Abstract: A pruning test has been carried out in a 12-year-old seed orchard of Pinus koraiensis clonal for heightening per unit yield of seeds at Cao He kou since 1981. The pruning technique which promoted fruitage obviously had been used in a intermediate trial. The results indieated that the pruning conducted one month before flowing of sap, cutting out the main shoot and maintaining 3 to 5 leteral branches among the upper branches to be used as future multi-branch of maternal tree, can yaise the fructification amount up 40% than that of the trees which were not pruned at that stage.

Key words: Pinus koraiensis seed orchard, Pruning technique, Promoting fructification, Tree dwarfing