硝铵比例影响小白菜生长和叶绿素含量的原因探究

Influence of NO_3^-∶ NH_4^+ ratio on growth and chlorophyll content in pakchoi

采用溶液培养试验研究了不同NO3-∶NH4+比例,分别为5.00∶0.00、3.75∶1.25、2.50∶2.50、1.25∶3.75和0.00∶5.00(mmol/L)对小白菜生长和叶绿素含量的影响及其原因。结果表明,1)与纯硝营养相比,NO3-∶NH4+为3.75∶1.25(mmol/L)时,小白菜具有最大的生物量、叶面积和叶片细胞分裂素含量;2)SPAD值、叶片可溶性蛋白质和活性铁含量均随着铵态氮比例的增加而增加;3)叶片细胞分裂素含量与叶面积、叶面积与生物量间的相关显著,相关系数(r)分别为0.97、0.95(P<0.05);SPAD值与叶片可溶性蛋白质以及和活性铁含量之间的相关系数(r)分别为0.99和0.97(P<0.05)。适当提高铵态氮比例可以增加小白菜叶面积可能是因提高了叶片细胞分裂素含量从而促进其扩展,进而影响生物量;提高铵态氮比例可以提高叶绿素含量,与提高了叶片蛋白质和活性铁的含量有关。

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, P 〈 0.05）, and the leaf area was significantly correlated with biomass （r = 0.95, P 〈 0.05） ; SPAD readings was significantly correlated with soluble protein content and active iron content, with correlation coefficients （r） being 0.99 and 0.97 （ P 〈 0.05）, 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.