Cytomorphology of the Progeny of a Raw Allopolyploid in <i>Pennisetum</i>

Abstract

A progeny of 210 plants raised from the selfed seeds of a raw allopolyploid (2n=42) of the parentage, Pennisetum typhoides (2n=14)×P. purpureum (2n=28) was analysed for variation. The method of metroglyph analysis was used. Segregants showing transgression in certain attributes over the values for the parental species were observed in the progeny as a consequence of genic segregation arising from the heterogenetic association of chromosomes of the constituent genomes. Inspite of fairly high degree of recombination, the population in general showed skewedness in distribution towards P. purpureum. There is a dominant bias for few attributes contributed by P. purpureum, while intermediate expression was observed for many others. The recombinants resembling amphiploid and P. purpureum occurred frequently. A cytological study of the progenies having pollen fertility ranging from 0 to 84 per cent has been made. The frequency of meiotic disturbances did not correspond to the extent of pollen sterility. The wide range of variation for pollen fertility in the progenies inspite of the meiotic stability and chromosome constancy points to the operation of genic factors controlling fertility. The role of cryptic structural hybridity in restoring recombinations and also in influencing the fertility-sterility status of the progenies has also been considered. The high meiotic stability of the progeny of the raw allopolyploid coupled with the facility for genic segregation is a welcome situation in the use of the hexaploids in back crossing programmes for improvement of the cultivated species.