Abstract: Using the squashing technique, meiosis and pollen development of Picea koraiensis were investigated. Our results showed that meiosis of Picea koraiensis started in spring and last about 2-3 months. The main configuration of bivalents was the ring ones caused by more than two times of chromosome exchanges on the arms. The rod-bivalents produced by chromosome exchange at only one arm were rarely observed. The microscopic appearance of meiosis in this species showed pronounced diffuse stage between pachytene and diplotene. Cytokinesis of Picea koraiensis is simultaneous type, resulting in tetrahedral tetrads. However, tetrad configurations were also affected by the orientations of the second meiotic axes leading to the formation of different shaped tetrads. At metaphase II, the spindle axis was occasionally oriented parallel to each other instead of perpendicular as expect theoretically, then the four haploid nuclei were kept in a transitory syncytium in tetragon. After callose wall was dissolved, independent single-nucleus pollens formed. After then, the haploid nucleolus underwent three cycles of mitotic division, resulting in the formation of four-celled pollen with two prothallial cells, one body cell and one tube cell. The pollen development of Picea koraiensis is similar to that recorded in Pinus.

Key words: Picea koraiensis Nakai, meiosis, pollen Mother Cell (PMC), pollen development, chromosome