REST PERIOD STUDIES ON SEEDS OF AMELANCHIER, PRUNUS, AND SORBUS

Abstract

Seed germinability based on chemical and embryo greening tests was used as a means for determining duration and cause of seed rest period in the species Amelanchier, Prunus, and Sorbus. Both procedures provided reliable means for quick estimation of viability. After-ripening at 2 °C was found to be superior to 6 and 10 °C temperatures for breaking seed rest in all species, as was 120-day after-ripening when compared with 30-, 60-, and 90-day periods. Scarification (a) by mechanical seed coat abrasion was harmful to germination; (b) with saturated NaOH solution for 20 minutes had no effect on germination; and (c) with concentrated H2SO4 for 10 to 20 minutes, depending on the species under test, was highly beneficial to germination. Chromatographic partition and bioassays of extracts from resting Amelanchier and Sorbus seeds revealed the presence of unidentified growth inhibitors and these are presumed to be primary reasons for prolonged seed rest.