<p>The detrimental effects of salinity are more devastating during early reproductive stages and potential of seed pre-treatments in alleviation of such effects and metabolic adaptation of wheat to booting stage salinity remains elusive. The present pot study investigated the regulatory effects of thiourea (TU) seed pre-treatments (0.1,&#xa0;0.2,&#xa0;0.3&#xa0;and 0.4 mM) on the growth, flag leaf photosynthetic pigments, secondary metabolites and ionic contents in root and shoot of wheat plant (cv. Fsd-2008) measured at anthesis 20&#xa0;days after salinity stress (120 mM) given at booting stage. The water-soaked and dry seed controls were taken as controls. Salinity reduced the height, leaf area and dry matter per plant, flag leaf Chl&#xa0;a,&#xa0;b, carotenoid contents, and inorganic K⁺, Ca²⁺, K⁺/Na⁺, Ca²⁺/Na⁺ including nitrate, phosphate and sulphate contents in root and shoot of wheat compared to normal. Salinity increased the accumulation of Na⁺ (16%, 13.7%), flavonoids (27%, 23%) and anthocyanins (28.2%, 21.3%), total phenolics (22.5%, 19.7%) and soluble sugars (22.2%, 19.4%) in root and shoot while MDA (8.4%) and H₂O₂ (20%) in shoot only of wheat plant. Seed pre-treatment with 0.3&#xa0;or 0.4 mM TU improved the growth, flag leaf Chl a&#xa0;contents (15%, 17.8%), increased secondary metabolites and nutritional status at anthesis stage in wheat under salinity. Seed pre-treatment with 0.4 mM TU also reduced the shoot MDA (6.7%, 9%) and H₂O₂ levels (20.8%, 12.2%) under both normal and saline conditions. In crux, seed pre-treatment with 0.4 mM TU successfully improved the adaptation of wheat plants to salinity owing to increased accumulation of secondary metabolites, inorganic ions and essential nutrients with simultaneous decrease in oxidative stress and ionic toxicity in shoot of wheat plant at anthesis stage.</p>