镨对镉胁迫下水稻幼苗根系生长和根系形态的影响

为了解稀土镨对镉胁迫下水稻(Oryza sativa L.)根系毒害的缓解效应,以水稻幼苗为实验材料,采用溶液培养方法,研究了50μmol·L-1镉胁迫下不同浓度镨对水稻幼苗根系鲜质量、形态和根系活力的影响。结果表明,50μmol·L-1镉胁迫下,水稻根系生长受到明显的抑制,根系鲜质量、根长、根表面积、根体积和根系活力明显降低,且随镉处理时间的延长,抑制程度加重。但镉对根系平均直径无明显影响。23～184μmol·L-1的镨对水稻镉毒害有一定的缓解效果,可不同程度的减轻镉对幼苗的伤害,促进了镉胁迫下根系鲜质量、根系长度、根系表面积和根系体积的增加,提高了根系活力,且随着处理时间的延长,缓解效应愈加明显,与单镉毒害相比,镨处理5天后根系鲜质量、根长、根表面积、根体积和根系活力分别提高了0.92%～14.8%、1.61%～16.3%、2.57%～20.3%、1.52%～17.2%和3.71%～32.8%,处理10d后根系鲜质量、根长、根表面积、根体积和根系活力分别提高了2.55%～31.2%、1.44%～21.4%、1.78%～27.2%、2.16%～23.4%和8.14%～52.9%;此外,23～184μmol·L-1的镨处理对直径≤1.0mm的根长和根表面积、直径0.5mmD≤1.0mm的根体积影响较大,其分别提高了0.9%～24.3%、1.9%～32.6%、0.4%～33.2%,其中以92μmol·L-1镨缓解效果最好。但随着镨浓度的进一步加大,当镨浓度达到230μmol·L-1时,反而会使水稻根系受到更严重的毒害。

Effects of praseodymium on root growth and morphological characteristics of rice seedlings under cadmium stress

Rare earth elements (REEs) have positive effects on the growth and development of plants and have been used as a fertil-izer additive for decades in China. In order to explore the ameliorating effects of praseodymium (Pr) on the toxicity of cadmium (Cd) to rice roots, root fresh weight, morphological characteristics and root activity of rice seedlings were studied with roots exposed to different Pr concentration and 50 μmol·L~(-1) Cd by hydroponic culture. The results showed that root growth was inhibited significantly by 50 μmol·L~(-1) Cd treatment. Fresh weight, total root length, root surface-area, root volume and root activity were decreased obvi-ously. And the inhibition becomes more serious with prolongation of treatment time. However, no marked change was noted for root average diameter. The inhibition of root fresh weight, root length, root surface-area, root volume and root activity were alleviated by the treatment of 23～184 μmol·L~(-1) Pr. And the alleviation of Pr on Cd toxicity was more evident with prolongation of treatment time. After 5 d' s Pr treatment, root fresh weight, root length, root surface-area, root volume and root activity increased by 0.92%～14.8%, 1.61%～16.3%, 2.57%～20.3%, 1.52%～17.2% and 3.71%～32.8%, respectively, and those increased by 2.55%～31.2%, 1.44%～21.4%, 1.78%～27.2%, 2.16%～23.4% and 8.14%～52.9%, respectively, after 10 d' s Pr treatment. Roots length and root surface-area with root diameter (D)≤1.0 mm and root volume with root diameter 0.5