中文摘要：

四川牡丹Paeonia decomposita和块根芍药Paeonia intermedia具有共同的第五号染色体减数分裂异常：与长臂相比,短臂在遗传距离和物理距离之间存在巨大的背离。短臂的遗传距离约是长臂的1/28（块根芍药）和1/50（四川牡丹）,短臂的物理距离约是长臂的1/3,物理距离是遗传距离的9倍以上。在四川牡丹中,五号染色体的环形二价体（两个臂形成交叉）和棒状二价体（仅一个臂形成交叉）的比率是1.94：98.06,而在块根芍药中是3.42：96.58。在这两个种中,棒状二价体大大多于环形二价体。四川牡丹和块根芍药第五号染色体的后期I倒位桥出现频率非常低,而且断片长度是变化的。

英文摘要：

This study revealed that there were common meiotic abnormalities on the fifth pair of chromosomes in Paeonia decomposita and P. intermedia. Short arms had a tremendous deviation between genetic distance and physical distance, when compared with the long arms. The genetic distance of the short arm was about a twenty-eighth （P. intermedia） and fiftieth （P. decomposita） of the long arm, whereas the physical distance was about one third of the long arm and the physical distance was over nine times longer than the genetic distance. In P. decomposita, the ratio between ring bivalents （both arms formed chiasma） and rod bivalents （only one arm formed chiasma） was 1.94 ： 98.06, whereas in P. intermedia the ratio was 3.42 ： 96.58. In both of the species, rod bivalents were much more than ring bivalents. Occurrence frequency of anaphase Ⅰ bridges was low in P. decomposita and P. intermedia, and the length of fragments varied in a range.