镉胁迫下锌硒交互作用对水稻镉毒害的缓解机制

Alleviation Mechanisms of Zinc-selenium Interaction on the Cadmium Toxicity in Rice Under Cadmium Stress

研究镉、锌、硒及不同组合复合添加对水稻种子萌发、植株生长发育和不同部位镉含量的影响,揭示锌、硒、锌硒交互作用对水稻镉毒害的缓解机制。以水稻品种南粳9108为研究对象,采用萌发试验和水培试验,测定其萌发、生长、生理指标及不同部位镉含量。结果表明:不同镉浓度水平胁迫下,种子萌发表现为低促高抑,添加锌后可以缓解镉对种子生理指标的抑制作用,减少镉含量的积累,添加硒则不能缓解种子生理指标的抑制作用,且高硒会加重毒害使种子生理指标值降低,锌硒联用可以促进种子萌发,但不能促进幼根幼芽生长;在5 mg/L镉胁迫下,添加不同浓度硒、锌均能显著增加水稻幼苗的根长、株高、叶片相对含水量、SPAD值,缓解镉对水稻生长发育的毒害,显著降低水稻根系镉含量;但锌硒联用会使水稻株高、SPAD值显著降低,而对水稻根长、叶片相对含水量的影响不显著。可见,镉胁迫下添加适宜浓度的锌、硒可以有效降低镉在水稻中的积累,缓解镉对水稻生长发育的毒害作用。

This work aims to study cadmium Cd,zinc(Zn),selenium(Se)and various combinations of them on the germination of rice seeds,growth and development of plants,and the Cd contents in different parts,as well as to explore the alleviation mechanisms of Zn or Se or Zn-Se interaction on the toxicity of Cd in rice.Having rice variety Nanjing 9108 as study object,germination and hydroponic experiment were conducted to measure the germination,growth,physiological indexes and Cd content in different parts.The experimental results showed that seed germination was promoted at low concentration of Cd,while inhibited at high concentration.The inhibitory effects of Cd on the physiological indexes of rice seeds were alleviated after Zn added,and accumulation of Cd was reduced.Instead,the inhibitory effects of Cd on the physiological indexes of rice seeds were not alleviated after Se added,and high concentration of Se increased the toxicity of Cd on the seeds and led to the physiological indexes of seeds reduced.The synergistic application of Zn and Se promoted seed germination,but did not facilitate the growth of rice seedlings.Under 5 mg/L Cd stress,adding Zn or Se at different concentrations both significantly increased the lengths of roots,the heights of seedlings,relative water contents of leaves and the value of SPAD,alleviated the toxicity of Cd to rice growth and development,as well as significantly reduced Cd contents in the roots of rice.The heights of seedlings and SPAD decreased dramatically,and lengths of roots and relative water contents did not change observably after Zn and Se were added together.Therefore,appropriate concentration of Zn and Se may effectively decrease the Cd accumulation in rice,and reduce the toxicity of Cd to rice.