Adubação verde associada com biofertilizante no crescimento e produção de flavonóides de Calendula officinalis L.

Abstract

Calendula officinalis, popularly known as calendula, belongs to the Asteraceae family. The flower heads of this species are rich in secondary metabolites, such as flavonoids, which have anti-inflammatory, antioxidant and healing properties. The development of cultivation technologies, such as the use of green manure, is relevant to give sustainability to the production system of medicinal species. In this sense, the objective of this research was to evaluate the use of green manure associated with Vairo biofertilizer in the growth and production of flavonoids in calendula. Green manure species such as Crotalaria juncea L. and Pennisetum glaucum (L.) R. Br. were cultivated in an experimental area. In addition to these treatments, bare soil (control) and residues from spontaneous vegetation were used. Subsequently, the plants were bedded on the soil surface with the aid of a knife roller. After the rolling process, calendula seeds were deposited directly in the sowing furrow, with or without the spraying of Vairo biofertilizer. A randomized block design in split plots was used, with four replications, with the use of biofertilizer arranged in the plots (36 m2 ) and the cultivation systems using green manure species, spontaneous vegetation, and uncovered soil in the subplots (9 m2 ). After 120 days of calendula cultivation, the following were evaluated: length of the aerial part, stem diameter, dry weights of plants and floral capitula, chlorophyll index, and flavonoid content. Pre-cultivation using crotalaria or millet promoted higher averages in plant growth, regardless of the use of biofertilizers. However, the combination of millet crop residues with Vairo biofertilizer increased the flavonoid content in the flowers. The combination of green manures and biofertilizers presents itself as a promising strategy for the sustainable cultivation of calendula, maximizing both the yield of vegetable raw material and the flavonoid content.