The cytogenetics of the differences between some<i>Secale</i>species

Abstract

1. The seed of crosses of Secale cereale with S. montanum and S. dalmaticum germinated only when S. cereale was the seed parent. 2. S. cereale was found to differ from S. montanum and S. dalmaticum by two large translocations involving three pairs of chromosomes, and a small translocation involving a fourth pair. The fertility of the F 1 plants was low, and in ear morphology and perennial habit they were similar to the S. montanum and S. dalmaticum parents. 3. S. montanum and S. dalmaticum were found to be similar in gross chromosome structure and their hybrids were phenotypically intermediate and fertile. 4. The F 2 of the cross S. cereale x S. dalmaticum consisted of three types, in terms of chromosome structural condition and plant morphology, those like one or other parent and those like the F 1 . 5. The genetic and evolutionary significance of this situation is discussed, together with the problem of the fixation of translocations in populations.