Cytogenetical Evaluation of the Progenies of a Trispecific Hybrid in Pennisetum

SUMMARY

The trispecific hybrid P. squamulatum x amphidiploid (P. typhoides x P. purpureum) bad 2n=48 chromosomes. The pairing of chromosomes in meiosis revealed the existence of homology of chromosomes of the parental species.

Thirteen F₂ plants raised from the self pollinated panicles of this trispecific hybrid showed variation in morphological attributes in respect of height, stem thickness, size of leaf, hairiness of leaves, panicle size and density of spikelets. In gross morphology, plants similar to P. squamulatum, trispecific hybrid, F1 of P. typhoides x P. purpureum and P. purpureum are noticed in the F₂. None of these plants, however, had resemblance to P. typhoides.

The chromosome numbers (2n) varied among these F₂ plants as 36, 42, 43, 46, 48 to 52 and 57. The pollen fertility ranged from 2.7 to 83.9%. The pairing of chromosomes in F₂ drawn from the constituent genomes of the trispecific hybrid confirmed the homology between the genomes with x=7 and x=9. The cytogenetical evaluation of this dibasic hybrid also confirmed the interrelationships between species of different morphological sections in the genus Pennisetum. Multivalent associations, laggards and chromatin bridges at anaphase I constituted most of the abnormalities encountered in meiosis in all the F₂ plants. There was no correlation between the chromosomal status, pollen fertility, meiotic abnormalities and morphological characters.