Influence of Storage Temperatures on Long-term Seed Viability of Selected Native Ericaceous Species

Abstract

Abstract Following harvest of capsules, drying, and seed extraction, seeds of Kalmia latifolia L. (mountain laurel), Leucothoe fontanesiana (Steud.) Sleum (drooping leucothoe), Rhododendron carolinianum Rehd. (Carolina rhododendron), Rhododendron catawbiense Michx. (Catawba rhododendron), and Rhododendron maximum L. (rosebay rhododendron) were stored for 0, 1, 2, 3, 4 or 5 years at −18,4 or 23C (0, 39 or 73F) and then germinated at 25C (77F) or an 8/16 hr thermoperiod of 25/15C (77/59F) with daily photoperiods of 0, 1 or 24 hr. Storage at −18 or 4C (0 or 39F) were most effective for maintaining seed viability of all species. After 5 years storage at −18 or 4C (0 or 39F), viability of L. fontanesiana, R. catawbiense, and R. maximum was relatively unchanged with total germination of 59%, 87%, and 88%, respectively. The same was noted for seeds of K. latifolia and R. carolinianum with total germination of 77% and 91%, respectively, after storage for 4 years at the same temperatures. Storage at 23C (73F) was the least effective for maintaining viability. After storage for 1 year at 23C (73F), germination decreased significantly for all species except R. carolinianum. By year 3, storage at 23C (73F) reduced seed viability of L. fontanesiana to essentially zero. The same occurred by year 4 for seeds of R. catawbiense and R. maximum stored at 23C (73F). Viability of K. latifolia also decreased under storage at 23C (73F) with germination of 14% noted by year 4. Viability of R. carolinianum did not decrease as rapidly as the other species when stored at 23C (73F) with total germination of 77% occurring by year 4. Regardless of storage duration, the photoperiod and temperature requirements for maximum germination of all species did not change.