drought tolerance in Acer velutinum Boiss. seedlings using morphophysiological analysis

A Acer velutinum Boiss. (Persian or velvet maple) is one of the industrial and important species of Hyrcanian (Caspian) forests with wide distribution. This species is rarely seen in the forests of other parts of the world and has only been reported from the forests of the Caucasus. Therefore the information about this species is very limited. This research aims to investigate the response of A. velutinum seedlings to drought stress as one of the consequences of climate change. Seedlings of velvet maple were analyzed in terms of height, basal diameter, leaf area (LA), specific leaf area (SLA), biomass, photosynthesis pigments, relative water content RWC), free proline, malondialdehyde (MDA), superoxide dismutase(SOD), and peroxidase(POD) activities to drought stress. One year old of Potted plants were exposed to four water supply regimes (100, 75, 50, and 25% field capacity (FC); performed as a control, mild, moderate, and severe water stress. The results showed that drought reduced all aspects of growth in the velvet maple. It negatively affected on growth and reduced plant height, stem diameter, biomass, and leaf area, but SLA significantly increased under moderate treatment. Drought stress reduced chlorophyll content, however, no significant difference was found for carotenoids. RWC reduced significantly just under severe drought stress. Proline and MDA content increased significantly when plants were exposed to moderate and severe drought stress. Drought stress induced POD and SOD activity under drought treatments, although the highest activities were measured under mild and moderate treatments. Our data demonstrate that A. velutinum seedlings have relative drought resistance. They used drought avoidance and tolerance mechanisms through changes in morpho-physiological characteristics. The results of this research briefly showed the mechanisms of drought tolerance in A. velutinum and will provide essential information for more research in the future.