Influence of NO3-∶ NH4+ ratio on growth and chlorophyll content in pakchoi

An experiment with solution culture was carried out to investigate the effects of NO3-∶NH4+ ratio(5.00∶0.00,3.75∶1.25,2.50∶2.50,1.25∶3.75 and 0.00∶5.00 in mmol/L) on growth and chlorophyll content in pakchoi.Results obtained are listed as following: 1) Pakchoi had a maximum biomass,leaf area and cytokinins content contrast to pure(nitrate) nutrition cultivated at NO3-∶ NH4+ ratio equivalent to 3.75∶1.25 in mmol/L;2) SPAD readings,content of soluble protein and active iron in leaf enhanced with increasing of NH4+-N proportion;3) Cytokinins content was significantly correlated with leaf area(r =0.97,P0.05),and the leaf area was significantly correlated with biomass(r=0.95,P0.05);SPAD readings was significantly correlated with soluble protein content and active iron content,with correlation coefficients(r) being 0.99 and 0.97(P0.05),respectively.Properly increasing ammonium proportion influenced leaf area.The possible underlying mechanism was that it increased cytokinins content,then leaf blade expanded which influenced biomass of pakchoi consequently;Increasing ammonium proportion also influenced chlorophyll content because it enhanced soluble protein and active iron content which consequently increased chlorophyll-protein compounds content.