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Assessment of salt tolerance in Eucalyptus, Rain tree and Thai neem under laboratory and the field conditions

Suriyan Cha-um^* and Chalermpol Kirdmanee

Abstract: The aim of this investigation was to discover an effective index for salt-tolerant selection in plant tissue culture system and to assay the physiological responses in a salinity field trial. Net-photosynthetic rate (NPR) in salt-tolerant clones of Eucalyptus (Eucalyptus camaldulensis Dehnh.), Rain tree (Samanea saman Merr.) and Thai neem (Azadirachta siamensis Val.) was gradually reduced when exposed to 0.17, 0.34, 0.68 or 1.02 M NaCl salts contained in the culture media, while that in salt-sensitive clones was sharply decreased. The reduction percentage of NPR in salt-tolerant species grown under salt stress was lower than that in salt-sensitive species by a factor of 2-3 folds. The NPR reduction in plant species grown under salt-stress was evidently investigated as effective index for salt-tolerance. In addition, physiological characteristics, chlorophyll content and maximum quantum yield of PSII (F_v/F_m), in salt-tolerant clones were significantly adapted to salinity field trial at Mahasarakham province, Northeastern region of Thailand, leading to high survival percentage and grew well when compared to the salt-sensitive clones. The salt-tolerant clones of forest tree species can be further used for salinity phytoremediation and ecological succession.

National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), 113 Thailand Science Park, Paholyothin Road, Klong Luang, Pathumthani 12120, Thailand.