Sexual and Asexual Propagation of Wild Lime (Zanthoxylum fagara L. Sarg.), a Native Florida Plant with Ornamental and Ecological Value

Abstract

Abstract A series of four propagation studies were implemented to better understand the seed biology of wild lime (Zanthoxylum fagara L. Sarg. [Rutaceae]) and its adventitious rooting response to auxin treatments. Plant origin (north central vs south Florida ecotypes) did not affect initial seed viability but significantly influenced germination response to seasonal temperatures. Fifty-five days after sowing north central Florida seeds, germination was similar among spring, summer and fall treatments (28.9 to 41.1%), but was reduced by the winter temperature (10.7%). South Florida seeds showed greatest germination under the fall temperature (71.2%), and the least germination under the summer temperature (30.2%). Additional seed treatments including applications of gibberellic acid (GA3) with kinetin nominally improved germination by 1.2 times compared to non-treated seed. Seeds tolerated cryopreservation treatments, including combinations of a plant vitrification solution, liquid nitrogen, phloroglucinol and precooling, suggesting long-term storage capability. As an alternative to seed propagation, cutting propagation was found to be a reliable means of reproducing wild lime with 91.0% rooting success when softwood cuttings were treated with 8,000 mg·kg−1 (0.13 oz·lb−1) indole-butyric acid (IBA), compared to 3,000 mg·kg−1 (0.05 oz·lb−1) IBA (86.3%) or the non-treated control (71.2%). Species used in this study: Wild lime, Zanthoxylum fagara (L. Sarg). Chemicals used in this study: 2,3,5-triphenyl-2H-tetrazolium chloride (TZ); sodium hypochlorite solution (Clorox bleach); gibberellic acid (GA3); kinetin (kinetin), plant vitrification solution 2 (PVS2); liquid nitrogen (LN); phloroglucinol (phloroglucinol); glycerol (glycerol); dimethyl sulfoxide (DMSO); MS media (Murashige and Skoog media), sucrose (sucrose); 15N-5P-15K liquid fertilizer (Peters Excel Cal-Mag Special); indole-3-butyric acid (IBA); 14N-14P-14K slow-release fertilizer (Osmocote).