Studies on the chromosomes of solanum surettense

The structure of the pachytene chromosomes ofSolanum surettense Burm. f. (=S. xanthocarpum Schrad. & Wendl.) have been studied in detail. Morphological data on the total lengths, arm ratios and the extents of differentiation into heterochromatic and euchromatic regions on each of the arms of the twelve chromosomes constituting the haploid set for the species, have been presented. It is seen that identification of the individual members of the chromosome complement becomes possible only when the pattern of differentiation are read together with their total lengths and arm ratios. A comparison of the pachytene chromosomes ofS. surettense with those ofS. torvum, another member of the spinous group of nontuberous Solanums, has shown that no two chromosomes of these species have common morphological features, and that the two species are cytologically as distinct as they are on taxonomic criteria.