Abstract
The fertile F1 plant (TcSF1-1) T. compactum (n=21)×S. cereale (n=7) and its offsprings were studied genetically and cytologically with the purpose of breeding the constant type in the descendants.
The number of somatic chromosomes of this F1 is 28, the sum of the gametic numbers of chromosomes of the parents.
The external characters of the F1 resembled more closely to T. compactum than being intermediate between the parents.
The maturation division in PMC-s of the F1 may be classified into two types A and B. A-type gives rise to the pollen grains having the number of chromosomes 28/2 or nearly so, and B-type results in the pollen grains with the number of chromosomes 2n or approximately so. In B-type non-conjugation and the formation of restitution nucleus were observed.
The pollen grains having 2n chromosomes, produced through the course of non-conjugation and restitution nucleus are provided with A B D genoms from T. compactum and R genom from S. cereale. These pollen grains play an important role in the formation of amphidiploid.
The number of somatic chromosomes of F2 plants were 47, 48, 54, 55, 56 and 58. In the F2 generations hypo and hyper amphidiploid plants resulted from the abnormality in the maturation division of F1 were frequently found besides the amphidiploids with 56 chromosomes.
