The effect of silicon dioxide nanoparticles (SiO2) on chlorophyll content and chlorophyll fluorescence of five olive cultivars under salinity stress

Fluorescence parameters and chlorophyll content are the most important factors to determine the photosynthetic capacity during the life of plants. In this research, the effect of SiO2 nanoparticles was investigated on the characteristics of RWC, membrane stability, photosynthetic pigments and the functioning of photosystem II under sodium chloride salinity stress conditions in five olive cultivars. Two olive cultivars (Koroneiki and Conservalia as salinity-resistant and sensitive controls, respectively) and three selected genotypes (Deira, Kolahfaraj and Shiraz) at two levels of salinity (0 and 150 mM sodium chloride) and three levels of nanoparticles of SiO2 (0, 1 and 2 mM) were investigated. The results showed that in all investigated cultivars, membrane stability and relative water content decreased in sodium chloride salinity treated plants. On the other hand, the application of SiO2 nanoparticles increased the relative water content, membrane stability and the amount of photosynthetic pigment in both control and salinity conditions. Shiraz genotype is more tolerant to sodium chloride salinity due to its superiority in most traits related to salinity tolerance compared to other cultivars. The results showed that application of SiO2 nanoparticles increased photosynthetic pigments under salinity stress. In general, it can be concluded that salinity stress reduced the content of photosynthetic pigments, relative water content, membrane stability and also the performance of photosystem II, and SiO2 nanoparticles improved these traits. It seems that the application of SiO2 at a concentration of 2 mM reduces the destructive effects of sodium chloride salinity stress in the studied olive cultivars.