SHADE TOLERANCE OF MARIGOLD PLANTS (Calendula officinalis)

Pot marigold (Calendula officinalis L.) is the second most commonly-sold medicinal herb in Colombia. The study was performed in Tunja, Colombia, in which chlorophyll and carotenoid content were evaluated in pot marigold grown under low and high light conditions (35% and 100% of full daylight). Chlorophyll fluorescence parameters and electron transport rate were also evaluated. Compared to full sun plants, shaded plants had a higher ratio of chlorophyll a to chlorophyll b, and a lower ratio of carotenoids to chlorophyll. Values for maximum fluorescence (Fm), variable fluorescence (Fv), and maximum quantum efficiency of photosystem II (the ratio Fv/Fm) increased in shaded plants, while electron transport rate was reduced. These results suggest that pot marigold plants are very sensitive to low-light conditions