中文摘要：

为优化不同形态氮浓度配比,提高设施栽培蔬菜营养品质,在局部无菌水培条件下,研究了不同外源甘氨酸态氮、硝态氮和铵态氮的浓度配比对小白菜生物量、根系形态及营养品质的影响。结果表明,小白菜生物量及其营养品质受外源氮浓度组成影响差异显著(P<0.05)。在高甘氨酸态氮(2500μmol·L-1)和铵态氮(2500μmol·L-1)、低硝态氮(250μmol·L-1)浓度处理中,小白菜生物量最高,达94.5 mg·株-1,且小白菜总根长、根表面积、根体积、根系活力等指标的变化趋势与生物量一致;在高甘氨酸态氮、低无机氮浓度处理中,小白菜可溶性蛋白、游离氨基酸和可溶性糖含量最高,分别为26.2、126、24.0 mg·kg-1,且硝酸盐含量较高无机氮处理显著降低(P<0.05)。适当提高甘氨酸态氮浓度、降低无机氮(尤其是硝态氮)浓度能够一定程度改善其营养品质。

英文摘要：

Plants not only absorb nitrate(NO-3-N)and ammonium(NH+4-N), but also have the ability to take up intact amino acids, such as glycine(Gly-N). It has been known that exogenous nitrogen(N)form in fertilizers is a major factor determining the nitrate accumulation and nutritional quality of plant edible parts. However, the effects of applying different N form mixture on plant growth and nutritional quality are still poorly understood. In this study, the effects of different concentrations and forms of exogenous Gly-N, NO-3-N, and NH+4-N on biomass, root morphology and nutritional quality of pakchoi (Brassica chinensis L.)were explored under partial sterile hydroponic cultivation con-dition. Results showed that the biomass and nutritional quality of pakchoi was significantly affected by the ratios of three N forms(P﹤0.05). The highest pakchoi biomass(94.5 mg·plant-1)was achieved in the treatment supplied with high Gly-N(2500 μmol·L-1), high NH+4-N (2500μmol·L-1), and low NO-3-N(250μmol·L-1). The total root length, total root surface area, total root volume, and root activity followed a similar variation trend to the pakchoi biomass. Simultaneous applications of high Gly-N and low inorganic N resulted in the highest con-tent of total soluble proteins, total free amino acids, and total soluble sugars in pakchoi plants(about 26.2 mg·g-1, 126 mg·kg-1, and 24.0 mg·kg-1, respectively). Accumulation of nitrate was significantly decreased by high Gly-N and low inorganic N treatments, compared with the high inorganic N treatments(P﹤0.05). It suggests that appropriate formula of N sources, particularly higher Gly-N while in lower NO-3-N, can partly improve the nutritional quality of pakchoi under sterile hydroponic conditions. Our results shed light on nutritional quality im-provement of vegetables by optimizing the composition of different N forms in protected vegetable cultivation.