| Generally in crosses of T. Spelta from Iran with T. Spelta
from Europe no segregations were observed in characteristics of T. Spelta.
Only in a few progenies some freethreshing plants appeared which corresponded
to the compactum-, subcompactum- and squarehead-types. The
same types but in a much larger extent were observed in F3 and
F3 of a cross between T. Spelta from Asturia with a distinct
line of T. Macha. The segregated freeshreshing types proved to be
rather constant. Now their cytogenetical analysis is under investigation.
It can be concluded from the studies carried hitherto that the genetical basis of Spelta-characteristics is the same with T. Macha, T. Spelta Europe and T. Spelta Iran. However the occurence of small structural chromosomal differences must be assumed to cause disturbances in the meiosis of hybrids between different Spelta-types and to lead to the formation of the observed chromatin bridges. Therefore chromosomal rearrangements could result in the origin of freethreshing types. Probably the chromosome IX is favoured to undergo rearrangements, as in this the Q-factor, the suppressor of Spelta-characteristics, and the B-factor, the supprressor of awns, are located. Although T. Spelta Asturia and T. Macha are awned some of their hybrids proved to be awnless resp. short-awned, and only in the progenies of these awnless hybrids the segregation of compactum and other freethreshing types were observed. From the findings of T. Spelta in Iran and their cytogenetical behaviour the conclusion can be drawn that the culture of T. Spelta in Iran does not trace back to imports from Europe; but both Spelta-types could derive from a common origin. However T. Spelta should be regarded as the original form of the cultivated hexaploid wheats, not as one of the derived form of hexaploid naked wheats (T. aestivum). There are several possibilities for the origin of freethreshing wheat from Spelta wheat. For example, a genetically possible mechanism revealed in the experiments of the author is the crossing of different hexaploid Spelta-forms, from which a large number of naked types with tough rachis arose. |
| <-- Back |