The growth and biochemical responses of ornamental French marigold using of organic amendments in a gas condensate-contaminated soil

In order to study the effect of organic amendment application on the growth and biochemical characteristics of French marigold (Tagetes patula) in soil contaminated with different levels of gas condensate, a factorial experiment was conducted based on a completely randomized design with three replications. The experimental factors consisted of gas condensate at five levels of 0, 7,500, 15,000, 30,000 and 60,000 μL per kg of soil, and soil amendment including vermicompost (5%), biochar (2%), Activated carbon (1%), vermicompost+ activated carbon+ biochar and non-amendment treatments. The results of the analysis of variance showed that the main and interactive effects of gas condensate and soil amendments were significant on traits of fresh and dry weight of root and shoot, chlorophyll a and b and proline content (P < 0.01). At the highest level of contaminant, the application of activated carbon and vermicompost+ activated carbon+ biochar respectively caused 3.82 and 4.45-fold increase in shoot fresh weight, 3.76 and 4.4-fold increase in root fresh weight, 2.52 and 2.56-fold increase in chlorophyll a, and also decreased 30.66 and 39.5 percent of proline content compared to the non-amendment treatment at this level of contaminant. The results of this research indicated the effective and useful role of organic soil amendment, especially activated carbon and vermicompost+ activated carbon+ biochar in reducing the toxicity of gas condensate on French marigold.