MEIOSIS AND POLLEN GRAIN VIABILITY IN HELIANTHUS-MOLLIS, HELIANTHUS-SALICIFOLIUS, HELIANTHUS-MAXIMILIANI AND THEIR F1 HYBRIDS WITH CULTIVATED SUNFLOWER

Three diploid perennial sunflower species are useful for variety improvement: Helianthus mollis, because of sessile leaves, H. salicifolius, because of a high oil concentration, and H. maximiliani, a potential source of resistance to Sclerotinia sclerotiorum. The crossability of these species to cultivated sunflower was examined. Hybrids were obtained from eight combinations, with 3-15 F-1 plants per combination. The F-1's exhibited the dominant phenotype of the wild species. Pollen viability varied between 32.1 and 69.9%. Meiosis was irregular in the F-1 hybrids. At diakinesis, bivalents (62.7-97.9% of meiocytes), univalents (0-31.23%), and multivalents (3.84-7.68%) were detected. At anaphase I, chromosome bridges were detected in 6.77 to 11.44% of meiocytes. Fast chromosomes in metaphase I, and lagging chromosomes in anaphase I and telophase II were evidenced in a high percentage of meiocytes.