Abstract: This study put forward the approach of using monoploidy pollen(1n) as a reference to observe and test 2n pollen vitality of White populars by vivi-fertilization, and found the reasons of low rate of acquired triploids. The results showed that although 2n pollens had a certain germi-nating ability, the germinating process of natural and artificial 2n pollens was tardier than that of 1n pollens, and 2n pollens had weaker competition in mixed pollination than 1n ones. It was the radical reason of very low rate of acquired triploids in breeding practice. Moreover, the germi-nating of 20% to 35% of the 2n pollens induced by Colchicine showed innormalcy, which also af-fected the rate of acquired triploid breeding.

Key words: Popelus tomentosa