Cytogenetics of Fragment Chromosomes in Barley

EVERAL types of fragment chroiiio~onies have been found in a ma-S terial of barley grown at our institute for cytogenetical research purposes.A triploid plant fotind in 1956 w a ' ~ selfed.I n its progeny a number of plants were found having different chroniosonie numbers.Plants with 14 to 27 chromosomes appeared.In 1958 it was found that two of the 15-clironiosome plants had each produced one plant having 14 normal chromosomes plus one centric fragment.These two fragments were denoted fr, and fr,.In the progeny of anolher trisoniic p1:int a third type of fragment was found in 1959.This was named f r , (ISING, 1961).When selfing these plants with extra fragments, individuals 1i:iving two fragments of the same type were found.In the present study fragments of the types fr, and fr, were investigated. J. THE TRANSMISSION OF THE FRAGMENTSCrosses were undertaken between normal plants and such having 1 or 2 extra fragments.The results are given in Table 1.As seen from the table there is a certain degree of elimination of fragmenls from one generation to the nest.However, when comparing the transmission of the fragments with that of supernumerary chromosomes of the normal set, one must conclude that the elimination is surprisingly low.In two cross combinations gametes having two extra fragments had functioned.