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以甜瓜‘西域1号’为材料,采用营养液水培方法,研究了低氧胁迫下外源γ–氨基丁酸(GABA)对幼苗根系无机氮代谢及矿质元素含量的影响。试验结果表明,低氧胁迫下甜瓜根系中硝酸还原酶(NR)、亚硝酸还原酶(NiR)活性显著提高,硝态氮(NO3--N)、亚硝态氮(NO2--N)、铵态氮(NH4+-N)以及谷氨酸、氨基酸、总氮含量显著增加,而可溶性蛋白含量显著降低,同时K+、Ca2+、Mg2+、Zn含量显著降低,Mn、Fe、Cu含量大幅提高,根系生长受到严重抑制;低氧胁迫下添加外源GABA处理的甜瓜根系中NO3--N、NO2--N、NH4+-N、谷氨酸、氨基酸、可溶性蛋白质、总氮、K+、Ca2+、Mg2+、Zn含量以及NR、NiR活性显著高于低氧胁迫处理,而Mn、Fe、Cu含量显著降低,缓解了低氧胁迫对根系生长的抑制;低氧胁迫下同时添加GABA和钨酸钠处理的根系NR活性显著降低,同时NiR活性和NO3--N、NH4+-N、谷氨酸、氨基酸、可溶性蛋白质、总氮含量和根系干质量均显著降低。说明低氧胁迫下外源GABA可以通过诱导NR活性的提高促进硝酸盐的吸收和转化,通过提高K+、Ca2+、Mg2+、Zn的吸收和减少Mn、Fe、Cu的吸收,缓解低氧胁迫甜瓜根系的伤害。
The effect of exogenous γ-aminobutyric acid (GABA) on inorganic nitrogen metabolism and mineral elements contents in roots of seedlings under the condition of nutrient solution hydroponics was studied using the melon ’Xiyu 1’ as the material. The results showed that the activities of nitrate reductase (NR) and nitrite reductase (NiR) in melon root increased significantly under hypoxia stress. The activities of NO3 - N, NO2 - N, The content of NH4 + -N, glutamic acid, amino acid and total nitrogen increased significantly while the content of soluble protein decreased significantly while the contents of K +, Ca2 +, Mg2 + and Zn decreased significantly while the contents of Mn, Fe and Cu increased significantly The growth was severely inhibited; NO3 - N, NO2 - N, NH4 + -N, glutamate, amino acids, soluble protein, total nitrogen, K +, Ca2 +, Mg2 + Zn, NR and NiR activities were significantly higher than those under hypoxia stress, while the content of Mn, Fe and Cu was significantly reduced, and the inhibition of root growth was alleviated by hypoxia stress. Under the condition of hypoxia stress, roots treated with GABA and sodium tungstate NR activity was significantly decreased, while NiR activity and NO3 - N, NH4 + -N, glutamic acid, amino acids, soluble protein, total nitrogen and root dry weight decreased significantly. The results showed that the exogenous GABA promoted the uptake and transformation of nitrate by increasing the NR activity under hypoxia stress, and alleviated the hypoxia stress melon root system by increasing the absorption of K +, Ca2 +, Mg2 + and Zn and reducing the absorption of Mn, Fe and Cu s damage.