NO_3^-/NH_4^+配比对镉胁迫下小白菜镉含量和生理指标的影响

Effect of NO_3^-/NH_4^+ Ratio on Cadmium Content and Physiological Index in Chinese Cabbage under Cadmium Stress

探讨了NO3-/NH4+不同配比(10:0、7:3、5:5、3:7、0:10)对植物的镉吸收累积及生理方面的影响。Hoagland营养液为基础,以小白菜为材料,研究了NO3-/NH4+不同配比对镉胁迫下(1mg/L)小白菜生长、镉累积及全氮、全碳含量的影响。结果表明:在1mg/L镉处理下,以NO3-/NH4+配比为5:5时,株高最大,并显著高于对照;NO3-/NH4+配比为7:3时,地上部鲜重、干重与地下部鲜重、干重均为最大,而各处理之间根冠比差异不显著;净光合速率、蒸腾效率随NH4+浓度的增加呈先增加再降低的趋势,并以NO3-/NH4+配比为7:3时最大,胞间CO2浓度的变化则与之相反;不同NO3-/NH4+配比处理后,地上部全碳含量随NH4+浓度的升高呈逐渐增加趋势,而地下部全碳含量则为不同NO3-/NH4+配比处理均高于对照;地上部全氮含量随NH4+浓度的增加呈逐渐降低趋势,且不同NO3-/NH4+配比处理均小于对照,地下部全氮含量除NO3-/NH4+配比为3:7处理外,其余处理均高于对照;地上部镉含量以NO3-/NH4+为7:3时为最小,且随NH4+浓度增加,小白菜地上部对镉的吸收呈增加趋势,而各处理的地下部镉含量均高于地上部镉含量。在1mg/L镉处理下,以NO3-/NH4+为7:3时小白菜地上部对镉的吸收累积最少;增加NH4+浓度能加速小白菜地上部对镉的吸收。

The purpose was to discuss the effect of different NO3^-/NH4^＋ ratio （10：0,7：3,5：5,3：7,0：10） on Cadmium content and physiological indexes of plant under Cadmium stress. [Method]With Chinese white cabbage as tested material, effect of NO3^-/ NH4^＋ ratio on the growth, Cadmium content and contents of total nitrogen, total carbon under Cadmium stress （1 mg/L） were studied on the basis of Hoagland nutrition. Under Cd stress（ 1 mg/L）, hight of plant was the highest at a 5：5 ratio,and lower than the control;Above-and belowground biomass arrived at peak value at a 7：3 ratio,but root/shoot ratio was not significant difference among treatments.Pn and Te showed a trend of increasing firstly and reducing again with increasing of NH4^＋ eoncentration, and there was the highest at NO3^-/NH4^＋ ratio of 7：3,while the changing pattern in Ci was contrary to Pn. With increasing of NH4^＋ concentration,content of total carbon aboveground elevated, and contents of total carbon belowground in each treatment were higher than that of the control.Contents of total nitrogen aboveground reduced with increasing of NH4^＋ coneentration,and contents of total nitrogen in each treatment were lower than that of the control.Content of Cd aboveground has a trend of increasing with adding of NH4^＋coneentration,and there was the lowest content at NO3^-/ NH4^＋ ratio of 7：3,but content of Cd belowgroun was higher than that aboveground.Shoot of Chinese white Cabbage had less absorbed to Cd at NO3^-/NH4^＋ ratio of 7：3 under Cadmium Stress（1mg/L）;Shoot of Chinese white Cabbage absorbed more Cadmium at more NH4^＋ concentrations.