GENETIC-VARIATION IN JUVENILE GROWTH AND PHENOLOGY IN A WHITE SPRUCE PROVENANCE PROGENY TEST

We investigated the distribution of genetic variation among and within provenances, the extent of genetic control in growth and bud phenolog y traits and potential of early testing of height growth for 285 open- pollinated families from 57 provenances of white spruce (Picea glauca) from Quebec and Ontario. Provenances and families within provenances showed significant genetic variation in seedling growth, 1-year branch number, 3-year budset and 8-year height, but not in 3-year bud-burst. On average, provenance variance was as large as family-within-provena nce variance. Individual heritabilities for all traits were generally low (range 0.08 to 0.19) and family heritabilities were higher (range 0.17 to 0.45). In 3-year-old seedlings, height growth was positively c orrelated with budset, indicating that selection for greater 3-year he ight would delay budset. Nonsignificant family-within-provenance-by-si te interaction variance and high genetic correlations in 8-year height among test sites suggest that families were stable across environment s. If the best 20% of families were selected and mated in a seed orcha rd, predicted genetic gain for 8-year height would be 8%. Strong genet ic correlations between 8-year height and seedling heights indicate th at 8-year height could be predicted reliably from seedling heights.