EFFECT OF SEED MOISTURE ON WYOMING BIG SAGEBRUSH SEED QUALITY

Seed germination and seedling vigor of Wyoming big sagebrush (Artemisi a tridentata Nutt, ssp, wyomingensis) were evaluated following manipul ation of seed moisture, a practice benefiting many species, At the tim e of harvest, seed moisture ranged from 2.3 to 9.0% for 5 collections tested and seeds with moisture between 5 to 6% had the highest and mos t rapid germination. Seed moisture changed during storage, but germina tion percentage was not affected by post-harvest seed moisture change, indicating that germination is related more to habitat or genetic var iations than the initial moisture content, Seedling vigor increased af ter storage, suggesting that after-ripening may be required, Seeds of 2 commercial collections were subsequently humidified at 2, 5, 10, and 15 degrees C for up to 15 days, or to 60% moisture content. Seed mois ture increased most gradually at 2 degrees C and seeds held at 10 degr ees C attained a higher moisture level than at other temperatures, Ger mination percentage, germination rate, and seedling vigor were similar between treatments and controls regardless of seed moisture change, I mbibition temperature did not affect germination percentage or seedlin g vigor, hut the time to 50% germination decreased with increasing inb ibition temperature. We conclude that artificial seed moisture managem ent did not affect germination percentage, germination rate, or seedli ng vigor of this species when tested under optimum moisture conditions , Germination is more related to habitat or genetic variables than ini tial seed moisture content.