Early Bolting, Yield, and Quality of Angelica sinensis (Oliv.) Diels Responses to Intercropping Patterns

Intercropping is a sustainable method for cultivating medicinal herbs since it requires lower dependence on chemical fertilizers than a sole cropping system. In this study, we compared the effects of sole cropping and intercropping on early bolting, yield, and the chemical composition of Angelica sinensis (Oliv.) Diels. Field experiments were conducted, in 2018 and in 2019, using different cropping systems including sole cropping of A. sinensis (AS), sole cropping of Vicia faba (VF), and intercropping (without fertilization) at three ratios: one row of A. sinensis + three rows of V. faba, AS/VF (1:3), two rows of A. sinensis + two rows V. faba, AS/VF (2:2), three rows of A. sinensis + one row V. faba, AS/VF (3:1). The effect of each cropping system was evaluated by measuring the dry biomass of V. faba and the dry biomass, ferulic acid content, and essential oil content and composition of A. sinensis. The early bolting rate of A. sinensis was significantly lower in the intercropping system as compared with that in a sole cropping system. The AS/VF (3:1) intercropping pattern resulted in an optimal yield and the highest ferulic acid content of A. sinensis, highest dry biomass of V. faba, and highest land equivalent ratio (LER). Additionally, the A. sinensis was more aggressive (the aggressivity value of A. sinensis was positive, and its competitive ratio was >1) under AS/VF (3:1) intercropping pattern, and it dominated over V. faba (which had negative aggressivity values and a competitive ratio of <1) under AS/VF (3:1) intercropping pattern. Ligustilide was the most dominant component of the essential oil of A. sinensis, regardless of the cropping system; however, the chemical component of essential oil was not influenced by intercropping patterns. Overall, the AS/VF (3:1) intercropping pattern without fertilization was the most productive, with the highest LER and ferulic acid content. These data indicate that intercropping can serve as an alternative for reducing the use of chemical fertilizers and intercropping also decreases the early bolting rate of A. sinensis, thus, enabling its sustainable production.