外源褪黑素对镉胁迫下豌豆种子萌发、幼苗抗性生理及镉含量的影响

为探究外源褪黑素(MT)对镉胁迫下豌豆种子萌发和幼苗生长影响的生理机制,以豌豆品种中豌6号为试验材料,采用培养皿滤纸法,研究不同浓度外源褪黑素(0、50、100、200、400 μmol·L^-1)对镉胁迫(0、10、100 μmol·L^-1)下豌豆种子萌发、幼苗生长及生理指标的影响。结果表明,镉胁迫显著抑制了豌豆种子萌发及幼苗生长;施用外源褪黑素能够显著提高镉胁迫下豌豆种子的发芽势和发芽率,促进豌豆幼芽和幼根的生长,提高豌豆幼芽的超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性,并降低丙二醛(MDA)和镉含量。当Cd²⁺浓度为10 μmol·L^-1时,施用100 μmol·L^-1 MT较未添加MT豌豆的发芽势、发芽率、芽长、根长、芽鲜重和根鲜重分别增加90.47%、82.94%、127.27%、129.47%、131.71%和83.33%,SOD、POD和CAT活性分别提高24.17%、40.50%和76.91%,MDA含量下降57.64%,镉含量下降57.62%。结果表明,适宜浓度的外源褪黑素能够通过提高抗氧化酶活性,降低活性氧的积累,抑制豌豆幼苗对镉的吸收,从而缓解镉胁迫对豌豆幼苗的毒害作用,促进种子萌发及幼苗生长。本研究结果为进一步探索外源褪黑素缓解豌豆镉胁迫的机理提供了一定的理论依据。

Effects of Exogenous Melatonin on Seed Germination,Seedling Resistance Physiological and Cd Content of Pea Under Cadmium Stress

To explore the physiological mechanism of exogenous melatonin (MT) on seed germination and seedling growth of pea under cadmium (Cd) stress, the pea (Pisum sativum cv. Zhongwan No 6) was used as experimental material, and different concentrations of exogenous MT (0, 50, 100, 200, 400 μmol·L^-1) were studied by using culture dish filter paper method under Cd stress (0, 10, 100 μmol·L^-1). The results showed that Cd stress significantly inhibited the seed germination and seedling growth of pea, whereas applying exogenous melatonin could remarkably improve pea seed germination potential and germination percentage, promote the growth of plumule and radicle, and enhance the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), and reduce malondialdehyde (MDA) content and Cd uptake of pea seedlings under Cd stress. When the concentration of Cd2+ was 10 μmol·L^-1, compared with the treatment without MT, the germination potential, germination rate, bud length, root length, bud fresh weight, root fresh weight, SOD, POD and CAT activities of peas increased by 90.47%. 82.94%, 127.27%, 129.47%, 131.71%, 83.33%, 24.17%, 40.50% and 76.91%, respectively, and the content of MDA and Cd decreased by 57.64% and 57.62%, respectively. The results indicated that MT application at the appropriate concentration had the positive effects on alleviating toxic effect of Cd and promoting seed germination and seedling of pea by enhancing the activity of antioxidant enzymes, reducing the accumulation of reactive oxygen and inhibiting the uptake of Cd by pea seedlings. The results of this study provide a theoretical basis for further exploring the resistance mechanism of MT to alleviate Cd stress in peas.