This work is a comparative study of photosynthetic gas exchange and respiration of isolated chloroplasts and leaf discs of halophytes plant leaf (Atriplex halimus L.). Plants are stressed by salted solution at 400 meq.l-1 and 600 meq.l-1 NaCl+CaCl2 Haogland nutrient solution and seawater diluted (50%) and undiluted. Gas exchange were measured during 30 min through the oxygen released during photosynthesis in the reaction conditions of illumination and oxygen absorbed during respiration in dark conditions by using the device WARBURG. The results obtained show that the salinity of sea water or NaCl+CaCl2 affects the respiratory and photosynthetic activities. These activities, however, vary depending on the concentration of the medium, the nature of stress. Indeed, the gas exchange of leaf chloroplasts of plants of Atriplex halimus L., shows a decrease in the absorption of oxygen concentration at 400 meq.l-1 NaCl+CaCl2; watering with sea water without dilution causes a slowing of the respiratory activity of chloroplasts of Atriplex halimus L. The photosynthetic activity of leaf chloroplasts of plants is more intense and favored under stress at 400 meq.l-1 NaCl+CaCl2.
Keywords: photosynthesis, respiration, chloroplasts, salinity, halophyte