Growth, Physiological Responses and Secondary Metabolite Production in Pinellia Ternata under Different Light Intensities

Pinellia ternate (Thunb.) Breit (Araceae) is a shade-tolerant perennial medicinal plant, but its optimum light intensity is not sufficiently known. Hence, the influence of light intensity on the physiological responses, growth and secondary metabolic products in P. ternata under four light conditions (15%, 25%, 45% and 100% of full sunlight) in a greenhouse were to be investigated. The results show that the fresh and dry tuber weight, leaf area, tuber number and propagation index were highest in P. ternata grown under the intermediate light level (45% sunlight). In contrast, 15% sunlight induced the lowest growth parameters but the highest plant height. Sunlight from 15% to 45% significantly increased the chlorophyll concentration compared to that under full sunlight conditions. Moreover, 100% sunlight enhanced the POD and CAT activities and induced MDA, total alkaloid, guanosineand succinic acid accumulation. The maximum yields of total alkaloids, guanosineand succinic acid occurred under 45% sunlight. Overall, 45% sunlight was the most efficient way of improving the tuber yields and qualities of P. ternata. These results suggest that P. ternata is suitable for growth in a moderate-low-light environment and an appropriate light control can produce higher tuber and secondary metabolite yields within agroforestry systems.