The comparison of wheat-rye and wheat-<i>Aegilops</i>amphidiploids

Abstract

1. The diploid species Secale cereale (2 n = 14) is self-incompatible, Aegilops longissima (2 n = 14) and A. caudata (2 n = 14) are self-compatible. A. longissitna is usually self-pollinated and A. caudata is usually out-pollinated. 2. Meiotic behaviour, constancy of chromosome number and seed fertility have been examined in the three octoploid amphidiploids derived from crosses of Triticum vulgare variety Holdfast (2 n = 42) with S. cereale A. longissima and A. caudata respectively. 3. All the amphidiploids had cells in which some chromosomes were unpaired at first metaphase of meiosis. This meiotic irregularity is not, therefore, related to the breeding system of the diploid parent. 4. The fertility of the amphidiploids was not related to their meiotic regularity. 5. The least fertile amphidiploid was derived from the self-incompatible diploid S. cereale . The most fertile amphidiploid was derived from the selfcompatible, self-pollinating diploid, A. longissima . 6. It is suggested that the infertility of the wheatrye amphidiploid may result from interactions between genotypes adapted to different breeding systems, rather than from the homozygosity in the amphidiploid of deleterious recessive genes derived from the outbreeding rye parent. 7. The demonstration of the independence of meiotic regularity and fertility will complicate selection work on wheat-rye amphidiploid material.