Impact of photoselective colored nets on growth, anatomy, iridoid and phenolic content, and antioxidant capacity of the endangered medicinal plant Stachytarpheta sellowiana Schauer

Stachytarpheta sellowiana is a medicinal plant native to Brazil that is at risk of extinction. Light is one of the environmental factors directly influencing plant growth, anatomy, and metabolite production. The study aimed to assess the spectral influence of light transmitted through photoselective colored nets on the vegetative growth, anatomical features, metabolites (photosynthetic pigments, iridoid, phenols, and total flavonoids), and antioxidant capacity. The study followed a completely randomized experimental design, with four treatments: black, red, blue, and sunlight. Parameters leaf area, photosynthetic pigments, and length of the longest branch showed higher values in plants cultivated under blue and black nets. Plants grown under sunlight recorded higher dry weight accumulation. The best values recorded for parameters leaf area, photosynthetic pigments, and plant length were observed in plants grown under blue and black nets. In addition, significant differences were observed in anatomical features among all treatments. Plants grown under blue net accumulated larger amounts of total iridoids and showed higher antioxidant capacity. Photoselective colored nets changed the growth, anatomy, metabolite production, and antioxidant capacity. This species can be cultivated under sunlight to achieve higher dry weight accumulation. However, cultivation under blue nets is recommended for higher production of antioxidant compounds and iridoids.