Cytological Characterization and Pollen Viability Studies in the Interspecific Hybrids between Helianthus Annuus and Helianthus Maximiliani

The present investigation was undertaken with a view to study Cytological behavior of F1 interspecific hybrids of diploid wild perennial species Helianthus maximilini (2n = 34) and with cultivated sunflower Helianthus annuus (2n = 34) prebred line M-106. The interspecific hybrids have annual life cycle with the diploid somatic chromosome number thirty four. Chromosome association represented by univalents, bivalents, trivalents, besides the formation of normal bivalents, numerous irregularities observed during diakinesis and metaphase I of hybrids. In addition to these several types of chromosome irregularities like chromosome bridges and fragments, laggards and micronuclei were also noticed in considerable number of PMCs. The pollen viability of these F1 hybrids is very less compared to their parent, may be due to irregular behavior of chromosomes during meiosis in addition to environmental effect. The performance of these hybrids was either superior or nearer to their cultivated parent, but percentage of seed set of the two hybrids is low compared to parent, the existence of negative correlation of pollen fertility and chromosome abnormalities could explain low seed set. As due to these processes, narrow genetic base of the cultivated sunflower gets broadened with the infusion of genes from wild species.