Germination of Grass Seeds After 8 Years of Weekly Removal from Subfreezing Storage 1

The use of subfreezing storage temperatures has increased in recent years for many kinds of seeds. However, the literature contains no information on the effect on seed viability when grass seeds are frequently removed from subfreezing storage for sampling purposes. Seeds of six grass cultivars produced at Prosser, WA, in 1976 were divided into five sublots for a long‐term storage study. The study included two cultivars each of orchardgrass ( Dactylis glomerata L.) and red fescue ( Festuca ruba L.) and one each of chewings fescue ( Festuca ruba var. commutata Gaud.) and Kentucky bluegrass ( Poo pratensis L.) The storage conditions were (A) cotton bags in an unheated warehouse, (B) vacuum‐sealed cans stored in an unheated warehouse, (C) continuous frozen storage (D) frozen storage but thawed one day each month, (E) frozen storage but thawed 1 day each week. Seed moisture content before storage was 8% ± 0.4%. Germination tests were conducted prior to storage and once each year thereafter. A freezer set at −10°C and near 60% relative humidity was used for the subfreezing storage. The original and 8th year germination results of sublots from storage treatment (E) were ‘Latar’ orchardgrass, 90 and 84%; ‘Pennlate’ orchardgrass, 91 and 87%; ‘Dawson’ red fescue, 83 and 83%; ‘Erika’ red fescue,87 and 86%; ‘Barfalla’ chewings fescue, 80 and 76%; and ‘Baron’ bluegrass, 93 and 88%, respectively. Germination losses for sublots from storage treatment (A) ranged from 19 to 53%. Results indicate germination percentages of grasses can be maintained at, or near original levels for at least 8 years when seed is either continuously frozen or frozen and thawed weekly for 24 h and returned to subfreezing storage but declines significantly when stored in an unheated warehouse.