Benzoic acid (BA) and Cd exhibit cumulative effects on plants due to their accumulation in the soil. The present study reports the effects of BA an allelochemical, Cd and their combinations on seed germination, seedling growth, biochemical parameters, and response of antioxidant enzymes in Triticum aestivum L. The experiment was conducted in sand supplemented with Hoagland nutrient solution. Benzoic acid was applied at concentrations of 0.5, 1.0, and 1.5 mM with or without Cd (7 mg L -1 ) to observe effects of allelochemical and Cd alone and in combination on wheat. Both stresses exhibited inhibitory effect on growth and metabolism of wheat seedlings. The allelochemical in single and combined treatments with Cd decreased seedling growth as compared to Cd stress. The two stresses significantly enhanced malondialdehyde content of wheat seedlings. The activity of other antioxidant enzymes, viz. superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and guaiacol peroxidase (POX) were also recorded. SOD increased in seedlings under the two stresses. CAT more prominently ameliorates the toxic effects of H2O2 as compared with APX and POX and protected wheat seedlings from oxidative stress. Allelochemical buttressed the toxic effect of Cd on wheat seedlings.

The present work examines benzoic acid (BA) induced stress in Solanum lycopersicum and explores the possible mechanism through which sodium nitroprusside (SNP) protects plants. Tomato seeds were soaked for 3 h in 250 mM SNP and 0.5, 1.0, and 1.5 mM BA with and without SNP. Seeds soaked in distilled water were treated as control. Seed germination (SG) and radicle length (RL) were recorded in Petri plate culture. SG and RL inhibition was concentration dependent in BA. SNP enhanced SG and RL. Twenty-one-days old seedlings were grown in hydroponic culture in Hoagland solution and BA at 0.5, 1.0, and 1.5 mM with and without SNP. The morphological and biochemical parameters of seedlings were assayed. Average growth rate of root and shoot, dry weight, sugar, pigment and protein content, and activity of nitrate reductase decreased in seedlings treated with BA while increased in SNP with and without BA. Lipid peroxidation increased in seedlings treated with BA but decreased in BA 'SNP. SNP protected the seedlings against BA induced oxidative stress by scavenging reactive oxygen species. SNP demonstrated a positive role against BA toxicity which was evident from increased activities of antioxidant enzymes.

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