CYTOGENETIC BEHAVIOR OF THE INTERSPECIFIC HYBRID OF MANIHOT NEUSANA NASSAR AND CASSAVA, M-ESCULENTA CRANTZ, AND ITS BACKCROSS PROGENY

An interspecific hybrid between cassava, Manihot esculenta Crantz, and M. neusana Nassar and the backcrossed progenies was examined meiotica lly and mitotically. The F-1 hybrid showed irregular meiosis due to un paired chromosomes. The backcrossed progeny ranged in fertility from 1 7.7 to 35.8%. Meiotic restitution was also observed in all of the hybr ids. Diploid pollen formation also occurred and ranged from 0.6 to 1.6 %. Irregular meiosis among the F-1 hybrid produced aneuploidy in backc rossed progeny. When the F-1 hybrid was used as the maternal plant in backcrosses with cassava, this improved seed setting in the BC1 progen ies, whereas the reciprocal backcross produced sterile progenies.