Influence of Sea Sprays on Growth and Visual Quality of Seashore Paspalum (<i>Paspalum vaginatum</i> O. Swartz) use in Beach Landscaping

Abstract

Growth and visual quality of Paspalum vaginatum O. Swartz were examined, to determine its responses to various levels of air-borne salinity and to have an insight in the ecophysiological adaptations underlying the responses. Potted plants were sprayed with air-borne seawater at: two sprays per week (2SS), four sprays per week (4SS) or six sprays per week (6SS), which equaled on average 4, 8 and 12 mg NaCl dm -2 leaf area day -1 respectively. The control (CSS) plants were sprayed with deionized water. Plants responded to sea spray by leaf folding and no mortality occurred. Except stem girth that increased, growth parameters decreased with increasing seawater application level, but leaf width, root number and root length were not affected. It significantly decreased fresh and dry mass of aerial parts, total biomass and leaf total chlorophyll. It also induced leaf and stem succulence and decreased plant xylem water potential. It caused nutrient imbalance by accumulating Na + and Cl - ions but lowered Ca 2+, Mg 2+ , K + and Fe 2+ in the aerial parts. Na: K ratio and N were significantly higher in leaf and stem of salt-treated plants than in control. It increased total nutrient and percentage ash, contributed mainly by Na + and Cl - ions, but decreased organic content in leaf and stem. Generally, roots were not affected by salt spray. Air-borne salt significantly increased necrotic leaf area but did not significantly affect plant visual ratings. The implications of the results on the growth and use of seashore paspalum for beach landscaping are discussed.