The effect of biological fertilizers on some quantitative and qualitative characteristics of calendula (Calendula officinalis L.)

The use of biological fertilizers and balanced plant nutrition as the most important soil fertility factors are among the main priorities of sustainable agriculture. In order to investigate the effect of biological fertilizers on some quantitative and qualitative characteristics of Calendula officinalis L., an experiment was done in the form of a completely randomized design with 14 treatments including (Azotobacter, Azospirillum, Pseudomonas, Thiobacillus, Azotobacter + Azospirillum, Azotobacter + Pseudomonas, Azospirillum + Thiobacillus, Azospirillum + Pseudomonas, Azotobacter + Azospirillum + Thiobacillus, Azotobacter + Pseudomonas + Thiobacillus, Azotobacter + Azospirillum + Pseudomonas, Azotobacter + Azospirillum + Pseudomonas + Thiobacillus, Pseudomonas, Thiobacillus, Thiobacillus + Azotobacter) and three replicates in the greenhouse of Nahavand Higher Education Complex in 1402. The results showed that the highest amount of phenol (1.86 mg GAE/gr) and flavonoid (5.54 mg routine/gr) was obtained in the combined treatment of Thiobacillus and Azotobacter. The highest stem diameter (17.48 mm) was produced in the combined treatment of Azotobacter and Pseudomonas. The highest diameter (15.19 mm) was created in Pseudomonas treatment. The highest height of the plant (28 cm) was produced with the use of Azotobacter biological fertilizer. The highest number of sub-branches, number of flowers per plant, fresh and dry weight of flowers were created in Azospirillum and Pseudomonas treatments. Finally, it can be said that the use of biological fertilizers, in addition to improving the quantitative and qualitative characteristics of Calendula officinalis L., is also an effective solution for achieving the goals of sustainable agriculture.