Dry matter accumulation of Pinellia ternata and its characteristics of nitrogen, phosphorus and potassium absorption

Pinellia ternata Breit is a Chinese traditional medicinal herb. Because of the various medical effects and growing market demand, planting area of P. ternata is increasing in China. In this paper, the dynamics of the dry matter accumulation, and the N, P, K contents of P. ternata at the crop’s different development stages were studied. Results show that the dry matter accumulation rates of P. ternata are relatively lower in seedlings and late growth stages (sprout tumble periods), and higher in bulbis and tuber expanding stages. The absorption rates of N, P and K have the same dynamic regulation with dry matter accumulation, and the absorptive capacities of N, P and K are different. Both in the first growth season and in the second growth season, the absorptive capacities are relatively lower within 30 growth days, which only account for 30.6%, 27.7% and 27.8% of the season total absorptive capacities of N, P and K, respectively, while the capacities increase rapidly within 60 growth days, account for 43.6%, 52.3% and 49.0%, and the capacities decrease after 60 growth days. In the whole growth year (the two growth seasons), the absorptive capacity of N is highest, and the absorptive capacity of K is higher than that of P.