PHENOTYPIC AND GENETIC-VARIATION IN THE SEED MATURITY OF SCOTS PINE

Scots pine (Pinus sylvestris L.) seed matures poorly in northern areas , which causes great problems for forest regeneration. Variation in an atomical seed maturity between individuals and years was studied in 2 natural northern populations (67 degrees N and 68 degrees N), one of w hich was a timber line population. The amount of genetic variation in anatomical seed maturity was estimated in 2 test sites at different la titudes (62 degrees N and 66 degrees N) for 2 years. The test sites ha d identical genotypes cloned by grafting. The variation in the seed ma turity between individuals in the timber line population was consisten t over the years (correlations between years 0.61 to 0.67). Genetic va riation was most clearly expressed in northern conditions (broad-sense heritability, H = 0.79, SD = 0.06; H = 0.73, SD = 0.08) where problem s caused by poor seed maturity are the most severe. In the southern te st site, the heritabilities were lower due to almost complete seed mat urity. High broad-sense heritabilities suggest that seed-maturing abil ity should be regarded as an important character in selecting clones f or seed production in northern conditions.