There are three chromosome sets ( 3n= 21 )in PMCs of the autotriploid in barley. During the initial meiosis, the frequencies of trivalents and uni-valents observed are 70.46% and 29.54% respectively.At the first division, four types of chromosome disjunction could be observed. 7 : 14; 8 : 13; 9 : 12; and 10 : 11. Univaleuts usually become lagging chromosomes. At the second division, the lagging chromatids fail to be included in the telophase Ⅱ nuclei and result in micronuclei formation. The tripolar figuree...