ALLEVIATION OF THE SALINITY EFFECTS ON THE GROWTH AND DEVELOPMENT OF Populus nigra BY EXOGENOUS APPLICATION OF SILICON AND GLYCINE BETAINE

Populus nigra plants were subjected to four soil salinity levels (0. 0,3.0, 5.0 and 7.0 dSm) in a pot experiment with two types of nutrients foliar applications (silicon at 100 and 200 mg/l and glycine betaine at 200 and 400 mg/l). Salinity treatments reduced all growth characters. On the other hand, sugars, proline, Na and Cl contents increased by increasing salinity levels, while chlorophylls, N, P and K diminished. Foliar application of silicon or glycine betaine enhanced all the studied growth characters, as well as the organic (sugars, proline and chlorophylls) and inorganic components (N,P and K), while Na and Cl decreased. The combination of Si (200 mg/l) + GB (400 mg /l), gave the best results, alleviating the adverse salinity effects on the growth and development of Populus nigra.