Fathi and Asem (2013) while working with Chlorella, also reported that high salinity (50 gL-1) leads to
decrease in β-carotene content. Pisal and Lele (2005) on the basis of their experiments on unicellular green
alga Dunaliella salina suggested that the cells show unbalanced physiological conditions under the
influence of various stresses leading to increased β–carotene content.They observed increased production
of β-carotene in cells with increasing NaCl in the growth medium. They suggested that, β-carotene is a
secondary metabolite and these molecules are produced by the cells under stress for protection They
observed that 3 M NaCl concentration was the optimum for carotenoid production. Rad et al. (2011) while
studying the effect of salinity on cell growth and β-carotene production in a unicellular microalga Dunaliella
reported increased β-carotene content with increase in the salinity of the culture medium.while studying the relationship between endogenous abscisic acid and β-carotene synthesis in
different species of Dunaliella, observed that at 3.5 M NaCl concentration, β-carotene accumulated in salt
stressed cells of Dunaliella salina after a decrease at initial hours of stress, as compared to control (1.5 M
NaCl). In contrast, they have reported no noticeable change in β-carotene production in Dunaliella viridis
under similar experimental conditions.