Propagation of the northern Gulf of Mexico coastal dune endemic Crocanthemum arenicola (coastalsand frostweed)

Abstract

Coastalsand frostweed (Crocanthemum arenicola (Chapm.) Barnhart [Cistaceae]) is a back dune plant of the north central Gulf of Mexico endemic to coastal Florida, Alabama, and Mississippi. We initiated seed and cutting propagation experiments to test the effects of scarification, photoperiod, and temperature on germination of C. arenicola. In addition, we examined the effects of cutting maturity (vegetative or reproductive stems), auxin (IBA) concentration, and time of rooting on the percentage of cuttings with roots and the quality of rooted cuttings of C. arenicola. We conducted 3 single-factor experiments in which seeds were subjected to scarification treatments, photoperiod treatments, or a gradient of temperature treatments, and germination (radicle emergence) was monitored over time (2–4 wk). A two-factor greenhouse cutting experiment was conducted comparing cutting maturity and auxin concentration on root number and root length of C. arenicola 3 and 7 wk after sticking. We assessed cuttings for root class at 7 wk. Scarification by sandpaper abrasion (50–200 s) increased germination compared to a non-scarified control (≥90% compared to 11% germination). Photoperiod had no effect on germination, with similar germination in the light and dark. Higher germination occurred under cooler temperatures than warmer temperatures. Rooting at 3 wk (51%) was lower compared to rooting at 7 wk (76%). More roots were present on vegetative cuttings compared to reproductive cuttings (4.2 compared to 2.7 roots per cutting). Root length and root class did not differ with the application of auxin.