Problems in breeding and cytology of sugar cane

Abstract

In Part V the phenomenon endo-duplication of chromosomes within embryo-sac mother cells—cause of the increase in chromosome number within species hybrids of Saccharum—was discussed.

Special cases of change in chromosome number by hybridization of sugar cane, which formerly were inconceivable, appeared to be based on endo-duplication.

In Saccharum species hybrids with an increased chromosome number equalling twice the haploid number of the female parent plus once the haploid number of the male parent, are of such a frequent occurrence that they may be called normal.

Also within other genera interspecific and intergeneric hybrids are known of which the somatic chromosome numbers show the same kind of increase. They are, however, less numerous than in Saccharum. Of agricultural plants we know them for instance in Solanum (potato), in intergeneric hybrids between Lolium and Festuca and in hybrids between Triticum monococcum and T. turgidum. In horticultural plants they occur in Cyclamen. About the mode of origin of such hybrids opinions are not uniform. In this article the possibility is considered whether the chromosome increase in such hybrids may be interpreted in the same way as in Saccharum.