Crop & Pasture Science
In four aneuploid (2n = 39) plants of Sorghum almum the odd chromosome was involved in trivalent formation at first metaphase of meiosis more frequently than it was in an aneuploid (2n = 39) plant of S. halepense. Most of the gametes of the aneuploids had 19 or 20 chromosomes. Chromosome numbers of the progenies of these plants confirmed these observations, and also showed that the aneuploid lines could be maintained although in two of the S. almum lines there was selection for female gametes with the balanced number of n = 20. S, almum and S. halepense may be autotetraploid in origin. The differences in behaviour of the odd chromosome in the aneuploids are a reflection of the different levels reached in the differentiation of two pairs of preferentially pairing and genetically different chromosomes from each group of four homologues.