Visual Quality and Morphological Responses of Rosemary Plants to UV-B Radiation and Salinity Stress

In order to understand the effects of ultraviolet-B (UV-B) radiation and salinity stress on the visual quality and morphological parameters, one-year-old seedlings of rosemary (Rosmarinus officinalis L.) were grown under three UV-B levels (0, 4.32, 6.05 kJ m(-2) d(-1)) and four salinity regimes (Control, 50, 100 and 150 mM NaCl) under greenhouse conditions. The results showed that enhanced UV-B radiation increased visual quality, growth index, plant biomass, shoot/root ratio, number of branches and leaves, leaf fresh and dry weight, leaf area index, specific leaf area, leaf thickness. The UV-B radiation had no significant effect on root length; however, shoot height, length of axillary shoots, length of inter node, leaf area, leaf length and width and concentration of chlorophyll b were negatively impacted by the UV-B radiation. On the other hand, salinity caused a significant decrease in plant biomass, root length, shoot height, shoot/root ratio, length of axillary shoots, length of inter node, number of branches and leaf area, leaf area index, leaf length and width, leaf fresh and dry weight, specific leaf area and concentration of Photosynthetic pigments. However, the number leaves and leaf thickness significantly increased under NaCl salinity treatments. Visual quality and growth index were hardly affected by increasing salinity until 100 mM, but declined clearly at 150 mM NaCl salinity. The interaction between UV-B irradiation and salinity showed that pre-treatment with UV-B irradiation alleviated the harmful effects of NaCl and improved the visual quality rosemary plants.