Changes of growth and cell size of Salsola arbuscula callus

Salinity is an environmental stress and is the main limiting factor in the efficiency of agriculture products in the world. Salsola arbuscula is a halophyte plant and resistant to high salinity, therefore, this investigation was aimed to study the tolerance mechanisms to salt stress with the changes in growth parameters and microscopic study of callus. To achieve our purpose, firstly, seeds were cultured in the MS medium and after 2months; callus was produced from root explants in the different media. Calli were then transferred to the previous culture medium with different concentrations of NaCl salt (0, 100, 200, 300, 400 mM) and after one month, fresh and dry weight, relative growth rate (RGR), relative water content (RWC), sensitivity index (SI) and cell dimensions were measured. Results showed that the best medium to induce callus production were medium of MS with 2,4D (1mg/L) + Kin(1mg/L). With increasing of NaCl concentration, callus color changed and necrosis occurred higher and faster. Also with increasing NaCl concentration fresh and dry weight, relative growth rate, relative water content and sensitivity index were decreased and fresh weight decreased more than dry weight. length, width, and area of the cells decreased as the stress was increased. Salt effect on cells length was higher than width by decreasing of the size and the growth of the cells.