Abstract
Barium, known to be a toxic element to plants, can adversely affect the photosynthesis and growth of plants at high doses but its effects at low doses on the growth and productivity of wheat are unknown. To this end, a soil culture experiment was conducted to study the effect of five Ba levels on the growth attributes, dry matter production, biochemical constituents, and antioxidant enzymes of wheat. Plants were grown in the soil containing various concentrations (0.1, 1, 10, 100, and 1000 µg g(-1)) of Ba in the form of barium chloride dihydrate. The growth parameters, biochemical constituents, antioxidative enzymes, and seed production were assessed. Ba showed promotory effect on the growth attributes of wheat at lower applied concentrations (< 10 µg g(-1)). However, higher doses of Ba (≥ 100 µg g(-1)) were toxic to wheat and resulted in reduced root length (-33.34%), leaf area (-70.32%), root dry weight (-54.44%), and seed weight (-41.16%). The changes in biochemical constituents were correlated with soil Ba concentrations. Chlorophyll contents increased under lower concentrations of Ba (0.1-10 µg g(-1)) applied. At 10 µg g(-1) Ba, leaf area (83.18%), root fresh weight (78.21%), chlorophyll b (71.58%), chlorophyll a (53.17%), total chlorophyll (53.45%) and seed weight (13.6%) increased. Ba concentrations beyond 10 µg g(-1) significantly increased total phenolic compounds, free proline contents, and soluble proteins. The activity of peroxidase and catalase was decreased at lower concentrations (up to 10 µg g(-1)) and beyond this level, the activity of these enzymes increased. The lower application of Ba (up to 10 µg g(-1)) has beneficial effect on wheat. The activities of antioxidative enzymes stimulated in wheat highlighted the occurrence of oxidative damage under high Ba treatments. Among the different Ba concentrations investigated, up to 10 µg g(-1) of Ba was beneficial for wheat, 100 µg g(-1) was only moderately toxic, and 1000 µg g(-1) was highly toxic. Our findings indicate that low concentrations of barium can effectively enhance wheat production and can contribute to food security after confirming the level of translocation in the food chain.