Abstract: Effect of nitrogen nutrition conditions on growth and absorption of nitrogen and phosphorus of Platyc-odon grandiflorum were studied by designing 4 nitrogen levels ( N1、N2.5、N5、N7.5 ) and 4 nitrogen forms ( N5、N4+A1、N2.5+A2.5、N1+A4) of Platycodongrandiflorum as test material.The results showed that:roots were higher than shoots of root fresh weight in N 1,N2.5 and N5 of Platycodon grandiflorum,and shoots were higher than root of dry weight in N1 and N7.5.The maximum of dry weight on shoot and root were existed in N 7.5 and N5 re-spectively.Chlorophyll content and fresh weight of shoot and root in N 7.5 and N5 were higher than that of N2.5 and N1,root fresh weight of N5 was slightly higher than N7.5.Nitrogen content and uptake of shoots were higher than root,and phosphorus content of N2.5,N5 and N7.5 in roots were higher than shoots,phosphorus uptake a-mount of shoots in N1 and N7.5 were higher than that of roots, and phosphorus uptake amount in N 2.5 and N5 were instead.The maximum of nitrogen uptake of shoots were in N 7.5, the nitrogen content of whole plant and root nitro-gen uptake of were higher than that of N 1 and N2.5.The maximum of nitrogen and phosphorus uptake of shoots, phosphorus content and uptake of root were N 7.5,andthe absorption of phosphorus in root decreased with nitrogen concentration increasing.Dry and fresh weight of shoots was higher than roots in all treatments of nitrogen forms.All biomass index were minimum of N 1+A4, and root length were decreased with ammonium nitrate ratio.Shoot fresh weight of N4+A1 were higher than that of N 2.5 +A2.5 and N5 +A0, and the maximum of root dry and fresh weight were N5+A0,and the second was N2.5+A2.5.Nitrogen uptake of shoots were higher than that of roots ex-cept N1+A4, of shoot in N5+A0 and N4+A1 were higher than that of roots, however nitrogen content of other two treatments were instead.In all treatments phosphorus content of roots were higher than that of shoots, and phosphor-us uptake of shoots were lower than that of roots in addition to the N 1+A4.Nitrogen content of shoots and root phosphorus uptake decreased with ammonium nitrate ratio increasing, the maximum of nitrogen and phosphorus con-tent in root were N1+A4 and N2.5+A2.5,respectively.The maximum of nitrogen and phosphorus uptake were N 4+A1,and N2.5+A2.5 was second.Thus it can be seen,soilless culture can be used for the production of Platyc-odongrandiflorum,and the most proper nitrogen levels were 5mmol/L,and nitrogen forms were 5 mmol/L NO3--N and no NH4+-N.Platycodon grandiflorum were vulnerable to ammonia toxicity hazards in the nutrient solution of 1 mmol/L NO₃^--N+4 mmol/L NH₄⁺-N.

Key words: NitRogen level, NitRogen foRm, HydRoponics, NitRogen and phosphoRus uptake, Platycodon gRandifloRum

CLC Number: 

• S567.239