Abstract
The seven primary trisomics of Pennisetum americanum were isolated in the progeny of triploid. Based on their specific morphological features the trisomics were named as Papery, Semidwarf, Narrow long leaf, Rolled, Tiny, Necrotic and Narrow dwarf. Most of the phenotypic characters studied in the trisomics showed a correlated variation. The extra chromosome prensent in the trisomics acted in a specific way affecting the anatomy, physiology and morphology of the trisomic plant resulting in a well defined trisomic phentotype which made them distinct from each other as well as from the disomics. The meiotic behaviour especially the trivalent formation and chiasma frequency showed variation in the trisomics. The presence of an extra chromosome in the trisomics was found to bring about an interchromosomal effect on the formation of chiasma by other chromosomes in the complement. The interrelationships between various meiotic events like trivalent formation, chiasma frequency, anaphase separation, micronuclei formation and pollen fertility in respect of specific extra chromosome have been discussed.
