Pollen development in relation to phenological stages of inflorescence expansion in Amelanchier alnifolia (saskatoon), with a comparison with buds forced out of dormancy
A relationship was developed between phenological stages of inflorescence expansion and the internal development of pollen within the anther of Amelanchier alnifolia Nutt. flowers. The major microscopic events associated with microsporogenesis and microgametogenesis were correlated with seven stages of external inflorescence development in both natural buds and those forced from dormancy in different concentrations of gibberellin at various times of the year. In fall and early spring, it was found that gibberellin at a concentration of 2.5 mg/L forced buds to produce inflorescences that most resembled those from natural field populations. However, it was not possible to force flower buds to develop all the way to anthesis. Flower bud development stopped when the pollen was at the binucleate stage. Despite this limitation, the ability to force buds increases the time frame for the study of many aspects of the reproductive biology of A. alnifolia.Key words: microsporogenesis, microgametogenesis, gibberellin, GA, flowering.