Morpho-physiological response of garden roses to saline aerosol stress

In order to evaluate the suitability of two rose hybrids for landscaping and gardening in sea coastal areas, a research was carried out on plants grown in pot in open field, submitted to saline spray to simulate the marine aerosol, with or without a previous foliar application of antitranspirant. The effects of 4 aerosol treatments, no spray, 0 ppm (only water), 15,000 ppm and 30,000 ppm of sodium chloride in water solution, were evaluated on two Tea hybrids, ‘Bella di Todi^®’ and ‘Dorada^®’, with or without a pre-treatment with Vapor Gard (96% pinolene, at 200 g 100 L^‑1 of water). Plants were sprayed twice a week, while the antitranspirant was applied every 2 weeks. In control plants, ‘Bella di Todi^®’ formed longer branches and greater plant leaf area compared to ‘Dorada^®’. Aerosol treatments reduced the number and length of branches and the plant leaf area in both the hybrids, also in plants sprayed with only water, with stronger effect at the highest salt concentration. In both the hybrids, the antitranspirant reduced the plant leaf area. Saline aerosol negatively affected the stomatal conductance, hence the net photosynthesis and transpiration rate, and reduced the plant water consumption, in both the hybrids. The number of flowers was higher in ‘Dorada^®’ compared to ‘Bella di Todi^®’ and in both the hybrids it was reduced by aerosol treatments, which had negative effects also on the overall plant ornamental value. As expected, antitranspirant determined a reduction in plant water uptake, while it was not effective in protecting plants by salt stress damages.