[Effects of nitrogen on yields and flavonoids contents of Epimedium pseudowushanense in hydroponic conditions].

Nitrogen nutrition divided into concentrations and forms for Epimedium pseudowushanense was studied under hydroponic conditions. There were 7 nitrogen concentrations treatments（N0-N6）which nitrogen concentration was 0, 2.5, 5.0, 7.5, 10.0, 13.0 mmol•L⁻¹, respectively, and 5 nitrogen forms and proportions treatments (T1-T5) which NO3-N/NH4-N was 5∶0, 4∶1, 2.5∶2.5, 1∶4, 0∶5 respectively, the total nitrogen applied was 5 mmol•L⁻¹. The results showed that along with the increase of nitrogen concentration, biomass (dry weight) and leaf dry weight increased, which in N5 treatment was 29%, 23% higher than those in N0 and 36%, 23% higher than those in N4 respectively, but not significantly different from N6 treatment. Roots and stem dry weights did not change significantly. Pn and the contents of photosynthetic pigments were higher in N3-N5 treatments. Epimedin A, B, C, icariin and total flavonoids contents were the lowest in N3 treatment, suddenly increase in N4 treatment and only a little change between N4-N6 treatments. N5 treatment with the highest epimedin C content was 131% higher than N3 treatment with the lowest epimedin C content (P<0.05). While in the nitrogen forms and proportions treatments, biomass, leaf and stem dry weights were the highest in T3 treatment and lower in T1 and T5 treatments, without significance between T1 and T5 treatments. These indicators in T3 treatment were more than 30% higher than those in T1 treatment. The impact of nitrogen concentrations was greater than nitrogen forms on flavonoids. epmedin C content was the highest in T1 treatment, only 5%-8% higher than that in T2-T5 treatments (no significance between 4 treatments). Epimedin A, B, icariin and total flavonoids contents were higher in T1 treatment, the lowest in T2 treatment, those in T1 treatment was 41%, 62% and 27% higher than T2 treatment respectively (P<0.05). In a conclusion, E. pseudowushanense is a high nitrogen tolerant plant, 10.0 mmol•L⁻¹ was the boundary point between growing general to well and the optimal nitrogen concentration for it was 10.0-13.0 mmol•L⁻¹. Besides, it prefers to grow in NO-3 plus NH+4 and the optimal proportion was 2.5∶2.5.