combinations. Parents, F1s, and F2 populations were used to study the inheritance of a set of morphological and yield characters. The results suggest that, in general, in triticale allelic interactions within the wheat and the rye components are suppressed in favour of intergenomic interactions. Heterozygosity in the rye genome appeared to be detrimental for triticale, whereas heterozygosity in the wheat genome only resulted in positive interactions between certain characters. The retention of a high level of heterosis for kernels per spike in the F2 generation of such hybrids indicates interactions between genes which are in the homozygous state in the rye but remain in the heterozygous state in the wheat genome. If heterozygosity in the wheat component occurs between genes in the A and B genomes (homoeoalleles), it can be fixed in true breeding lines. This condition may ultimately lead to the fixation of their benefical effect on the interaction between wheat and rye genome. Aneuploidy caused a significant decline in performance for most of the investigated characters.