Biostimulant Effects of Seaweed Extract and Amino Acids On Growth, Antioxidants, and Nutrient Content of Yarrow (Achillea millefolium L.) In the Field and Greenhouse Conditions

Abstract

The aim of this study was to investigate the effect of foliar spray of seaweed extract (SE) and amino acids (AA) on growth characteristics, antioxidant activity, and nutrient elements of yarrow (Achillea millefolium L.) in the field and greenhouse conditions. The experiment was conducted as a randomized complete block design with six replications. Treatments included foliar spray of SE (1, 2, and 3 ml l−1) and AA (1.5 and 3 ml l−1) along with the control. The results showed that the application of different levels of SE and AA had positive effects on the growth indices, chlorophyll content, carotenoids, antioxidants, and nutrient content of yarrow in the field and greenhouse conditions. In the greenhouse, the highest shoot dry weight was obtained by the application of SE and AA at a concentration of 3 ml–l with 54% and 53% increase compared to the control. Foliar spray of SE and AA increased the total phenols, total flavonoids, and antioxidant activity of the leaf and flower of yarrow in the field and greenhouse conditions. Under field conditions, the highest antioxidant activity of flowers was obtained from 3 ml l–l AA treated plants by 17% increase compared to the control. The content of N, P, and K in the leaf was improved by foliar spray of SE and AA. In particular, the application of 2 ml l−1 SE and 3 ml l−1 AA had the most significant effect in improving the growth and yield of yarrow in the field and greenhouse experiments.