Evaluating the Ornamental Potentials of Four Native Texas Coastal Species
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With increasing demand for high quality irrigation water and coastal development, new plants need to be developed that thrive with the use of saline irrigation and provide an alternative to invasive exotic landscape plants. Accessions of Erigeron procumbens (Houst. ex Mill.) G.L. Nesom, Borrichia frutescens (L.) DC., Sesuvium portulacastrum (L.) L., and Oenothera drummondii Hook. were collected along the Texas coast from Port Isabel to Port Arthur. Then taxa were screened for phenotypic variability, responses to plant growth regulators, and tolerances to saline irrigation water. Phenotypic variability appeared most promising in O. drummondii and B. frutescens for future breeding efforts. There were differences among accessions for all four species and there were regional differences in flowering and height for B. frutescens and O. drummondii. For B. frutescens height was reduced 54.9% by paclobutrazol at 40 mg a.i.∙pot^-1 and 34.9% by uniconazole at 2 mg a.i.∙pot^-1 when applied as a drench. Height and plant growth in O. drummondii was controlled with paclobutrazol drenches of 30 mg a.i.∙pot^-1 and uniconazole drenches of 1.5 mg a.i.∙pot^-1. Similar results were found in E. procumbens and S. portulacastrum, with spray applications of PGRs being generally ineffective on all four taxa. All four taxa were irrigated with four concentrations of saline water, with electrical conductivities (EC) of 0.8, 15.1, 23.8, 51.3, and 92.5 mS∙cm^-1, either applied sub-canopy or over the foliage. Concentrations above the control roughly represented the salinity of quarter, half, full, and double the salinity of seawater, respectively. All four species survived irrigation water with an EC of 23.8 mS∙cm^-1 and showed minimal damage with 15.1 mS∙cm^-1. Growth responses, mineral nutrient content, and K/Na ratios were consistent with reports of the halophytic nature of S. portulacastrum, which tolerated the greatest salinity exposure. Due to commercial interest, mating system and pollen storage studies were carried out on O. drummondii. In mating system experiments, out crossed flowers had a mean seed count of 240.5 (± 17.5) seed∙fruit^-1 and selfed flowers across all dates and treatments had a mean seed count of 285.0 (± 14.1) seeds∙fruit^-1 after 10 d on filter paper. This indicates a facultative out-crossing species and emasculation of flowers is not necessary in pollinator excluded environments.
Carver, Sean Thomas (2015). Evaluating the Ornamental Potentials of Four Native Texas Coastal Species. Doctoral dissertation, Texas A & M University. Available electronically from