White clover clones as a cost-effective indicator of phytotoxic ozone: 10 years of experience from central Italy

Data collected at one site in central Italy using the NC-S/NC-R clover (Trifolium repens) biotype system during 1997-2007 were analysed in order to assess: (a) its performance under Mediterranean conditions; (b) variations of ozone damage linked with meteorological conditions; (c) if critical level approach is a good predictor of ozone risk on vegetation. NC-S dry biomasses were systematically lower than those of NC-R, the mean ratio being 0.7. Relevant relationship between ozone visible injury and cumulated values of AOT40 were also reported. Temperature and number of rainy days were the most important factors associated with ozone presence and, as a consequence, with leaf injury index. Photosynthetic gas exchange properties indicate that NC-S has higher values of stomatal conductance.     

Interaction between water soluble and volatile compounds of Cistus ladanifer L.

Summary. Phytotoxic activity of single and combined application of water soluble and volatile compounds of Cistus ladanifer on germination and early root growth of subterranean clover was investigated. Total germination, lag and speed of germination were both inhibited and stimulated, with the activity of volatiles on total germination depending upon the presence of water solubles. Antagonism between water solubles and volatiles was always found, resulting in a reduction of inhibition or a shift from inhibition to stimulation. It is suggested that the simultaneous presence of water solubles and volatiles might result in changes of the chemical nature of metabolites released by C. ladanifer. Early root growth was always inhibited but only by water solubles, and no interaction was found. The ecological implications of these results are discussed in terms of the exhaustion of competitors seedbanks by a two-step process in which germination is less inhibited or even stimulated by water solubles and volatiles, followed by a stronger and volatiles-independent inhibition of early root growth. Received 13 June 2001; accepted 13 Dezember 2001.     

不同AM真菌对三叶草耐油性的影响

在盆栽条件下研究了4个油浓度（0、5000、10000和50000w/mgkg^-1）下接种辽河油田污染土壤中分离出的3种AM真菌（Glomus mosseae，G.geospora，G.constrictum）对三叶草耐油性的影响。试验结果表明：1）随着油浓度的增加，侵染率亦增加，10000mgkg^-1时G.geospora和G.constrictum的侵染率分别为67.65％和82.86％；2）从侵染率、地上部生物量和菌根依赖性来看，随着油浓度的增加，最适的AM真菌亦不一样，油浓度为0、5000和10000mgkg^-1时，最适AM真菌分别是G.geospora、G.mosseae和G.constrictum；3）油污染土壤上接种AM真菌能促进植株的地下部和地上部的生长，接菌处理的茎干重比相应的对照增加62.2％-267.1％；4）随着油浓度的增加和植物的生育进程，AM真菌的接种效应在增强。图3表3参14     

果园间种白三叶草对土壤生态及果树生产的影响

针对我国果园长期沿用清耕除草方式所带来的水土流失、土壤肥力下降和果品品质变劣等问题,于1999年在山东省烟台市5个试验点分别设置了由种草样地及其清耕对照样地组成的5组可比样地,对苹果园间种白三叶草(Trifoliumrepens)对土壤生态和果树生产的影响进行定位观测。结果表明:果园种草3a后0—30cm土层有机质含量平均提高3. 3g·kg-1,氮、磷、钾等养分含量有较大提高,尤以表层土壤更明显;土壤含水量得到提高,尤以夏秋多雨季节更明显;种草果园地下5cm处土温夏季比对照平均降低4. 1℃,而冬季升高2. 5℃,使土温的全年变化较为缓和;种草果园果品产量平均增加7. 04%,年产牧草2 130kg·hm-2,每年可增加经济收入5 328元·hm-2。     

Biologically active secondary metabolites in white clover (Trifolium repens L.) – a review focusing on contents in the plant, plant–pest interactions and transformation

Summary.  To exploit biologically active compounds from white clover (Trifolium repens L.) for suppressing weeds and soil-borne diseases, either as isolated products (biopesticides) or through cultivars with enhanced production of these compounds, the biologically active compounds must be identified, plant content measured, and their fate in soil known. The present review summarizes the published knowledge needed for such exploitation; providing essential information on structure and concentration of flavonols, flavones, condensed tannins, isoflavones, isoflavanones, pterocarpans, coumestans, cyanogenic glucosides, and saponins in healthy and stressed white clover plants. Various stresses and particular cultivars affect the concentrations of several of the compounds. Information on biological effects and the degradation/transformation of these compounds in plants or by microorganisms is available. There is no information on the degradation pathway in soil, the mechanisms of exudation and leaching of compounds from plants, and soil sorption properties of the compounds. The clover soil fatigue problem is increasing in grasslands and causes problems especially in organic farming. Research efforts focused on biological elements of clover soil fatigue have not explained it, and the influence of secondary metabolites has not been investigated. There are few investigations into the interaction between beneficial fungi/fungal-diseases and the occurrence of biologically active secondary metabolites in white clover plants. Such studies are critical to better understand beneficial fungi and pathogens.     

钙和钙离子通道阻断剂对丛枝菌根真菌吸收镉的影响

本试验以三叶草(Trifolium repense L.)为宿主植物,Glomusintra radices为供试菌种,通过分室系统将外生菌丝与植物根系分隔开,并对菌丝室加以不同含量水平的Ca2+、Cd2+和Ca2+通道阻断剂(Verapamil、LaCl3)进行处理,研究在菌丝吸收过程中Cd2+与Ca2+以及Ca2+通道之间的关系.试验结果表明,高Cd2+和LaCl3处理可促进菌丝发育;高Cd2+和Verapamil、LaCl3处理不同程度地降低了菌丝对Ca2+的吸收;高Ca2+和LaCl3处理则可提高菌丝对Cd2+的吸收.根据本试验结果可以认为,Cd2+在菌丝上的跨膜转运不是通过Ca2+通道完成,而且高Ca2+水平有利于Cd2+被菌丝吸收.     

Cd、Ni单一及复合污染对土壤酶活性的影响

采用外源添加重金属和露天盆栽实验研究了Cd、Ni对含羞草、三叶草根际土壤脲酶、过氧化氢酶和蔗糖酶活性的影响。结果表明,Cd、Ni单一污染条件下,低浓度的Cd、Ni对含羞草组、三叶草组的脲酶、过氧化氢酶有激活作用,高浓度的Cd、Ni对土壤脲酶、过氧化氢酶有一定的抑制作用;对蔗糖酶有较强的抑制作用。在Cd、Ni复合污染条件下,对含羞草组、三叶草组的脲酶、过氧化氢酶和蔗糖酶产生抑制作用;Cd、Ni单一及复合污染对土壤酶活性的抑制大小顺序为:脲酶>蔗糖酶>过氧化氢酶,其中土壤脲酶可以作为Cd、Ni污染的预警指标。含羞草能显著提高土壤脲酶、过氧化氢酶和蔗糖酶的活性,修复能力大于三叶草,在Cd、Ni污染修复方面有很好的应用前景。     

Analyzing maps of dispersal around a single focus

The spatial pattern of organisms may be used to characterize their dispersal, quantify spread or estimate the point of introduction of an alien species. Their distribution may be represented by maps of individuals, or by counts or by presence/absence at known positions within a sampled area. The problems and relative merits of these different forms of data for spatial inference are discussed. Three datasets concerning dispersal from a single focus are analyzed: counts of aphids, Rhopalosiphum padi and Sitobion avenae, on barley plants, Hordeum vulgare, grown in experi- mental trays; mapped locations of couch grass, Elymus repens, tillers within plots of a field experiment; locations of sightings of the lupin aphid, Macrosiphum albifrons, as it invaded Great Britain between 1981 and 1984. A method for generating maps from counts is proposed to overcome problems caused by recording imprecision. Several statistics are used to quantify dispersal and spatial pattern in the experimental data and together provide a clear picture of the spatial pattern observed; they enabled several effects of the experimental treatments to be identified. The value of the statistics are compared. Estimates of the source of the lupin aphid invasion are obtained using the backtracking methods of Perry (1995b) and do not contradict previous suggestions.     

气候因子对混播草地不同种群生长及其个体消长的影响

采用数理统计方法 ,研究了混播草地中黑麦草 (Lolium perenne)、白三叶 (Trifoliumrepens)和白苞蒿(Artemisialactiflora)的生长特征及其个体消长特点 ,分析了主要气候因子 (温度、降水和日照 )对其构件生长的影响 .温度对黑麦草分蘖的负效应显著 (P〈0 .0 1) ;温度和降水与黑麦草叶片、白三叶匍匐茎和白苞蒿侧枝生长存在显著 (P〈0 .0 1)或弱显著 (P〈0 .1)正相关 ;日照对 3种植物的生长有不同程度抑制作用 .温度和日照对植物生长的互作效应大于温度和降水的互作效应 .黑麦草分蘖数与白三叶分枝数相互消长 ,而黑麦草叶片与白三叶匍匐茎生长具相互促进作用 ;白苞蒿侧枝和白三叶匍匐茎生长相互促进 ,其生长点数则由相互促进向相互抑制转化 ;黑麦草与白苞蒿种群生长具正效应作用 .黑麦草叶片、白三叶匍匐茎和白苞蒿侧枝生长具明显季节动态性 ,而黑麦草分蘖、白三叶分枝和白苞蒿侧芽数季节性变化不明显 .黑麦草分蘖和白苞蒿侧芽具夏秋发生优势 ,而黑麦草叶片生长具春末潜势 ,白苞蒿侧枝具旺盛期 (6～ 9月 )生长优势 .图 1表 3参 2 7     

喀斯特地区红三叶混播草地群落对长期适度放牧的响应

群落稳定性的生态学研究一直缺乏动物利用条件下的长时间梯度田间试验,而混播草地的放牧利用年限是生态脆弱的南方喀斯特山区生态环境建设和资源可持续利用的关键问题之一。用考力代绵羊轮牧,在牧前和牧后草地现存量(干物质,DM,drymatter)分别为1800~2500(草层高15~18cm)和900~1200kg·hm-2(草层高3~5cm)的适度放牧利用条件下,对亚热带最常见的豆科牧草红三叶(Trifolium pratense)与禾本科牧草的两两混播草地的群落生产力和持久性开展长期研究。20年的结果表明:适度放牧利用下,群落地上总生物量长期稳定,各组合间差异不显著,总盖度20a后仍高达97%以上;适度放牧有利于牧草的生产力持久性,红三叶、鸭茅(Dactylisglomerata)、多年生黑麦草(Loliumperenne)和黑穗画眉草(Eragrostisnigra)都在群落中长期存在;群落净产量和持久性是尺度依赖的,群落长期净生产力以红三叶 鸭茅的最高(DM产量353.3g·m-2·a-1)(P<0.05),对杂草侵入的抵抗力最强,而前10a红三叶 多年生黑麦草有很高的净生产力(DM产量449.8g·m-2·a-1);物种的生产力受伴生种的影响,前10a红三叶在与无芒雀麦(Bromus inermis leyss)和黑穗画眉草组合中的产量高于其它组合(P<0.05);不同的物种侵占力不同,栽培种侵占力最强的是黑穗画眉和鸭茅,非栽培种侵占力最强的是白三叶。