Effect of sodium selenate on photosynthetic efficiency, antioxidative defence system and micronutrients in maize (Zea mays)

Oxidative stress or formation of faulty proteins due to non-specific replacement of sulphur by selenium(Se)/mineral imbalance can be one of the reasons for Se phytotoxicity. Present investigation reports the effect of Se on photosynthetic efficiency, anti-oxidative status and micronutrients in maize. Selenate-Se application (1-32 mg kg(-1) soil) showed significant growth reduction after 30 days of sowing and all the plants died with concentration higher than 4 mg kg(-1) soil. Lower Se doses increased dry matter, chlorophyll, proline and activities of defence enzymes viz. peroxidase, catalase and superoxide dismutase and decreased malondialdehyde, glutathione and glutathione reductase activity as compared to control. All the parameters showed the reverse trend with Se treatment of 4 mg kg(-1) soil. Concentration of nutrients (K, P, S, Mn, Mg and Ca) in leaves decreased with application of increasing Se doses. Shoot and root weight decreased (8.5-31.9% and 12-24%, respectively) in response to varying Se doses and highest Se accumulation in these tissues was observed with Se @ 4 mg kg(-1) soil. The phyto-toxic effects of higher Se doses may be due to its prooxidant effects and disturbances in nutrients level.