Cd^(2+)胁迫下多年生黑麦草的生长与生理响应

Growth and Physiology Response of Perennial Ryegrass to Cd^(2+)Stress

为检验多年生黑麦草对重金属Cd2+的修复潜力,本文研究了多年生黑麦草对重金属Cd2+的积累特性和生长、生理响应,采用水培法对多年生黑麦草进行0、5、10、20mg·L-1重金属Cd2+胁迫,测定了地上部和地下部的生物量、Cd浓度。结果表明,处理6d后,多年生黑麦草的生长受Cd2+显著抑制,地下部、地上部的Cd2+浓度均随着处理浓度的增加而显著升高,多年生黑麦草对Cd2+具有超量积累能力。5mg·L-1Cd2+处理6d后,多年生黑麦草的地下部、地上部生物量和根冠比分别较对照显著下降了36.83%、12.17%和27.59%,叶片的净光合速率在5mg·L-1Cd2+处理6d后较对照显著下降了23.38%,而其他的气体交换参数、光合色素含量和PSⅡ最大、潜在光化学效率均未受到Cd2+的影响;当光合有效辐射超过580μmol·m-2·s-1时,5mg·L-1Cd2+处理下的实际光化学效率和相对电子传递速率均显著低于对照,Cd2+对多年生黑麦草光反应系统电子传递的抑制程度随着光合有效辐射的升高而增加;当辐射强度达到1 465μmol·m-2·s-1时,相对电子传递速率较对照显著下降了15.46%。5mg·L-1Cd2+胁迫下,多年生黑麦草叶片PSⅡ调节性能量耗散始终显著高于对照,减轻了过多激发能对光合机构的伤害。5mg·L-1Cd2+胁迫下,多年生黑麦草叶片和根系的超氧化物歧化酶、抗坏血酸过氧化物酶的活性被抑制,过氧化氢酶的活性被促进,丙二醛的含量显著提高。净光合速率、相对电子传递速率及SOD、APX活性可做为检验Cd2+对多年生黑麦草毒害的生理指标。本研究得到的结论可为在草坪草中选育重金属污染的修复植物提供参考。

In order to examine the phytoremediation potentiality of perennial ryegrass to heavy metal Cd2 ＋,the accumulation characteristics,growth and physiology response of perennial ryegrass to Cd2 ＋stress were illustrated in this paper. The plants were treated with 0,5,10,20 mg·L- 1Cd2 ＋solution for 6 days,when 6 days after treatment（ dat）,the growth of perennial ryegrass was significant inhibition by Cd2 ＋,Cd content of leaf and root were significantly elevated with increasing Cd2 ＋concentration,perennial ryegrass represented hyper-accumulative ability for Cd. When 6dat exposed to 5mg·L- 1Cd2 ＋,the root,shoot biomass and the ratio of root to shoot were significantly decreased by36. 83%,12. 17%,27. 59% compared with control. The net photosynthesis rate（ Pn） was significantly decreased by23. 38% compared with control when 6dat under 5 mg / L Cd2 ＋stress,whereas other gas exchange parameters,the photosynthetic pigment content and the maximum photochemical efficiency（ Fv / Fm）,potential photochemical efficiency（ Fv/ Fo） were not affected significantly. When photosynthetically active radiation（ PAR） exceeded 580μmol·m- 2·s- 1after 6 days treatment by 5 mg·L- 1Cd2 ＋concentration,the effective photochemical efficiency（ ΦPSII） and relative electrons transport rate（ r ETR） were lower than control,and the inhibition degree strengthened with the increasing PAR,when the PAR reached to the higest intensity（ 1 465μmol·m- 2·s- 1）,they were both significantly decreased by15. 46%.,whereas the regulatory energy dissipation [Y（ NPQ） ] was significantly higher than control all the time,this would alleviate the damage of photosynthetic agency induced by the excess excitation energy. When 6dat exposed to 5mg·L- 1Cd2 ＋concentration,the activity of superoxide dismutase（ SOD） and ascorbic acid peroxidase（ APX） were both inhibited,the activity of catalase（ CAT） was promoted,and the content of Malondialdehyde（ MDA） was significantly increased. The Pn,r ETR,and SOD,APX activity could be taken as the physiological indexes to indicate the impair extent of perennial ryegrass by Cd2 ＋. The conclusions of this study would provide reference for remedy plants breeding on the heavy metal pollution.