Een cytologisch onderzoek aan eenige soorten en soortsbastaarden van het geslacht saccharum

cum laude graduation (with distinction)

Within the wild cane, Saccharum spontaneum, 56 bivalent chromosomes are found in a regular division of pollen mother cells, indicating a somatic chromosome number 112.

Several well known varieties of sugar-cane, S. officinarum, appeared to have 40 chromosomes in the haploid phase and 80 in the somatic phase. But in these canes, meiosis was often seriously disturbed, reducing the fertility. This was also so with the very thin Indian canes Chunnee and Ruckree 11, having 90-91 chromosomes somatically.

In relation to the reduced fertility of S. officinarum, it was remarkable that hybrids between S. officinarum (n = 40) and S. spontaneum (n ~ 56) were very fertile, since usually hybrids between species with different chromosome numbers are partly fertile or totally sterile. However the hybrids between the above species did not have 40 + 56 = 96 chromosomes, but 40 + 40 + 56 = 136 chromosomes. This was also so for Kassoer, a similar interspecific hybrid found wild, that was especially used for hybridization with S. officinarum..

Cytological research of Kassoer and the hybrids from crosses of S. officinarum with S. spontaneum demonstrated that 68 bivalents could be counted in the metaphase of reduction division.

The doubling of the S. officinarum chromosomes from 40 to 80 is probably due to longitudinal splitting of the S. officinarum chromosomes during fertilization in the zygote, thus providing (2 x 40) + 56 = 136 chromosomes.