THE TIMING OF BUD SET IN SEEDLINGS OF PICEA-ABIES FROM SEED CROPS OF A COOL VERSUS A WARM SPRING AND SUMMER

Seedlings from bulked seed lots of 2 seed orchards from a cold (1981) and a warm (1989) seed year were tested for differences in bud-set in 8 controlled environment chambers and 3 nurseries. Seedlings of the 19 87 seed lot formed terminal buds at shorter nights in growth chambers, and they formed buds Earlier under natural day lengths in the nurseri es, than seedlings from the 1989 seed lot. Time of flowering in spring was 17 days earlier in 1989 than in 1987 because of the mild winter a nd early spring of 1989. The results thus show that seed crops from di fferent seed years may perform differently for adaptiv properties. It is suggested that night length and temperature during meiosis, pollina tion and fertilization and/or differences in temperature during the se ed maturation period can affect the photoperiodic response of seed orc hard progeny.