Seed Production in the First Eight Years and Frequency of Natural Selfing in a Simulated Jack Pine Seedling Seed Orchard

Seed production and percent of natural selfing were determined in an 8 x 8-foot, 1200-tree plantation. Actual seed production was determined through age 6; production through age 8 was projected based on first-year cone counts at age 7. The percent of natural self-pollination, production of seedlings from natural selfing, and percent of selfs that were lethal were determined by marker seedlings. Ovulate strobili production began at 17 months of age; by age 4 a few trees produced small quantities of mature cones and seed. By age 8 years most trees produced an average of 39 mature cones per tree, 26,200 cones per acre, or 655,000 filled seed per acre, Total filled seed per acre produced through age 8 years was 1,159,000. The overall average of open-pollinated seedlings resulting from natural selfing was about 7 percent, The frequency of natural self-pollination, determined from carriers of selected seedling marker types, ranged up to 34 percent; on the average more than half of these were lethal. Removing trees showing high selfing percentages and careful culling of poorer seedlings grown from orchard seed before field planting should reduce the impact of natural selfing on wood yield in such plantations to a minimum.

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Author(s): Thomas D. Rudolph

Publication: Tree Improvement and Genetics - Lake States Forest Tree Improvement Conference - 1977