锰污染土壤对酸模叶蓼氮素代谢的影响

摘要

探讨超富集植物高浓度金属富集量对其生理机制的影响,对于了解超富集植物强大的解毒机制与其生理机制的相关性有重要意义.采用室内原矿土栽培的方法,研究了贺州某锰矿区未开采区(T2)、探矿区(T3)、恢复区(T4)、开采区(T5)、尾矿库(T6)土壤及桂林未受污染的菜园土(T1)对锰超富集植物酸模叶蓼(Polygonum lapathifolium L.)生长,锰吸收,叶片铵态氮、硝态氮、游离脯氨酸、可溶性蛋白质含量及氮素代谢关键酶(硝酸还原酶NR)、谷氨酰胺合成酶GS、谷氨酸合酶GOGAT和谷氨酸脱氢酶GDH)活性的影响.结果表明,随着Mn处理浓度的提高,酸模叶蓼根、茎、叶中Mn含量显著增加(P<0.05),叶绿素a、叶绿素b和总叶绿素在T3处理时含量最高,此时分别为对照的1.15、1.23和1.17倍,但所有锰处理下酸模叶蓼生物量无显著性差异(P>0.05).Mn处理一定程度上提高了叶片中可溶性蛋白质含量,引起了酸模叶蓼氮素代谢关键酶活性的变化及硝态氮、铵态氮和脯氨酸含量的显著增加(P<0.05).T6处理硝态氮、铵态氮和脯氨酸含量最高,分别比对照提高了17.6%、43.8%和206.2%.NR、GS和GOGAT活性呈先增加后降低的变化趋势,NR、GS和GOGAT活性分别在T2、T3、T4处理时最高,此时分别比对照提高了6.4%、28.8%和66.4%.GDH活性则随着Mn处理浓度的增加而增加,在T6处理时活性最高,比对照提高了1.74倍.以上表明,GDH在解毒Mn毒害过程中具有重要作用.%To reveal the relationship between detoxification mechanism and physiology of the metal hyperaccumulator plants, an incubation experiment with intact soil was conducted to investigate the effects of Mn on the growth, metal accumulation and nitrogen metabolism in the manganese hyperaccumulator plant Polygonum lapathifolium L. The soils were collected from unmined (T2), mine-prospection (T3), recovery (T4), mining (T5) and tailing (T6) areas and an unpolluted soil from vegetable garden in Guilin (T1) was used as a comparison. The ammonium nitrogen, nitrate nitrogen, soluble proteins, free proline in leaves as well as the enzymatic activities of nitrogen metabolism including Nitrate Reducatse (NR), Glutamine Synthelase (GS), Glutamate Synthase (GOGAT), Glutamate Dehydrogenase (GDH), were determined. The results indicated that Mn contents increased significantly (P<0.05) in the tissues of plants with the increased concentrations of Mn in the treatments. The contents of chlorophyll a, chlorophyll b and the total chlorophyll ofP. lapathifolium reached maximum in the T3 treatment, which were 1.15, 1.23 and 1.17 times to the control, respectively. However, the biomass did not show significant increase (P>0.05). The content of soluble proteins was also promoted as compared to the control, but not significantly (P>0.05). Significant (P>0.05) increase was found in the contents of ammonium nitrogen, nitrate nitrogen and free proline under treatment with the contaminated Mn soils; with maximum values occurred in the T6 treatment, in which these parameters were promoted by 17.6%, 43.8% and 206.2% compared to the control, respectively. The activities of NR, GS and GOGAT increased first, and then decreased with the increasing of Mn contents in the soil. The activities of NR, GS and GOGAT peaked in the treatments of T2, T3 and T4 with 6.4%, 28.8% and 66.4% increase compared to the control, respectively. At the same time, the activity of GDH increased significantly (P<0.05) with the increase of Mn contents in the soil, with the value 1.74 times of the control. The results explicate that Mn contaminated soil could induce the changes of nitrogen metabolism ofPolygonum lapathifolium.