Influence of Light and Temperature on Seed Germination of Flame Azalea
Seeds of flame azalea [Rhododendron calendulaceum (Michx.) Torr.] were germinated at 25°C (77°F) and 25°/15°C (77°/59°F) with daily photoperiods of 0, ½, ½ twice daily, 1, 2, 4, 8, 12 and 24 hr. Seeds exhibited an obligate light requirement. At 25°C (77°F), increasing photoperiods increased germination with maximum germination (85%) occurring by day 12 under continuous illumination. The alternating temperature of 25°/15°C (77°/59°F) enhanced germination when light was limiting. At this temperature, maximum germination of 84 to 91% was reached by day 24 for all photoperiods ≥½ hr although at photoperiods ≥4 hr, comparable germination was noted at day 18.Abstract
Contributor Notes
Paper No. 12017 of the Journal Series of the North Carolina Agricultural Research Service (NCARS), Raleigh, NC 27695-7643. Assistance of the staff of the Southeastern Plant Environment Laboratory (Phytotron) is gratefully acknowledged.
2Graduate student. This paper is based on a portion of a thesis to be submitted by the senior author in partial fulfillment of the requirements for the Ph.D. degree.
3Professor.
4Assistant Professor.
5Associate Professor, Department of Soil Science.