镉胁迫对紫丁香种子萌发及幼苗生长的影响

Effects of Cadmium Stress on Seed Germination and Seedling Growth of Syringa oblata L.

本研究以紫丁香种子和幼苗为研究对象,分析了不同浓度(0、5 mg/L、10 mg/L、20 mg/L、30 mg/L、40 mg/L)镉胁迫对种子萌发、幼苗生长生理特性及镉积累特性的影响。结果表明,随着镉胁迫浓度升高,种子各项发芽指标呈先升高后降低的趋势,在胁迫浓度为5 mg/L时发芽率最高。异常发芽率在胁迫浓度大于10 mg/L时显著升高(p<0.05)。由回归分析可知,镉胁迫对种子萌发的半致死浓度为29.95 mg/L,极限浓度为50.41 mg/L。镉胁迫对胚根生长的抑制作用要高于胚芽。随着镉胁迫浓度升高,幼苗地上、地下部干重及根冠比呈降低趋势,根系活力、抗氧化酶活性及渗透调节物质含量呈先升后降的趋势,并在胁迫浓度为10 mg/L时最高,MDA含量、质膜透性呈升高趋势,但在胁迫浓度小于10 mg/L时较对照无显著差异;镉转运系数在胁迫浓度为10 mg/L时最高,为0.54,积累量为1.25 mg/g。说明在镉胁迫浓度低于10 mg/L时,紫丁香幼苗能通过自身调节来维持正常生长,对镉胁迫具有一定耐性。

In this paper,Syringa oblata L.seeds and seedlings were used as research object,and the effects of different concentrations of cadmium(0,5 mg/L,10 mg/L,20 mg/L,30 mg/L,40 mg/L)stress on seed germination,seedling growth physiological characteristics and cadmium accumulation characteristics were analyzed.The results showed that with the increase of cadmium stress concentration,the germination index of seeds increased first and then decreased,and the germination rate was the highest when the stress concentration was 5 mg/L.Abnormal germination rate significantly increased when stress concentration was greater than 10 mg/L(p<0.05).According to the regression analysis,the semi-lethal concentration of cadmium stress on seed germination was 29.95 mg/L,and the limit concentration was 50.41 mg/L.The inhibitory effect of cadmium stress on radicle growth was higher than that of germ.With the increase of cadmium stress concentration,the above-ground and underground dry weight and root-shoot ratio of seedlings showed a decreasing trend,and the root activity,antioxidant enzyme activity and osmotic regulatory substance contents increased first and then decreased,reaching the highest at the stress concentration of 10 mg/L.The MDA content and plasma membrane permeability showed an increasing trend,but there was no significant difference compared with the control at the stress concentration of less than 10 mg/L.The highest Cd transfer coefficient was 0.54 when the stress concentration was 10 mg/L,and the accumulation amount was 1.25 mg/g.These results indicated that when the cadmium stress concentration was lower than 10 mg/L,Syringa oblata L.seedlings could maintain normal growth by adjusting their physiological activity and had a certain tolerance to cadmium stress.