Effect of nitrate concentration on plant growth and anthocyanin accumulation in the ornamental bromeliad Alcantarea imperialis

Alcantarea imperialis (Carrière) Harms is a large bromeliad species with showy inflorescence widely used in landscape projects. When grown in vitro under different nitrogen (N) concentrations, its normally green leaves show red coloration. Thus, the aim of this study was to evaluate the in vitro growth of A. imperialis plants and identify the anthocyanins present on their leaves. Plants obtained from seeds were cultivated in vitro for six months in Murashige and Skoog (MS) medium with varying N concentrations (3.75, 7.5, and 15 mM NO3−) and transferred to the greenhouse where they remained for 12 months. The number of leaves and roots, length of aerial parts and roots, mass of shoot and root parts, photosynthetic pigment contents (chlorophyll a, b, and carotenoids), and anthocyanin levels were determined. During in vitro cultivation, anthocyanin levels increased with increasing N concentrations. The presence of pelargonidin, cyanidin and delphinidin glycosides in A. imperialis leaves was identified by high-performance liquid chromatography (HPLC). Using NO3− as N source enhanced plant growth and anthocyanin accumulation in A. imperialis.