With regard to researches of other authors and in the continuation of our preceding studies. Dunaliella viridis (a green alga) was collected from salt works adjacent to the Urime lake (a hyper saline one), in the soul west of Iran, and the effects of salt (common salt) stress on pigments, proteins and glycerol and finally on the ultras tructure were scrutinized. The results have been summarized as follows.
1- The effect of light growth:
The effect of light intensity (1000-8000 lux) on the growth of the alga in two salt treatments (250%, & 300%), each with three replica as, was inspected. Generally, there was a linear relationship between light intensity and growth. In a given light intensity, the average of algal growth in 300%, in some cases, reached to fewer than the half of the average of growth in 250%, increasing of light intensity could not reduce the effect of salinity on growth Probably, involving of photo inhibition, there was no alga in 8000 lux treatment. The optimum light intensity was 3000-6000 lux.
2- The effect of temperature on growth:
The effect of three temperatures, 25±2.35±2 &42±2C, on algal growth, in 250%, and 300%., was studied. In general, as temperature was increasing, the growth was increasing too. The increment of the growth, as the temperature rising, in 300%, was much more than 250%. It is appeared that, higher temperature reduces the effect of salinity on the growth in other words, the resistance to higher salinity becomes more. The optimum temperature was 35 C.
3- the effect of salinity on growth:
The effect of Salt on growth (cell numbering) in non, salt, 50%., 100%., 150%., 200%., 250%., 300%., 350% & 400% were studied. By reason of extreme turgor and thus, the cell bursting, there was no cell in 0%. As salt concentration was increasing, the alga growth reduced. In addition, in the lower salt concentrations, the maximum growth was obtained in shorter time. The optimum salt concentration for growth was 250%., 300%.
4- The effect of salinity on pigments, protein & glycerol contents:
The effect of salinity on pigments, protein and glycerol contents in four treatments, 150%., 200%., 250%., & 300% was studied. As salt concentrations was increasing, the chlorophyll content was decreasing, white protein and glycerol were raising. Comparing protein profiles of the aboved mentioned treatments, showed increasing and / or decreasing or even presence or absence of some protein bands.
5- The effect of salinity ultra structure:
in four salt treatments, 150%., %200., %250. & 300%. The fine structure of the alga was scaned. The electron microscopy examination did not emerge differences.
Unlike higher plants, which show clear morphological changes in presence of salt, it is appeared that salt stress with inducing main biochemical changes in Dunaiieiis, while adjusting cell osmosis and recovering the original volume of the cell, exerting no obvious changes morphologically.