中文摘要：

探讨不同盐暴露浓度下玉米幼苗生理指标表现的Hormesis效应,利用阈值和Hormesis效应相结合,为污染物对生物体产生早期伤害阈值范围的确定提供理论依据。通过水培实验研究了玉米（Zea mays L.）幼苗暴露在硫酸钾（K_2SO_4）、硫酸钠（Na_2SO_4）、氯化钾（KCl）、氯化钠（NaCl）4种盐不同浓度下,对其幼苗株高变化的Hormesis效应。结果表明：在K_2SO_4暴露浓度下,玉米幼苗株高随暴露浓度的升高,先呈现＂J＂形,再呈现倒＂U＂形的变化趋势,在550 mg/L剂量组,幼苗平均株高达到最高;在不同Na_2SO_4和Na Cl暴露浓度下,玉米幼苗株高在整个实验剂量范围内,幼苗株高随暴露浓度的增加呈现下降趋势,表现＂低促-高抑＂效应,分别在50 mg/L和200 mg/L剂量组,幼苗的平均株高最高;而在KCl暴露浓度下,幼苗株高呈现＂U＂形剂量-效应曲线,在0~200 mg/L剂量,幼苗株高呈显著性增加,在200 mg/L剂量组,幼苗的平均株高最高,后呈现递减趋势。可见,玉米幼苗在低浓度盐胁迫下,表现一定的刺激效应,随暴露浓度的增加,幼苗株高随之增加或是减小,即表现＂J＂或是＂U＂形剂量-效应关系。

英文摘要：

Hormesis effect of physiological index of maize seedlings under different salt concentrations exposure was discussed, combined with the use of thresholds and the Hormesis effect, to provide a theoretical basis for the determination of pollutants producing early damage threshold range of organisms. Maize（Zea mays L.） hydroponic experiment was conducted in this study for exploring the maize seedlings exposed to potassium sulfate, sodium sulfate, potassium chloride, sodium chloride and four kinds of different salt concentrations on the change of Hormesis effect of the seedling height. The results indicated that in the K_2SO_4 exposure concentration, maize seedlings with exposure concentration increasing, presented ＂J＂ shape at first, and then the trend reversed ＂U＂ shape, average height of seedlings reached the highest in 550 mg/L dose group.In different Na_2SO_4 and NaCl exposure concentrations, during the whole experimental dose range, the plant height decreased with exposure to increasing concentrations, and the average height of seedlings was the highest respectively in 50 mg/L and 200 mg/L dose group. In the KCl exposure concentration, the plant height showed ＂U＂ shaped dose-response curve, at the dose of 0 ~200 mg/L, the plant height was significantly increased, and the average height of seedlings was the highest in 200 mg/L dose group, afterwards showing decreasing trend. The study indicates the maize seedlings under the low concentration of salt stress, show some stimulation effect, with the increase of exposure concentrations, plant height increases or decreases, which shows the ＂J＂ or ＂U＂ shape dose effect relationship.