铝胁迫对紫花苜蓿生长及根系发育的影响

Effect of aluminum stress on shoot and root growthof alfalfa under acidic conditions

摘要:

对2个紫花苜蓿(Medicago sativa)品种德钦和游客在不同浓度Al³⁺(0,50,100,200,500 mol/L)胁迫下的根长、株高、生物量、根系活力、SOD、POD活性等指标进行研究。结果表明:苜蓿的根部经苏木精染色后,供试紫花苜蓿根部的颜色随Al³⁺浓度上升而加深。不同浓度Al³⁺均明显抑制了紫花苜蓿品种根和株高的生长。与对照相比紫花苜蓿根长、株高、地上和地下生物量随Al³⁺浓度的增加明显降低。在较低浓度的Al³⁺处理下(≤200 mol/L)游客苜蓿根长的抑制率小于德钦苜蓿,而当Al³⁺胁迫达到较高浓度时(500 mol/L),游客苜蓿根长受抑制率大于德钦苜蓿。随着Al³⁺浓度的增加,两个紫花苜蓿品种的根系活力、POD、SOD活性下降,丙二醛含量增加。在酸性土壤条件下,紫花苜蓿地方品种德钦对高铝浓度表现出较高的适应性,游客在低铝浓度下表现出较强适应性。

Abstract:

In south of China,aluminum stress is a barrier factor for alfalfa planting in acid soils,inhibition of root growth is a typical symptom of plants under aluminum stress.It is of great economic significance to study the aluminum toxicity of plant roots for the cultivation of alfalfa in southern China.In this study,two kinds of alfalfa (Medicago sativa) (Deqin and Eureka) in acidic soil was studied under aluminum stress.The effects of different AL³⁺ concentrations (0,50,100,200,and 500 mol/L) on root length,plant height,biomass,root activity,SOD,and POD of alfalfa were analyzed.After the roots of alfalfa were stained with hematoxylin,the color of alfalfa roots deepened with the increase of Al³⁺ concentration.The results showed that the different concentrations of aluminum significantly inhibited the root and plant height growth of the two alfalfa species.Compared with the control,the root length,plant height,aboveground biomass,and underground biomass of alfalfa decreased significantly with the increase of Al3+ concentration,and there were significant differences between different varieties.Under the relatively low concentration of aluminum stress (≤200 mol/L),the inhibition rate of root length in Eureka was less than that of Deqin,while the inhibition rate of root length in Eureka was greater than that of Deqin when aluminum stress reached at high level.With the increase of the concentration of aluminum,the activity of root system,POD,and SOD decreased,the content of malondialdehyde increased,and the difference between different varieties was significant.In conclusion,under different acidic soil conditions,a local variety alfalfa Deqin and a popularized variety Eureka showed different aluminum tolerance.