Cytological microevolutive changes in hexaploid triticale (X Triticosecale Wittmack)

The objectives of this study were to evaluate a) the success in meiosis of disruptively selected triticale progenies used as recurrent selection parents, and b) the changes that took place in their meiotic behavior after three cycles of recurrent selection in hexaploid triticale. From samples of five immature spikes per experimental unit, the meiotic index (MI) and the percentage of tetrads containing micronuclei in 1, 2, 3 or 4 microspores were estimated. The families used as recurrent selection parents showed a significantly higher MI than those with the lower agronomical performance. A positive and significant linear relation between the MI and cycles of recurrent selection was observed. The analysis of the tetrads with micronuclei showed a non-significant positive tendency to increase the percentage of tetrads with micronuclei in 1 microspore in the more evolved cycle, while negative linear relations between tetrads with micronuclei in 2, 3 and 4 microspores and cycles were observed. These results suggest that in triticale those individuals with superior reproductive performance tend to reduce their meiotic irregularities.