Meiotic Behavior in Several Brazilian Oat Cultivars(Avena sativa L.).

Considering that the production of grains is a characteristic closely related to meiotic behavior, the purpose of the present study was to evaluate some oat cultivars recommended for the southern region of Brazil in order to verify if tose which currently do not display a good performance present meiotic irregularities that might be impairing the production of viable gametes. The most common meiotic abnormalities were those related to the irregular segregation of chromosomes, characterized by the presence of precocious chromosome migration to the poles or laggard chromosomes and of non-oriented bivalents at the equatorial plate. In general, these chromosomes gave rise to micronuclei during telophase that remained until the tetrad stage. Another very common meiotic abnormality in all varieties was the occurrence of multiple bridges in anaphase I and II. Other less common meiotic abnormalities, such as cytomixis, mixoploidy and chromosome stickiness were observed in some varieties. Although meiotic abnormalities can cause pollen sterility, there was no correlation between these abnormalities and sterility. The percentage of sterile pollen grains was much lower than expected. The grains produced by the 12 cultivars ranged from 820 to 2601 kg/ha, showing no correlation with the rate of meiotic abnormalities or pollen fertility. Thus, the results obtained by cytological analysis suggest that the meiotic abnormalities were not the sole factors responsible for the decrease of productivity in the varieties analyzed.