Effect of Silicon on the Biochemical and Physiological Attributes of Wheat Under Fluoride Stress

The purpose of the current study was to evaluate the alleviating effect of silicon (Si) on fluoride (F)-mediated toxicity in wheat cultivars.The photosynthetic efficiency of fully developed wheat leaves was measured by analysing the chlorophyll fluorescence using DUAL-PAM (Heinz Walz, Effeltrich, Germany). The quantitative changes in various biochemical parameters, viz. photosynthetic pigments (chlorophylls and carotenoids), proline, flavonoids, polyphenols, hydrogen peroxide (H2O2) glutamate and ascorbate content in wheat leaves, were monitored by UV-VIS spectrophotometer using established methods. To describe the magnitude of the relationships among biochemical and physiological parameters, the Pearson correlation coefficient was calculated.Our results showed that F stress (400 and 500 mg/kg) affected various photosynthetic parameters (i.e. ETRmax, PPFDsat, 1/2PPFDsat, Delta F/Fm ' sat and 1/2 Delta F/Fm ' sat) and reduced the amount of photosynthetic pigments. Further, increased proline, flavonoids, polyphenols, H2O2, glutamate and ascorbate content in F-stressed wheat plants showed fluoride-induced oxidative damage. In contrast, application of 200 and 300 mg/kg Si to F-toxic soil restored the Chl pigment and photosynthetic parameters and reduced F-induced oxidative damage by concomitant decline in proline, flavonoids, polyphenols, H2O2, glutamate and ascorbate content.By understanding the positive role of Si in plants with and without F stress, the current study has concluded that Si contributed to increased resistance to F stress in wheat cultivars by increased antioxidant metabolites and thereby reduced oxidative damage.