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 F₁ plants per combination. The F₁'s exhibited the dominant phenotype of the wild species. Pollen viability varied between 32.1 and 69.9%. Meiosis was irregular in the F₁ 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.     

Staining and fluorescent microscopy methods for pollen viability determination in sunflower and other plant species

Results shown in this paper imply a successful application of staining method by Alexander (1969) which is simplified in comparison to the original method and adapted for pollen viability estimation in sunflower, rapeseed, sugar beet, maize, wheat, alfalfa, etc. Aspects of research in which this method is frequently used are described.This paper also shows the results of fluorescent microscopy method (Kho and Baër, 1968) adaptation for pollen germination and pollen tube growth monitoring in sunflower, as well the possibility for its application in fertilization potential estimation.