Response of Populus × canescens (Populus tremula × alba) to high concentration of NaCl stress

Abstract

Populux × canescens was cultivated on solid substrate and treated by salt (150 mM NaCl). The growth parameters including new leaf formation, height increment, diameter at the base increment, fresh and dry mass of leaf, stem, coarse root, and fine root were determined. The nutrient elements in leaves of samples under salt stress and the control, and the chlorophyll fluorescence of plants separated dark and light, initial fluorescence (Fo), and maximum fluorescence (Fm) were measured. Results showed that 150 mM NaCl treatment resulted in growth reduction of Populus × canescens. Nutrient element contents in the foliage of plants under salt stress were different from that of control. The foliar N-concentrations of plants under salt stress were not affected. Contents of Na under salt stress were 120 times as much as that under control. However, contents of S, K, P, Ca, Mg, Fe, Mn under salt stress were less than that under control. Salt stress caused damage in the PSII reaction centers, i.e. photo-inhibition couldn’t be repaired under dark situation. The yield of chlorophyll fluorescence showed that several parameters associated with PSII functions, e.g. Fv/Fo, Fv/Fm were not influenced at the first stage of salt stress treatment. However, after a period of time, PSII functions were significantly inhibited, which led to the decrease of carbon assimilation. These results suggest that salt stress (150 mM NaCl) did not affect photosynthetic chlorophyll fluorescence of Populus × canescens immediately. After four day of salt stress, PSII reaction centres were seriously damaged during photo-inhibition.