Investigations in the Triticinae III. The morphology and field behaviour of theA2generation of interspecific and intergeneric amphidiploids

1. In general the juvenile growth of interspecificTriticumand intergenericTritioum-Aegilopsamphidiploids, was normal and did not deviate from the parental behaviour. However, in the case of the interspecific hexaploids derived fromT. monococcumandT. aegilopoidesthere was an early check in growth, and all the amphidiploids derived fromA. caudatadeveloped more or less severe chlorosis.2. Most amphidiploids were intermediate between their parents in mature plant characters. However, in the hexaploidTriticuminterspecific amphidiploids there was a transgressive increase in plant height, and whilst the derivatives ofTriticum x Aegilopscrosses fell within the range of their parents, they were closer to one or other parent depending upon theAegilopsspecies involved.3. The ear morphology of theTriticuminterspecific amphidiploid was generally a composite of that of the parents, the influence of each parent being detectable. In theTriticum-Aegilopsamphidiploids, however, ear morphology was so strongly influenced by theAegilopsspecies, that there was frequently no obvious difference between the ears of amphidiploids with a commonAegilopsparent but different wheat parents.4. The fertility of the amphidiploids was low and there was no significant correlation between the fertility of amphidiploids and parents. There was a significant correlation between both the grain weight, and number of spikelets per ear, in parents and amphidiploids, but whilst the mean grain weight was about that of the parent with the heavier grain, the mean of spikelets per ear was about that of the parent with the fewer spikelets.