Effect of different nitrogenous forms on growth and chemical component in tuber of Pinellia pedatisecta Schott.

【Objectives】The effect of different ratios of ammonium to nitrate supply on Pinellia pedatisecta Schott. growth related to physiological indicators and main active ingredient content in tubers were investigated in order to provide the technical basis for Pinellia pedatisecta Schott. rational fertilization. 【Methods】A pot experiment with vermiculite growing media to Pinellia pedatisecta Schott. as test material was conducted. Different ammonium to nitrate ratios in the growing media are designed, the antioxidant protective enzymes (SOD, CAT) activity of leaves, the nitrogen metabolism (NR) activity in leaves and tubers and the content of secondary metabolites (MDA, nitrate, the main active ingredient) of tubers are measured. 【Results】 1）With the increasing of proportion of ammonium nitrogen, leaf fresh weight, tuber fresh weight and total chlorophyll content increased gradually in the overall trend. Tuber fresh weight and total chlorophyll content in total ammonium nutrition reached the highest value. 2）With the increase of the proportion of ammonium nitrogen, the activity of SOD, CAT and NR in leaves increased at beginning then decreased, the highest activity of SOD, CAT and the content of NO-3-N appeared with the ratio (50∶50) of ammonium to nitrate. 3）In total ammonium or total nitrate nutrition, MDA levels were higher than other treatments; with the ratio (50∶50) of ammonium to nitrate MDA accumulation was the lowest. 4）In total nitrate supply treatment, the NR activity in leaves, tubers reached the highest value, NR activity in leaves was higher than tubers. With the increase of the proportion of ammonium nitrogen, NR activity in leaves decreased gradually. However, NR activity in the tubers increased. 5）Cumulative main active ingredient in tubers depended on the two nitrogen fertilizers effects, the highest value achieved under the accumulation of total alkaloids, total organic acids and adenosine with a higher ratio of ammonium nitrogen treatment(75∶25).【Conclusions】Nitrogen as an essential nutrient for plant growth, nitrogen levels directly affected the growth and quality of plants. The trial found that a suitable proportion of ammonium nitrate ratio could promote the formation of the growth and yield of Pinellia pedatisecta Schott,, the promoting effect was significantly higher than the total nitrate nutrition. With ammonium nitrate ratio of 50∶50, the highest enzyme activity in plants indicates that the appropriate ratio of ammonium to nitrate can reduce the damage of the plant cell membrane lipid peroxidation; while higher NH+4-N is beneficial to the accumulation of the main active ingredient of tubers, especially for ammonium nitrate ratio of 75∶25, the cumulative effect is most significant.