Impact of Transplanting Date and Animal Manure Fertilizer on Yield and Yield Components of Yarrow (Achillea millefolium L.)

Finding the appropriate fertilizer level and the best transplanting dates of yarrow as one of the most important medicinal plants can help farmers achieve better cultivation results. Therefore, this study aimed to determine yarrow optimal transplanting dates and animal manure level and to investigate the effect of these two factors on yield and seed yield components. A split plate experiment was carried out based on a randomized complete block design in three replications during 2021-2022. The experimental treatments consisted of animal manure fertilizer as the main factor (0, 10, 20, 30 ton ha-1) and transplanting dates (April 4, April 24, May 14) as the sub-factor. The studied traits included essential oil content, yield, and seed yield components. The results showed that the application of animal manure has a positive effect on the numbers of inflorescences (0.77 m-2), florets (216.3 m-2), flowering stems (6.3 m-2), seeds per inflorescence (78840 m-2), and thousand seed weight (3.6 g). April 4 was the best transplanting date in terms of the evaluated traits. The highest essential oil yield (2.2 g m-2) was observed for 30 ton ha-1 animal manure treatment on April 4. In general, based on the results of this study, applying 30 ton ha-1 of animal manure and choosing April 4 as the transplanting date can promote essential oil content, yield, and seed yield components. Therefore, it is possible to consider the use of animal manure as an organic fertilizer to improve the yield of medicinal plants, including yarrow.