Physiological characteristics, dry matter, and active component accumulation patterns of Changium smyrnioides in response to a light intensity gradient

Abstract

Context:Changium smyrnioides Wolff (Apiaceae) is an endangered medicinal plant with numerous pharmacological uses.

Objective: To investigate the effect of light intensity levels on the growth and accumulation of secondary metabolites of C. smyrnioides, cultivated seedlings were subjected to different relative light intensities via sun-shading.

Materials and methods:Changium smyrnioides seedlings were subjected to five irradiance treatments (100, 60.54, 44.84, 31.39, and 10.56% sunlight) in glasshouse for 9 months. Enzymatic and non-enzymatic antioxidants with spectrophotometric method, photosynthetic parameters with Li-6400XT, dry matter accumulation and active component contents in the root with spectrophotometric and HPLC method were analyzed.

Results: With an increase in relative light intensity levels, activities of enzymatic and non-enzymatic antioxidants, and malondialdehyde (MDA) contents were increased overall, while net photosynthetic rate (P_n) and dry matter accumulation patter first increased and then declined. The highest net photosynthetic rate (30.68 μmol/m²·s) and dry root weight (5.07 g) were achieved under 60.54% sunlight. Lower relative light intensity levels stimulated the accumulation levels of bioactive compounds in the roots so that the highest contents of mannitol (1.35%) and choline (405.58 μg/g) were recorded under 31.39% sunlight, and the highest polysaccharide content (10.80%) were achieved under 44.84% sunlight. With a decrease in the relative light intensity levels, the water-soluble component content increased first and then decreased.

Discussion and conclusion: The results revealed that 31.39–60.54% sunlight serve as appropriate relative light intensity conditions for cultivated C. smyrnioides.