EFFECTS OF ROOT PRUNING AMD STEM INJECTIONS WITH GIBBERELLIN-A-4 7 ONFLOWERING AND CONE HARVEST IN 3 PICEA-ABIES SEED ORCHARDS/

The effects of root pruning and stem injections of gibberellin A 4/7 ( GA) on flowering and cone harvest were studied in three mature Picea a bies (L.) Karst. seed orchards. The trials were split into two consecu tive years, two in the summer of 1988, the third in summer 1989. Both years could be regarded as good years for natural induction of floweri ng. No effects were found on male flowering, whereas female flowering was enhanced by root pruning in two trials and by GA injections in one . No interaction effects on either male or female flowering were detec ted. In two trials, an approximately three-fold increase in number of cones per tree was obtained after root pruning and GA injections, whic h is a commercially acceptable increase.