Abstract
Shoot production rates, shoot abortion rates, and pattern of abortion were observed in crown tops of oak (Quercus mongolica Blume var. grosseserrata Rehd. et. Wils.: QM) canopy trees from 1992 to 1994. Among three years, shoot production rates (number of produced shoots per 1-yr.-old branch) were ranged 1.7-1.9. A year was divided into leafing and leaf less season, then shoot abortion rate was determined for each season. Shoot abortion rate was about 20% per season (ranged 14-23%), except extraordinary value as 44% of Tree 1 at leafing season in 1993. Almost half of the shoots were aborted annually. Aborted shoots were classified into three morphological types. Single shoot abortion (type 1) shared considerable proportion of abortion. Most of type 1 abortion was occurred on lateral shoots. Another abortion type, abortion of live monopodial branches attached to current shoots (type 2), was abundant in 1-yr.-old branch, and secondly frequent in 2-yr.-old branch. High turnover rate of shoots in crown tops of QM canopy trees was suggested.
