OBJECTIVETo study the absorption characteristics of nitrogen (N) , phosphorus (P) , and potassium (K) of Pinellia ternate from Sichuan under the cultivated condition.

METHODThe samples of P. ternate S-29 and S-33 from Sichuan were regularly collected randomly, the contents of nitrogen, phosphorus and potassium of each part (aerial and underground parts) were determined, and their distribution and accumulation characters of nitrogen, phosphorus, potassium were also studied.

RESULTThe absorption rate of aerial and underground parts of P. ternate were different in nitrogen, phosphorus, and potassium at different growing stages. Among them, the potassium uptake was the highest, while the phosphorus uptake was the lowest. Totally, the uptakes of nitrogen, phosphorus and potassium of P. ternate from Sichuan during "sprout tumble" stage were comparatively higher than that not at "sprout tumble" stage. A significant correlation was observed between the phosphorus and potassium uptake of the aerial and underground parts, respectively (P < 0.05). And there was also significant positive correlation between the nitrogen and phosphorus uptake at underground parts (P < 0.05). During the growth stage of P. ternate, for producing 100 kg air-dried P. ternate, 5.02-5.64 kg N, 2.44-2.56 kg P205, 11.62-13.49 kg K20 were needed to be absorbed.

CONCLUSIONP. ternate from Sichuan should be given enough base fertilizer in field cultivation, and then be supplied with phosphorus and potassium by combining foliar spray with field application during the middle ten days of June and last ten days of August. The ratios of potassium should be properly improved. There was promoting effect in the phosphorus and nitrogen assimilations of the underground parts of P. ternate from Sichuan.