Bioactivation effects of spirulina microalga and humic acid on safflower (Carthamus tinctorius)

The Carthamus tinctorius, commonly known as safflower, is an annual plant with numerous branches and thorns from the Asteraceae family. For this experiment, three treatments were applied to the pots: humic acid, spirulina microalgae, and a mixture of both to analyze their bioactivation effects. These treatments were applied three times per week over the course of two weeks, with irrigation taking place every other day. The wet weight of the aerial parts of the harvested plants was measured and placed in liquid nitrogen, then stored in a freezer. Chlorophyll, carotenoids, proline, protein, phenol, antioxidants, and malondialdehyde were measured. The results show that several bioactivators significantly increased the growth, chlorophyll, carotenoids, protein, and proline of safflower plants when compared to the control. The three treatments reduced the antioxidant and malondialdehyde content significantly. In contrast to the control condition, the mixture of humic acid and spirulina microalgae, as well as humic acid alone, decreased the phenolic content. The findings demonstrated that humic acid and spirulina microalgae can serve as positive plant bioactivators for safflower by boosting its growth and reducing stress.