Effect of Air-Borne Salinity on the Growth and Appearance of the Tropical Perennial Strandline Plant, Commelina erecta subsp. maritima (C.V. Morton) C.V. Morton

Selection of salt spray tolerant plants with good physical appearance is of concern to ornamental growers in coastal communities. Commelina erecta subsp. maritima (C.V. Morton) C.V. Morton is a seashore plant that is widely distributed along the coast of West Africa. Therefore, the effect of salt spray was examined on the plant in a greenhouse experiment to determine its responses to various levels of air-borne salinity and to have an insight in the ecophysiological adaptations underlying these responses. It was also aimed to determine if varying levels of salt spray differentially damaged the plant. Filtered seawater was used to spray potted plants at: two sprays per week (2SS), four sprays per week (4SS) or six sprays per week (6SS) while in the control treatment (CSS), plants were sprayed with deionized water. Plants sprayed with seawater did not differ significantly (p > 0.05) in percentage necrotic leaf area compared to the control. All the plants survived but growth was inhibited by salt spray. Salt spray caused a significant (p < 0.05) reduction in leaf size and total chlorophyll content. Salt was accumulated in the shoot of salt-sprayed plants which led to ion toxicity. Salt sprays led to reduction in amount of essential nutrients in plant parts. C. erecta subsp. maritima adjusted osmotically to salt stress and increased stem succulence for ion dilution. The growth of the plant was negatively affected by salt sprays but it showed no significant necrotic damage, hence it is suitable for use as a landscaping plant in coastal beaches.