不同氮素水平对重金属胁迫下紫茎泽兰生长及重金属吸收的影响

以紫茎泽兰为对象,采用水培法研究无氮、低氮、中氮、高氮4个氮素水平对Pb、Zn、Cu、Cd等4种重金属胁迫条件下紫茎泽兰生长和重金属吸收的影响。结果表明:低氮水平下,紫茎泽兰多数生长参数显著高于其他试验组;中氮水平下,紫茎泽兰POD、CAT、可溶性蛋白、可溶性糖、脯胺酸和叶绿素含量显著较高。低氮水平有利于紫茎泽兰根、茎和叶器官对Pb、Zn和Cd的吸收,试验组紫茎泽兰根器官中Pb、Zn和Cd累积量显著高于茎和叶。说明紫茎泽兰对重金属胁迫具有一定的抗逆性,低氮、中氮水平提高了紫茎泽兰对重金属的耐受性和吸收能力。可考虑将紫茎泽兰用于重金属污染的生态修复。     

Autochthonous halotolerant plant growth-promoting rhizobacteria promote bacoside A yield of Bacopa monnieri (L.) Nash and phytoextraction of salt-affected soil

Phytoremediation is a promising approach for reclamation of salt-affected soil. Phytoextraction is the most commonly used process, which exploits plants to absorb, immobilize, and accumulate salt in their shoots. In this study, halotolerant plant growth-promoting rhizobacteria (PGPR) were isolated from the rhizosphere of wild grasses growing naturally in salt-affected areas of Lucknow, Uttar Pradesh (India) and were tested for their efficacies of salt-tolerance and plant growth-promoting (PGP) abilities. Based on 16S rRNA sequences, the most efficient halotolerant isolates possessing PGP traits were identified as Pseudomonas plecoglossicida (KM233646), Acinetobacter calcoaceticus (KM233647), Bacillus flexus (KM233648), and Bacillus safensis (KM233652). Application of these isolates as bio-inoculants significantly (P < 0.05) increased the growth and bacoside A yield of a medicinal plant, Bacopa monnieri (L.) Nash, grown on natural salt-affected soil. The phytoremediation of salt-affected soil was evident by the substantial increase in shoot Na⁺:K⁺ ratio of bio-inoculant-treated plants. When compared to un-inoculated control plants, the soil physico-chemical properties of bio-inoculant-treated plants were improved. The shoot and root biomass (fresh and dry weights), soil enzymes, and soil nutrient parameters showed significant positive correlations with the shoot Na⁺:K⁺ ratio. Consequently, the halotolerant PGPR screened in this study could be useful for the reclamation of saline soils concomitant with improved plant growth and bacoside A yield.     

单一及复合绿色螯合剂对苋菜镉、砷的富集影响研究

[目的]通过小区试验探究绿色螯合剂的复合施用在植物修复过程中的作用效果,以期为实际田间植物修复Cd、As污染土壤提供依据。[方法]在镉(Cd)、砷(As)污染菜地土壤中施加单一绿色螯合剂：3种小分子有机酸草酸(Oxalic acid, OA)、酒石酸(Tartaric acid, TA)、苹果酸(Malic acid, MA),2种氨基酸基螯合剂亚氨基二琥珀酸(Iminodisuccinic acid sodium salt, IDS)、聚天冬氨酸(Polyaspartic acid,PASP),并将小分子有机酸分别于与氨基酸基螯合剂进行复配,探究不同处理对田间苋菜(Amaranthus mangostanus L.)生长、重金属富集的影响。[结果]结果表明：PASP-MA、PASP-TA处理组产量显著高于对照组,其中PASP-MA处理组苋菜产量最高,为4.53 kg/m_²；苋菜不同组织的重金属累积差异显著,地下部分Cd、As积累量均高于地上部分(P＜0.05),但富集系数均低于1,未达到超富集植物特征；从苋菜对Cd、As的富集系数来看,仅有IDS-MA处理组对两种重金属的植物修复同时起到强化作用；7个复配处理组均能提高苋菜Cd转运系数,最高达到0.90,超出对照组51.3%；复配处理中IDS-OA、IDS-PASP处理组的苋菜As转运系数显著高于对照组,分别比对照组高出1.88、0.11倍。[结论]苋菜生物量大,生长周期短,添加IDS-MA可以同时提高苋菜对Cd、As两种重金属的富集量,可为广东Cd、As污染菜地植物修复提供理论依据。     

黑豆—油菜与大豆—油菜轮作模式土壤镉修复能力比较

通过设置黑豆-油菜、大豆-油菜的轮作模式在湖南醴陵进行大田试验,结果发现黑豆表现出较强的镉富集能力,其根、茎、叶及果壳中镉含量分别为2.14、2.63、4.10及1.34 mg/kg,富集系数均在1以上。油菜各个部位镉含量较高的分别为叶与茎,达到了7.13和4.73 mg/kg。黑豆各部位镉转运系数均高于大豆,各油料作物提取的重金属主要集中在茎与叶。大豆叶的镉富集系数为2.06,茎的镉富集系数为0.86,明显低于黑豆同部位的富集能力。每公顷土地经过一轮黑豆-油菜、大豆-油菜轮作分别能够从土壤中提取73.52 g和51.68 g的镉,对土壤重金属镉的修复效率约为3%。     

土壤中添加蚯蚓及秸秆对油菜积累镉的影响

采用盆栽试验,在不同镉(Cd)污染浓度的灰漠土中分别添加蚯蚓和新鲜秸秆,研究了添加蚯蚓和秸秆还田条件下油菜(Brassica rapa L.spp.Chinenesis)-土壤体系中Cd的分布情况.结果发现:(1)添蚯蚓可有效增加土壤中Cd向油菜体内转移;蚯蚓可以在Cd污染的土壤中生存,蚯蚓体内Cd浓度随土壤环境中Cd...     

红叶甜菜-花生和油葵-花生轮作修复土壤Cd的能力

利用生物量高的经济作物进行轮作，可在加快修复土壤Cd污染进程的同时获得一定的经济效益。本研究在长沙市望城区群力村Cd轻度污染的土壤进行冬季种植红叶甜菜、夏季复种植花生和春末种植油葵、夏季复种植花生的轮作模式试验，探究重金属修复潜力。结果表明：花生、油葵、红叶甜菜各部位Cd富集系数除花生果实外均大于1，对Cd均有较强的富集能力。油葵-花生、红叶甜菜-花生轮作模式种植一季可提取土壤Cd总量分别为40.80 g·hm^-2和53.34 g·hm^-2。红叶甜菜-花生轮作将土壤Cd含量由0.316 mg·kg^-1降至0.286 mg·kg^-1，油葵-花生轮作一季将土壤Cd含量由0.316 mg·kg^-1降至0.283 mg·kg^-1。研究表明，红叶甜菜-花生、油葵-花生轮作模式均对土壤重金属Cd有较好的修复潜力。     

重金属污染土壤几种生物修复方式比较

土壤重金属污染是全球普遍存在的问题,生物修复因其环境友好且成本效益高而得到广泛关注。但不同生物修复技术有其优势和局限性,充分了解每种修复技术的特点,才能更经济、有效地对污染土壤进行修复。本研究阐述对比了目前的土壤重金属生物修复方法,包括植物修复（植物挥发、植物固定和植物提取）、转基因植物提取、螯合辅助植物修复、微生物辅助植物修复等技术的机制、优势、局限性和适用性等方面的差异。综述提出有效的生物修复技术需要土壤化学、植物生物学、遗传学、微生物学和环境工程等多学科的有机结合。根据污染土壤的特点,结合具有相应改良特性的转基因植物,是实现污染土壤大面积修复的有效方法。同时,农艺措施对天然超级积累植物的生物量和重金属提取能力的刺激作用还需要进一步挖掘。植物修复可以与其他几种传统修复技术有效结合,利用转基因技术建立土壤+植物+微生物的组合是未来修复技术发展的最佳途径。     

重金属污染土壤不同修复处理后的土壤动物群落结构特征

为了探讨重金属污染过的土壤经修复后其土壤生态的变化情况,于2014.12—2015.12期间,采用干漏斗法针对经过不同修复处理后的土壤动物群落结构进行追踪研究。研究结果表明:由于污染抑制了某些土壤动物的生存,导致土壤动物的个体数与类群数锐减;而杜绝污染水源后,修复植物根系土壤动物群类群数与个体数增加,并且蜱螨目、弹尾目和线虫纲等常见的土壤动物类群修复效果明显。说明被重金属污染过的土壤在断绝污染水源后,人工种植修复植物不仅可以改善土壤物理性质,而且对根系土壤动物也有修复作用。     

3种浮床植物对关中地区2种污染源涝池水体净化效率研究

基于对植物修复空间特异性的理解,针对联通关中水系的涝池近年来出现的水体富营养化和黑臭现象,选取常见浮床植物美人蕉、水菖蒲和西伯利亚鸢尾,通过室外水培试验,探究其对涝池污染原水的净化效果,试验共持续35天。结果表明:(1)试验结束时,3种植物在株高、根长生物量均有显著增加,增长率表现为美人蕉水菖蒲西伯利亚鸢尾。(2)美人蕉、水菖蒲和西伯利亚鸢尾对水体中TN的平均去除率分别为56.18%,52.17%,60.76%,均显著高于对照组(P0.05);美人蕉和水菖蒲对水体中TP平均去除率分别为55.42%和58.32%,均显著高于对照组(P0.05),而西伯利亚鸢尾组与对照组无显著差异(P0.05),此外美人蕉和水菖蒲还能起到调节水体pH和DO的作用。(3)3种植物对水体中NH_3—N的平均去除率分别为76.98%,65.71%,78.94%,其中美人蕉组和水菖蒲组NH_3—N的主要去除途径为植物吸收和硝化反应,西伯利亚鸢尾组NH_3—N的主要去除途径主要是氨的挥发和硝化反应等,而对照组NH_3—N去除率高达60.55%的主要原因是氨的挥发;植物组及对照组中NO_3~-—N浓度随时间均呈现增加趋势,主要与各试验组中水体硝化反应及植物吸收效率的差异性有关。(4)3种植物中,水菖蒲适用于点源和面源2种污染源涝池水体的净化,美人蕉只适合用于面源污染涝池水体的净化,而西伯利亚鸢尾净化能力较差,生长适应性差,不适宜作为水生浮床植物推广。研究结果为涝池污染水体修复的浮床植物选择提供参考。     

Mechanisms of cadmium accumulation in rice grains and molecular breeding for its reduction

ABSTRACT

Cadmium (Cd) has an important impact on agriculture, as the excessive consumption of this element from contaminated food crops leads to toxicity in humans. Rice is the greatest source of dietary Cd intake in populations consuming rice as a staple food. Therefore, reducing the Cd concentration of rice grains for diminishing the potential risk of Cd for human health is a major challenge. This review summarizes the main achievements on Cd accumulation in rice by our research group. Using a positron-emitting tracer imaging system, we succeeded to visualize differences in real-time Cd dynamics from roots to panicles in rice varieties with different Cd accumulation abilities. Several loci or genes responsible for Cd accumulation in rice were found through quantitative trait loci (QTLs) analysis. Using the QTL qCdp7 responsible for efficiently extracting Cd from paddy soils, practical rice varieties for Cd-phytoextraction were developed by DNA marker-assisted breeding. A rice variety named ‘Koshihikari Kan No.1? carrying a mutant allele of OsNramp5 for reducing Cd concentration in rice grains was produced by mutant breeding with ion-beams, and breeding programs have been implemented to transfer this allele into many Japanese rice varieties by DNA marker-assisted breeding. Growing low-Cd varieties aerobically would be a feasible way to simultaneously reduce inorganic arsenic and Cd concentrations in rice grains. These results provide basis for reducing Cd concentration in rice through breeding new varieties.