Meiosis and pollen stainability in Prunus avium L. cv. Lambert

Variation in pollen viability and the meiotic behaviour of sweet cherry Prunus avium L. cv. Lambert were studied. Pollen viability was estimated using aceto-carmine. Three types of pollen grain were observed; large, triangular; small, aborted; and intermediate. Only the first type were considered to have been viable at time of blossom harvest. No significant differences were detected between trees, between branches, or within branches, except for a North and South branch of one tree. Highly significant differences were detected among blossoms in a bud. The relative frequency of abnormal pollen was 42.26 per cent. Premeiotic budwood was stored at -5°C. Subsequent forcing at 10°, 15°, 20°, and 25°C to bring the buds to meiosis, and staining in alcoholic hydrochloric acid-carmine, revealed meiotic abnormalities at all temperatures except 15°C. Early meiotic division stages of additional material forced at this temperature were synchronous, but asynchrony developed after first metaphase. The first meiotic division was characterized by the frequent presence of a single pair of univalents, which appeared to arise from desynapsis of a bivalent in diplotene. Meiotic abnormalities associated with the univalents were observed at later division stages. The metaphase-anaphase division was typified by sequential disjunction of the bivalents, characteristic for sweet cherry meiosis. The relative frequency of abnormal first meiotic divisions was 45.49 per cent.Land and Food Systems, Faculty ofGraduat