Cytological studies on several species of potato I. The somatic chromosome and meiotic chromosome behaviour in diploid species^|^ang; Tayam

In the present study the idiogram in root-tips and the meiotic chromosome behaviour of pollen mother cells in the diploid potato species a n g ; Tayam e q u i v ; were investigated. The somatic chromosome number of this species is 24; among them 2 pairs of large chromosome have one satellite respectively; the members of one pair of chromosomes are unequal in size; and the other 9 pairs are small and nearly of the same size.Irregularities of chromosome behaviour in meiosis and in pollen grain formation have been described. Special attention was given to the preceding of one pair of chromosomes and, also to the appearance of both normal and abortive pollen grains corresponding to changes of temperature during sporogenesis. As a result of these investigations, the irregularity of meiosis and the formation of abortive pollen grains are ascribed to the hybrid nature of this species demonstrated in the idiogram and externally to high air temperature.The hypothetical two chromosome sets seem to have high affinity but it is, however, easily disturbed by daily high air temperature during sporogenesis as ascertained in the meiosis occuring in the month of July.