Genetic and environmental variation in seed, cone and progeny characteristics of black spruce clones in a northern Ontario seed orchard

Abstract

Genetic and environmental variance in cone and seed properties and early progeny growth of Picea mariana (Mill.) B.S.P. clones were evaluated using cones and seed from two to three ramets of 19 clones each growing in a northern Ontario grafted clonal seed orchard. A cone analysis and a germination test were conducted to estimate variation among clones and among ramets within clones. Variation in growth of 19 open-pollinated families growing under two fertilizer regimes in a greenhouse was evaluated after three, four and five months of test establishment. Mean cone volume and mean cone length were found to be 2.2 cm[superscript 3] and 24.4 mm, respectively. The mean for number of seed per cone was 71, although only 18% of these seeds were filled. Nested analyses of variance indicated that clones accounted for 23% to 39% of the total variation in cone size and seed yield per cone. Variation among ramets within clones for these characteristics accounted for 13% to 19% of total variance. The average germination percent, based on filled seed, was 68% and was completed (90%) after 11 days. Genetic variance in germination percent and germination speed acccounted for 67% and 21% of the total variance, respectively. For germination percent and germination speed, 18% and 33% of the total variation, respectively, were due to ramets within clones. In the progeny test, family heights were highly significant at all three ages. At five months family height means ranged from 30 cm to 34 cm and from 11 cm to 14 cm at the low and high fertilizer level, respectively, Ramet-within-clone effects were only significant after three and four months, when seedling heights were significantly correlated with seed weights. Family-fertilizer interactions were not significant at all three ages, although the variance component for this source of variation increased substantially towards the end of the test period.