油菜对土壤重金属Cd抗性的研究进展

近年来,由于矿产开发与冶炼、化肥和农药的施用以及污水灌溉,导致重金属镉污染日益加剧。重金属镉毒性很强,不仅影响植物的生长,还可以通过食物链,危害动物和人体健康,是重金属污染中最危险的污染物之一。据有关研究,油菜对镉有较高的吸收性和较强的耐受性,具备一定的土壤镉污染的修复潜力。笔者综述大量的前人研究成果,从镉在油菜中的吸收、运输、积累及再分布、镉胁迫对油菜生长发育的影响、以及油菜的耐镉机制3个方面论述了重金属镉对油菜的影响及油菜对镉的抗御及耐受机制,为镉污染农田油菜高效种植及油菜高效吸镉提供理论支持。     

甘蓝型油菜在镉污染土壤修复中的应用研究

中国南方土壤镉污染现象较为严重,对中国农业发展及农产品安全带来很大影响。植物修复是解决镉污染农田一个发展前景较好的方法,但缺少合适的修复植物。在本研究中,以长江中下游地区大面积种植的经济作物——甘蓝型油菜为对象,利用盆栽的方式,研究0、5、15、25 mg/kg 4个浓度梯度下,镉超标对油菜生长、菜油品质的影响。结果发现,镉超标对油菜生长有一定影响,但菜油中镉含量远低于国际标准要求,表明产自镉污染土壤的菜籽油并不影响其食用价值。且利用油菜作为修复植物,还可增加当地农民收益和中国菜油供应,缓解日益严重的食用油供给不足现状,因此油菜是一种较为理想的镉污染土壤修复植物。     

铅镉复合污染对土壤和水稻叶片生理生化特性的影响

采用盆栽试验,研究了不同程度的铅镉复合污染对水稻叶片生理生化特性的影响。结果表明,铅镉污染导致土壤pH显著降低;玉香油占(Y)在低浓度污染下有机质显著下降,然后随着重金属污染程度升高。天优998（T）在低浓度污染下有机质变化不明显,然后显著降低;除了玉香油占在分蘖期低浓度下SPAD有显著增加,铅镉胁迫显著降低了叶片SPAD值,天优998分蘖期在高浓度下SPAD值显著下降,孕穗期SPAD随重金属污染程度增加而显著增加,灌浆结实期SPAD随重金属污染程度增加而显著降低;水稻叶片抗氧化酶活性在低度铅镉胁迫下活性增加,高度胁迫下活性下降,POD对铅镉胁迫比SOD具有较强的敏感性;MDA含量与铅镉污染程度成正相关。     

在铀尾渣污染土中壤添加磷对植物生长及积累重金属的影响

在重金属污染土壤中添加化学稳定剂,可降低重金属的生物有效性,阻控重金属进入食物链。设计盆栽试验,在铀尾渣污染土壤中添加不同浓度的磷肥(0、30、60、120、240和480 mg kg^-1),调查磷对芥菜型油菜(Brassica juncea)和甘蓝型油菜(B. napus)的生长及植株积累重金属铀、镉、锌和铅含量的状况,分析添加磷肥前后植株内磷含量和土壤重金属DTPA提取态含量的变化。结果表明,添加磷肥前,铀尾渣污染土壤总氮、总磷、总钾和有机质的含量低,铀、镉、锌和铅的含量高,对两种油菜的生长有抑制作用;添加磷肥后,两种油菜体内磷含量增加,污染土壤中的铀、镉、锌和铅的DTPA提取态含量显著降低,其降幅分别为17.1%~70.5%、24.0%~57.6%、8.9%~32.4%和8.6%~55.8%;大幅度降低两种油菜体内的铀、镉、锌和铅含量,其含量与土壤中这些重金属DTPA提取态含量显著正相关;显著增加两种油菜的干重、株高、根长和叶绿素含量,显著降低其体内的SOD活性和MDA含量。因此在铀尾渣污染土壤中添加磷可有效减少重金属在油菜体内积累,降低重金属沿食物链传递的风险。     

有机酸、EDTA对镉污染土壤上稻米品质的影响

为了寻求有效抑制污染土壤上水稻对重金属Cd的吸收、保持稻米卫生品质的技术方法,通过采用污染土壤盆栽实验,研究了有机酸、EDTA对镉污染土壤上不同基因型水稻稻米品质的影响,结果表明：随着镉污染浓度的增加,糙米中镉含量显著增加,直链淀粉、蛋白质、粗脂肪的含量降低。开花期施加外源有机酸、EDTA,镉污染水稻糙米中镉含量均不同程度下降。以EDTA降低籽粒镉的含量幅度最大,其次是有机酸+1/2EDTA,有机酸作用较弱。外源有机酸、EDTA同时提高了镉污染水稻籽粒蛋白质的含量,EDTA > 有机酸、有机酸+1/2EDTA,但不同程度降低了水稻籽粒中直链淀粉、粗脂肪的含量,以EDTA降低幅度较大。就稻米品质而言,在镉污染土壤上,以有机酸+1/2EDTA对于水稻品质效果优于EDTA、有机酸。在镉污染土壤上种植常规水稻品种‘Ⅱ优527’较高镉积累型品种‘秀水63’更易获得高产优质稻米。     

植物对重金属镉的吸收与耐受机制研究进展

为了有效降低土壤中镉含量，保障人类健康，人们希望通过一种经济、有效的方法——植物修复技术来治理土壤镉污染。因此，植物对重金属镉的吸收与耐受机制研究，已成为近年来植物逆境生理研究的热点。笔者主要综述了植物对镉的吸收、转运及积累机制，以及植物体通过细胞壁的沉积、细胞区室化、螯合作用和抗氧化系统的保护作用对镉的耐受机制，以期为今后通过植物修复技术更好治理土壤镉污染提供基础资料。     

在铀尾渣污染土壤中添加磷对植物生长及重金属积累的影响

在重金属污染土壤中添加化学稳定剂,可降低重金属的生物有效性,阻控重金属进入食物链。设计盆栽试验,在铀尾渣污染土壤中添加不同浓度的磷肥(0、30、60、120、240和480mgkg-1),调查磷对芥菜型油菜(Brassica juncea)和甘蓝型油菜(B.napus)的生长及植株积累重金属铀、镉、锌和铅的状况,分析添加磷肥前后植株内磷含量和土壤重金属DTPA提取态含量的变化。结果表明,添加磷肥前,铀尾渣污染土壤总氮、总磷、总钾和有机质的含量低,铀、镉、锌和铅的含量高,对两种油菜的生长有抑制作用;添加磷肥后,两种油菜体内磷含量增加,污染土壤中的铀、镉、锌和铅的DTPA提取态含量显著降低,其降幅分别为17.1%～70.5%、24.0%～57.6%、8.9%～32.4%和8.6%～55.8%;大幅度降低两种油菜体内的铀、镉、锌和铅含量,其含量与土壤中这些重金属DTPA提取态含量显著正相关;显著增加两种油菜的干重、株高、根长和叶绿素含量,显著降低其体内的SOD活性和MDA含量。因此在铀尾渣污染土壤中添加磷可有效减少重金属在油菜体内积累,降低重金属沿食物链传递的风险。     

不同类型高粱对重金属镉吸收积累的动态变化

为了探寻利用高粱修复镉污染土壤的可行性和有效方法,为快速高效修复土壤重金属污染提供理论依据和经验,本研究在湖南农业大学浏阳市综合教学实验基地和湘阴农科所2个环境下分析了4个高粱品种在5个生育期间植株中镉吸收积累特性和动态变化。方差分析表明成熟期高粱根部的镉含量和镉积累量主要受土壤的影响,品种间差异较小;地上部分镉含量和镉积累量在品种间达到极显著水平。4个高粱品种苗期地上和根系部分的镉含量分别为3.75 mg/kg和7.60 mg/kg,都显著高于其它生长阶段。高粱地上部分镉积累量在抽穗期达到最高值,2个生物质高粱地上部分镉积累量都超过65 g/hm2,是甜高粱的2～4倍。但成熟期4个品种地上部分镉积累量为23.35～33.39 g/hm2,差异较小。上述研究显示,通过筛选镉积累量高的生物质高粱品种并适时收获,同时提高高粱复种指数对有效、快速修复镉污染土壤具有积极意义。     

叶面调理剂在不同镉污染程度稻田应用效果研究

探讨3种叶面调理剂对不同镉污染程度稻田土壤中全镉含量、有效态镉含量、土壤pH、稻米镉含量、水稻各个组织中镉含量以及产量的影响。选用硅钾中量元素肥料、碧护营养套餐和降镉灵3种叶面调理剂,分别在长沙县金井镇、黄花镇和望城区茶亭镇受重金属镉污染水稻田开展大田控镉试验。结果表明：喷施叶面调理剂水稻产量得到显著提高;叶面调理剂对土壤中全镉含量影响不显著,但能显著降低土壤有效态镉含量;叶面调理剂能小幅提高土壤pH,但在不同地区表现差异较大;叶面调理剂能降低糙米镉含量,但在镉中度污染稻田,不能降低糙米镉含量到国家限量标准(≤0.2 mg/kg)。施用碧护营养套餐可增加水稻产量,提高土壤pH,降低土壤有效态镉含量,降低糙米镉含量,建议在轻微、轻度镉污染程度稻田进一步示范推广。     

湖南典型酸性镉污染稻田全过程管控技术案例研究

长沙县试验稻田属于南方典型的酸性镉污染稻田，水稻对土壤中镉的富集程度较高[1]，镉大米的生产将对食品安全和人类健康产生风险。本文对选取的镉污染稻田其进行了污染特征分析及污染风险评价，然后根据分析评价结果采用全过程管控模式（前端灌溉水净化，中端稳定化控制，末端植物富集）开展了修复治理研究。结果表明：该试验稻田案例地属于高风险，采用全过程管控模式后，稻米镉下降67.24%；土壤有效态镉下降38.10%，水稻增产8.85%。土壤总镉的去除率达3.17%~8.45%，油菜植株对土壤总镉的富集系数为2.69~3.43。通过估算，本案例地直接治理成本为每季5100元/hm2。本研究对污染稻田修复建立起一套完整的全过程管控集成技术并进行推广及示范有重要意义。     

Biological Activity and Quantification of Suspected Allelochemicals from Alfalfa Plant Parts

Autotoxicity restricts reseeding of alfalfa (Medicago sativa L.) after alfalfa until autotoxic chemical(s) breaks down or is dispersed into external environments. A series of aqueous extracts from leaves, stems, roots and seeds of alfalfa ‘Vernal’ were bioassayed against alfalfa seedlings of the same cultivar to determine their autotoxicity. The highest inhibition was found in the extracts from the leaves. Extracts at 40 g dry tissue l^?1 from alfalfa leaves were 15.4, 17.5 and 28.7 times more toxic to alfalfa root growth than were those from roots, stems and seeds, respectively. A high‐performance liquid chromatography (HPLC) analysis with nine standard compounds showed that the concentrations and compositions of allelopathic compounds depended on the plant parts. In leaf extracts that showed the most inhibitory effect on root growth, the highest amounts of allelochemicals were detected. Among nine phenolic compounds assayed for their phytotoxicity on root growth of alfalfa, coumarin, trans‐cinnamic acid and o‐coumaric acid at 10^?3 m were most inhibitory. The type and amount of causative allelochemicals found in alfalfa plant parts were highly correlated with the results of the bioassay, indicating that the autotoxic effects of alfalfa plant parts significantly differed.     

Changes in Seed Yield and Quality with Maturity in Onion (Allium cepa L., cv. 'Early Cream Gold')

Development of onion (Allium cepa L., cv. ‘Early Cream Gold’) seed under cool climate conditions in Tasmania, Australia occurred over a longer duration than previously reported, but similar patterns of change in yield components were recorded. In contrast to previous studies, umbel moisture content declined from 85 to 67 % over 57 days while seed moisture content decreased from 85 to 31 %. Seed yield continued to increase over the duration of crop development, with increasing seed weight compensating for seed loss resulting from capsule dehiscence in the later stages of maturation. Germination percentage was high and did not vary significantly from 53 to 77 days after full bloom (DAF), but mean germination time declined and uniformity of germination increased significantly over the same time period. The percentage abnormal seedlings declined with later harvest date, resulting in highest seed quality at 77 DAF. The results of this study suggest that the decision to harvest cool climate onion seed crops before capsule dehiscence will result in a loss of potential seed yield and quality.     

Location of a high-lysine gene and the DDT-resistance gene on barley chromosome 7

Summary The high-lysine gene in Risø mutant 1508 conditions an increased lysine content in the endosperm via a changed protein composition, a decreased seed size, and several other characters of the seed. The designation lys3a, lys3b, and lys3c, is proposed for the allelic high-lysine genes in three Risø mutants, nos 1508, 18, and 19. Linkage studies with translocations locate the lys3 locus in the centromere region of chromosome 7. A linkage study involving the loci lys3 and ddt (resistance to DDT) together with the marker loci fs (fragile stem), s (short rachilla hairs), and r (smooth awn) show that the order of the five loci on chromosome 7 from the long to the short chromosome arm is r, s, fs, lys3, ddt. The distance from locus r to locus ddt is about 100 centimorgans.     

A note on the origin of Kalanchoë x vadensis Boom & Zeilinga (Crassulaceae)

Summary K x vadensis is a hybrid of K. blossfeldiana and K. marmorata obtained after doubling the number of chromosomes.     

Simultaneous Determination of Four Phenolic Acids in Radix Salviae Miltiorrhizae Formula Granules by QAMS

[Objectives]This study aimed to establish a QAMS(quantitative analysis of multi-components by single-marker)method for simultaneous determination of four phenol...     

Avoidance of leaf rust fungi in wild relatives of cultivated cereals

Summary Avoidance of rust fungi that was based on poor appressorium induction was previously found in Hordeum chilense. In the present study 95 accessions of Triticeae were screened for avoidance of Puccinia hordei. The percentage of appressorium formation per germinated spore ranged from 6 to 90%. On none of the 41 accessions of Aegilops, Agropyron, Elymus, Secale, Thinopyrum or Triticum studied was the rate of appressorium formation lower than 25%. Lower rates of appressorium formation were, however, found on accessions of wild barley species Hordeum brachyantherum, H. marinum, H. parodii and H. secalinum. Its implications in cereal breeding are discussed.     

Variation in forage grasses as hosts of the root-knot nematode Meloidogyne naasi (Franklin) and selection for resistance in ryegrass

Summary Reactions of 13 grasses to Meloidogyne naasi varied with species; ryegrasses, fescues and their hybrids were generally susceptible and cocksfoot and timothy resistant. Marked variation in host resistance levels occurred between genotypes within cultivars.Selection of single plants, followed by tests on replicate tillers, identified resistant and susceptible genotypes in both Italian and perennial ryegrass cultivars. Resistant plants had few nematode-induced galls and fewer females and eggs than susceptibles. There was more or less continuous variation, with many genotypes intermediate between extremes of resistance and susceptibility. Selected resistant and susceptible genotypes are of use in assessing variation in nematode populations and as controls for breeding and selection programmes.     

Current and future strategies in breeding lentil for resistance to biotic and abiotic stresses

Lentil production is limited by lack of moisture and unfavorable temperatures throughout its distribution. Waterlogging and salinity are only locally important. Progress has been made in breeding for tolerance to drought through selection for an appropriate phenology and increased water use efficiency and in breeding for winter hardiness through selection for cold tolerance.The diseases rust, vascular wilt, and Ascochyta blight, caused by Uromyces viciae-fabae, Fusarium oxysporum f. sp. lentis, and Ascochyta fabae f. sp. lentis, respectively, are the key fungal pathogens of lentil. Cultivars with resistance to rust and Ascochyta blight have been released in several countries and resistant sources to vascular wilt are being exploited. Sources of resistance to several other fungal and viral diseases of regional importance are known. In contrast, although the pea leaf weevil (Sitona spp.) and the parasitic weed broomrape (Orobanche spp.), and to a lesser extent the cyst nematode (Heterodera ciceri), are significant yield reducers of lentil, no sources of resistance to these biotic stresses have been found. Directions for future research in lentil on both biotic and abiotic stresses are discussed.     

Present status and future strategy in breeding faba beans (Vicia Faba L.) for resistance to biotic and abiotic stresses

Progress is being made, mainly by ICARDA but also elsewhere, in breeding for resistance to Botrytis, AScochyta, Uromyces, and Orobanche; and some lines have resistance to more than one pathogen. The strategy is to extend multiple resistance but also to seek new and durable forms of resistance. Internationally coordinated programs are needed to maintain the momentum of this work.Tolerance of abiotic stresses leads to types suited to dry or cold environments rather than broad adaptability, but in this cross-pollinated species, the more hybrid vigor expressed by a cultivar, the more it is likely to tolerate various stresses.     

Water Extraction Process of Chinese Herbal Compound Man Gan Ning

[Objectives]To optimize the water extraction process of Chinese Herbal Compound Man Gan Ning and establish a method for its extraction and content determination...