Abstract
The present study was carried out to investigate biochemical responses of marigold (Calendula officinalis L.) to Bio-organic fertilizers. Effects of co-inoculation of two plant growth-promoting rhizobacteria (PGPR) (Azotobacter sp.145PI and Azospirillum sp.AC49I), humic acid (HA) (10 kg ha−1), vermicompost (VC) (7 T ha−1) and combinations of these treatments were evaluated in two marigold cultivars [Isfahan double flower (DF) and single flower (SF)]. The biosynthesis of leaf protein, soluble and insoluble carbohydrate contents were increased in treated plants, while total free amino acid content was not influenced by treatments. Fertilizers also had positive impact on leaf and flower pigments, total flavonoid content, and total phenolic contents. Maximum amounts of anthocyanins were obtained in the DF cultivar treated by VC+PGPR and VC, which were 11.414 and 11.192 µmol g-1 FW, respectively. The SF cultivar treated by PGPR (36.11 %) and also the same cultivar treated by VC (33.39 %) had the highest antioxidant activities. In general, simultaneous application of fertilizers and also vermicompost were recognized as the best treatment for marigold plants. In conclusion, the findings of the current study confirmed that chemical composition and antioxidant activity of marigold can be positively influenced by Bio-organic fertilizers; therefore they can be used to obtain medicinal plants with improved quality during sustainable agricultural practices.
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