Department of Genetics & Plant Breeding, Bidhan Chandra Krishi Viswa Vidyalaya, Kalyani-741 235, Nadia, West Bengal, India
*Part of Ph.D. thesis submitted to the University of Kalyani by the senior author.
P. aconitifolius (2n=22) and P. trilobus (2n=22) were crossed reciprocally. Viable seeds were produced only in the P. aconitifolius ♀ × P. trilobus ♂ combination. The F1 had 5.7% pollen fertility and was completely seed sterile. Colchicine induced amphidiploids had 89-7% pollen fertility. The F1 (2n= 22) showed the occurrence of one quadrivalent in a few cells. Inversion loops, duplication loops and delayed separation of bivalents were also observed. The amphidiploid (2n=44) showed fairly regular meiosis though one quadrivalent was noted in 18% of the PMC's scored. The post-zygotic isolating mechanisms operating between these two species are: hybrid inviability, weakness and sterility. The hybrid sterility is segregational in nature. It is suggested that the chromosomes of these two species are differentiated through translocations, inversions and duplications.
