氨基酸部分取代硝态氮对小白菜硝酸盐累积的影响

采用水培试验研究了氨基酸和硫酸铵部分取代硝态氮对小白菜硝酸盐含量及营养品质的影响.结果表明,谷氨酸与谷氨酰胺等氮量配合(Glu+Gln)部分取代硝态氮对小白菜地上部鲜重和干重的影响较小,但谷氨酸(Glu)和硫酸铵(NH₄)2SO₄]导致鲜重显著下降,并且Glu使干重也显著下降.氨基酸和硫酸铵部分取代硝态氮均降低小白菜可食部分的硝酸盐的含量,但氨基酸效果更好,依次为Glu>Gln>Glu+Gln;氨基酸部分取代硝态氮均促进小白菜对磷和钾养分的吸收,Gln促进氮的吸收,均提高地上部分的全氮、全磷和全钾的含量;氨基酸和硫酸铵部分取代硝态氮均使小白菜的品质有不同程度提高,其中可溶性糖的含量,除Glu+Gln处理外其他处理都显著高于对照,并以(NH4)2SO4效果最好;Glu能显著增加维生素C的含量,其他处理不显著;除Gln外,各处理均显著增加游离氨基酸的含量,并以Glu+Gln处理效果最佳;Glu和Gln显著增加可溶性蛋白的含量,而(NH₄)₂SO₄和Glu+Gln对可溶性蛋白质含量无明显影响.氨基酸和硫酸铵对小白菜硝酸盐含量及营养品质的影响与其对根系活力,叶绿素含量、谷草转氨酶(GOT)、谷丙转氨酶(GPT)活性的提高作用有关.

Influence of partial replacement of nitrate by amino acids on nitrate accumulation of pakchoi(Brassica chinensisL.)

Influence of partial replacement of nitrate by amino acid and ammonium sulfate on nitrate content and nutritional quality of pakchoi (Brassica chinensis L.) was studied adopting hydroponics test. Partial replacement of nitrate by the mixture of glutamic acid and glutamine (Glu Gln) had less influence on shoot fresh weight and dry weight of pakchoi; while Glu and ammonium sulfate markedly decreased fresh weight and Glu significantly reduced dry weight. Partial replacement of amino acids and ammonium sulfate all decreased content of the eatable part nitrate of pakchoi, while amino acids had better effect with Glu>Gln>Glu Gln in proper order. Partial replacement of amino acids all promoted the uptake of phosphorus and potassium nutrients by pakchoi. Gln promoted uptake of nitrogen, and all raised the contents of total nitrogen, phosphorus and potassium of shoot. Partial replacement of amino acid and ammonium sulfate all raised the pakchoi quality to different degree, in which except Glu Gln treatment, all other treatments had a significantly higher soluble content than the contrast and the effect of (NH4)2SO4 was the best. Glu increased significantly the content of vitamin C, while others treatments could not increased significantly. All treatments, except Gln treatment, increased significantly free amino acid content, and the effect of Glu Gln treatment was the best. Glu and Gln increased obviously the soluble protein content, while (NH4)2SO4 and Glu Gln had no obvious influence on soluble protein content. The influence of amino acids and ammonium sulfate on nitrate content and nutritional quality of pakchoi was related to the enhancement of root activity, chlorophyll content, glutamate-oxaloacetate transaminase (GOT) and glutamate-pyruvate transaminase (GPT) activities.