氮水平和形态对水培桔梗生长及氮磷吸收的影响

Effect of Nitrogen Levels and Forms on Growth and Uptake of Nitrogen and Phosphorus of Hydroponic Platycodon grandiflorum

以水培桔梗为试材,研究氮水平(N1、N2.5、N5、N7.5)和氮形态(N5、N4+A1、N2.5+A2.5、N1+A4)对桔梗生长及氮磷元素吸收的影响。结果表明,氮水平下桔梗鲜质量N1、N2.5和N5根系高于地上部,干质量N1、N7.5地上部高于根系;地上部、根系干质量分别在N7.5、N5最大;叶绿素、地上部和根系鲜质量N7.5和N5高于N2.5和N1,根鲜质量N5稍高于N7.5;氮含量和吸收量地上部高于根系,磷含量N2.5、N5和N7.5根系高于地上部,磷吸收量N1、N7.5地上部高于根系,N2.5、N5相反;地上部氮吸收量N7.5最大,全株氮含量和根系氮吸收量N7.5和N5高于N1和N2.5;地上部氮磷吸收量、根系磷含量及吸收量N7.5最大,根中磷含量及吸收量随着氮浓度增加而减小。氮形态各处理中干、鲜质量地上部大于根系;各生物量指标N1+A4最低,根长随硝铵比降低而减少;地上部质量N4+A1高于N2.5+A2.5、N5+A0,根干、鲜质量N5+A0最大,N2.5+A2.5次之;氮吸收量除N1+A4外地上部高于根系,氮含量N5+A0、N4+A1地上部高于根系,其他2个处理相反;磷含量各处理根系高于地上部,磷吸收量除N1+A4外根系低于地上部;随硝铵比增加,地上部氮含量和根系磷吸收量减少,根系氮、磷含量分别在N1+A4、N2.5+A2.5最大;地上部氮磷吸收量N4+A1最大,N2.5+A2.5次之。可见,设施无土栽培可用于桔梗生产,适宜的氮水平和氮形态分别是5 mmol/L和5 mmol/L硝态氮没有铵态氮。营养液中硝态氮和铵态氮组成为1 mmol/L NO-3-N+4 mmol/L NH+4-N时桔梗易遭受氨毒危害。

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.