硝态氮与铵态氮配合缓解黄瓜苗期铵毒害作用的研究

Studies on Effects of Nitrate Nitrogen and Ammonium Nitrogen Combination on Alleviating Ammonium Toxicity in Cucumber Seedlings

为明确硝态氮在缓解黄瓜苗期铵毒害的作用及相关机制,采用盆栽试验的方法,以‘津研4号’黄瓜为试验材料,以蛭石为育苗基质,在总氮浓度为15 mmol/L的条件下,苗期分别供给铵态氮与硝态氮,出苗5周后,测定黄瓜生长及生理相关指标。结果表明,在全NH_(4)^(+)-N处理条件下,极易产生铵毒害。全NO_(3)^(-)-N处理下,幼苗地上部全氮与全磷含量分别为全NH_(4)^(+)-N处理的1.08倍与1.11倍,叶面积、生物量及壮苗指数显著高于全NH_(4)^(+)-N处理;全NH_(4)^(+)-N供给条件下,地上部MDA含量显著高于全NO_(3)^(-)-N处理,而叶绿素含量却显著低于全NO_(3)^(-)-N处理,生长明显受抑;在NH_(4)^(+)-N中混入等量NO_(3)^(-)-N后,抑制作用减弱,幼苗根际pH由6.28上升至6.54,叶绿素含量与叶面积均有不同程度增加,地上部与根系干重较全NH_(4)^(+)-N处理分别增加了26.6%与29.5%,壮苗指数与全NO_(3)^(-)-N处理间无显著差异。研究认为,NO_(3)^(-)-N对铵毒害有一定的缓解作用,且缓解作用依赖于幼苗自身营养与生理代谢的平衡。

To explore the effects of NO_(3)^(-)-N on alleviating ammonium toxicity and mechanism involved at cucumber seedling stage,a pot experiment was carried out.In the experiment,the variety of‘Jinyan No.4’was selected as the experimental material,and vermiculite was used as the seedling substrate.The total nitrogen concentration was 15 mmol/L,NH_(4)^(+)-N and NO_(3)^(-)-N were supplied respectively at seedling stage.5 weeks later,the growth and physiological indexes of cucumber seedlings were measured.The results showed that it was easy to cause toxicity,if only NH_(4)^(+)-N was supplied.The contents of total nitrogen and total phosphorus in shoots treated by NO_(3)^(-)-N were 1.08 times and 1.11 times higher than those treated by NH_(4)^(+)-N,respectively.Meanwhile,the leaf area,biomass and seedling’s quality index were significantly higher than those treated by NH_(4)^(+)-N.For seedlings only supplied with NH_(4)^(+)-N,MDA content in shoots was significantly higher than that of NO_(3)^(-)-N treatment,but chlorophyll content was significantly lower than that of NO3--N treatment.The growth was significantly inhibited by NH_(4)^(+)-N.When NH_(4)^(+)-N was mixed with the same amount of NO_(3)^(-)-N,the inhibition was weakened.The pH value of seedlings rhizosphere increased from 6.28 to 6.54,at the same time chlorophyll content and LA increased in a degree.The shoots and roots dry weights increased by 26.6%and 29.5%,respectively.There was no significant difference in seedling’s quality index between NH_(4)^(+)-N treatment and NO_(3)^(-)-N treatment.It is concluded that ammonium toxicity is relieved by NO_(3)^(-)-N,and the beneficial effect depends on the balance of nutrition and physiological metabolism of seedlings.