Fontes e doses de fósforo na produção de biomassa e no teor de flavonoides em Calendula officinalis L.

Abstract

Calendula (Calendula officinalis L.) is widely cultivated for its ornamental, medicinal, and industrial value, especially due to the flavonoids found in its flowers. Proper fertilization management, particularly phosphorus supply, is essential for biomass and bioactive compound production. This study aimed to evaluate the effect of different phosphorus fertilizer sources and doses on the growth and flavonoid content of calendula. The experiment was conducted in a randomized block design with a factorial scheme (2 sources × 5 doses) and four replications. Two phosphorus sources were tested: monoammonium phosphate (MAP) and an organomineral fertilizer (Evolutions®), applied at doses of 0, 25, 50, 100, and 150 kg ha⁻¹. After 120 days of sowing, growth parameters, dry weight of various plant parts, and chlorophyll and flavonoid contents were evaluated. No significant interaction was observed between fertilizer source and dose for growth variables. However, MAP led to a greater stem diameter (20.33 mm) compared to the organomineral fertilizer (17.91 mm), while the latter resulted in higher shoot dry weight. Increasing fertilizer doses improved dry biomass. Regarding flavonoid content, MAP resulted in higher levels (0.561%) than the organomineral source (0.330%), with the highest values observed at 0 kg ha⁻¹ (0.636%) and 100 kg ha⁻¹ (0.656%) of MAP. It is concluded that phosphorus fertilization using MAP promotes greater stem diameter and more efficient accumulation of flavonoids in calendula compared to organomineral fertilization.