Comparison of the effect of silicon and nano-silicon on some biochemical and photosynthetic traits of Zea mays L. under salinity stress

Salinity stress is one of the factors that threatens the growth and yield of corn. The effects of silicon or nanosilicon on salinity alleviation have been reported in some plants. The effects of foliar application of silicon (inorganic and nanopatricle) on mitigation of the effects of salinity stress on some photosynthetic and biochemical parameters were studied in corn. Experiments were conducted in a completely randomized design with factorial arrangement in a pot culture. The first factor was salinity at two levels including 0 and 100 mM NaCl and the second factor was silicon at three levels including control (without silicon) and 2 mM potassium silicate and 2 mM nanosilicon (SiO2). Under salinity stress, the fresh and dry weights of shoots and roots, the chlorophylls and carotenoids contents, and the amount of soluble protein decreased significantly compared to the control. In contrast, the amount of hydrogen peroxide and malondialdehyde increased in these plants. Also, the photosyntheic rate and water use efficiency of plants decreased under salinity. The application of silicon and nanosilicon improved the growth of plants under salinity and increased the photosynthetic rate and the amount of photosynthetic pigments. In addition, severe reduction in transpiration under silicon application compared to nanosilicon resulted in the increased water use efficiency in this treatment. Silicon application also increased the activity of soluble peroxidase enzyme in plants under salinity, a result which was not observed with nanosilicon application. This resulted in a further decrease in hydrogen peroxide and lipid peroxidation of plants under salinity treated with silicon compared to nanosilicon, which showed a further decrease in oxidative stress in this treatment. These findings indicated that stress reduction and growth improvement of the plants under salinity with silicon application were more than the treatment with nanosilicon.