Effects of six grassland plant species on soil nematodes: A glasshouse experiment

The effects of six individual plant species on the abundance and composition of nematode communities were studied in a glasshouse experiment during 16 weeks. The effect of the presence of plants, the correlation between nematode abundance and plant biomass, the response of plant-feeding nematodes and other nematode groups to different plant species was examined and also whether the effect differed between plant species within a plant functional group. The total number of nematodes increased during the study period in all treatments, although in some treatments, the increase levelled off after 8 or 12 weeks. The identity of the plant species affected both the total abundance of nematodes and the nematode community composition. The number of bacterial-feeding nematodes was greatest under grasses and legumes and was positively correlated with shoot biomass and negatively with root biomass. The response of the plant-feeding nematodes, which differed in abundance under both the investigated legume and the forb species, suggests that the identity of the plant species is more important than the plant functional group. A possible explanation could be related to differences in plant secondary metabolites. Despite some differences in the nematode species pool, the effects of plant species appear quite consistent between the present glasshouse study and previous field experiments.     

极低频脉冲电场与高压静电场对作物种子萌发影响的差异

为了明确基于极低频脉冲电场(pulsed electric field,PEF)的种子处理技术与基于高压静电场(highvoltage electrostatic field,HVEF)的种子处理技术的有效性及其差异,研究了极低频PEF和HVEF对绿豆生长的影响。结果表明,极低频PEF处理对绿豆幼苗的质量、芽长和根长都有明显的促进作用,相同强度的HVEF处理对绿豆幼苗的根长生长有一定促进作用,对芽长的影响不显著。机理研究显示,极低频PEF和HVEF处理均对萌发绿豆的氧化代谢和蛋白质代谢有一定影响,在种子萌发初期,极低频PEF处理促进了种子储藏蛋白的分解,在后期促进了新蛋白的合成,HVEF处理则对萌发后期的蛋白合成有一定促进作用。研究还发现,极低频PEF和HVEF均可通过诱发超氧阴离子自由基激活种子超氧化物歧化酶(SOD)活性,促进过氧化物酶(POD)的合成,但是,极低频PEF对SOD和POD的影响大于HVEF。讨论了极低频PEF和HVEF对绿豆萌发影响差异的原因。     

聚丙烯酰胺对几种植物种子萌发及生长的影响

用不同浓度聚丙烯酰胺溶液处理苜蓿、狗尾草、沙棘等8种草本、灌木植物发芽试验结果表明,聚丙烯酰胺溶液浓度为0.1-1.0g/kg时,对鸡眼草、沙棘、苜蓿、草木樨种子萌发有促进作用,对其幼苗苗高、根长的影响除个别有较小抑制作用外,均表现促进作用。当溶液浓度为0.5g/kg时,对兴安胡枝子种子幼苗的根系生长则表现出显著抑制作用,而对荆条种子萌发表现出极显著抑制作用。聚丙烯酰胺各处理浓度均对黄白草、狗尾草萌发表现出极显著或显著抑制作用,而对其幼苗苗高、根长表现出显著促进或较小的抑制作用。     

Effects of soil properties and trace metals on urease activities of calcareous soils

A study was conducted to investigate the relationship between urease activity and some physical, chemical, and microbiological properties of soils from central Iran. Inhibitory effects of Cr, Cd, and Pb on urease activity were also studied. Results indicated that no significant difference was observed between urease activity of field-moist and air-dried soils. Soil organic C and total N correlated highly significantly with urease activity, with r values of 0.899*** and 0.797***, respectively. There was also a significant correlation between urease activity and the number of bacteria grown on urea-agar media, with r value of 0.470*. A significant negative correlation (r =–0.492*) was observed between urease activity and electrical conductivity of saturation paste extracts. There were no significant correlations between urease activity and soil textural properties, pH, calcium carbonate equivalent, cation exchange capacity, and populations of soil bacteria on nutrient agar and population of soil fungi on potato dextrose agar. Both Cd and Pb inhibited urease activity to a similar extent and to a greater extent than did Cr.     

Physiological and biochemical metabolism of germinating broccoli seeds and sprouts

Changes in physiological and biochemical metabolism as well as glucoraphanin and sulforaphane contents of germinating broccoli seeds and sprouts were investigated in this study. Sprout length, root length, and fresh weight increased with germination time. Dry weight varied from 2.5 to 3.0 mg per sprout. A rapid increase in respiratory rate of sprouts occurred between 24 and 36 h of germination and then stayed at a high level. HPLC analysis found that glucoraphanin content increased at the early stage (0-12 h) of germination, decreased to a low value of 3.02 mg/g at 48 h, and then reached the highest value of 6.30 mg/g at 72 h of germination. Sulforaphane content decreased dramatically during the first day of germination, then increased slowly, and reached a high value of 3.38 mg/g at 48 h before declining again.     

Activated carbon addition affects substrate pH and germination of six plant species

Activated carbon (AC) is widely used in ecological studies for neutralizing allelopathic compounds. However, it has been suggested that AC has direct effects on plants because it alters substrate parameters such as nutrient availability and pH. These side-effects of AC addition may interfere with allelopathic effects. In this study we analyzed three widely used commercial AC brands and analyzed their effect on pH, their ability to retain glucosinolates, and their effect on the germination of six plant species. AC brands differed significantly in their effect on pH values when added to different substrates. Glucosinolates were completely adsorbed by all brands, indicating that AC is suitable as adsorbent for this compound class. Finally, AC addition to substrates had differential effects on seed germination of Arabidopsis thaliana, Plantago lanceolata, Solidago canadensis, and Lotus corniculatus, whereas no effect was found on the germination of Lactuca sativa and Brassica oleracea. We suggest that scientists using AC should always include an experimental control to test for direct effects of AC addition on both substrate parameters and plant performance.     

Phosphorus and liming effects on early growth of selected plant species grown on an ultisol

Abstract

A series of pot experiments were conducted to test the effect of phosphorus (P) application and liming on early growth performance of Zea mays, Mucuna pruriens and nine woody species (Albizia ferruginea, Cajanus cajan, Dactyladenia barteri, Dalbergia sissoo, Enterolobium cyclocarpum, Flemingia macrophylla, Gliricidia sepium, Leucaena leucocephala, and Pentacletra macrophylla) on an Ultisol. Low reponse to liming and high response to P application were observed in this trial. Early top growth of the eleven species was correlated to seed size and seed nitrogen (N), P, and calcium (Ca) contents. Highest correlation was observed with seed P content (r = 0.896^**). Large seeded size species (D. barteri, E. cyclocarpum, M. pruriens, and P. macrophylla) showed the least reponse to P application, while the remaining small seeded size species showed significant responses to P application. The large seeded species also showed relatively less increases in N, P and Ca uptakes with P application and liming. The pot test can be used in prescreening of woody species for use on low P and acid soils. The results also emphasize the need for seed size consideration in multipurpose trees and shrubs selection for establishment in low P and on degraded soils     

Comparison of digestion methods for determination of trace and minor metals in plant samples

In this paper, three dissolution methods using pressure digestion vessels (low-, medium-, and high-pressure vessels) for the determination of metals in plant samples are described. The Plackett-Burman saturated factorial design was used to identify the significant factors influencing wet ashing and to select optimized dissolution conditions. The three methods were statistically compared (on-way ANOVA) on the same sample; no significant differences were obtained. In all cases the relative standard deviation values were <3%. The digestion method based on the use of low-pressure vessels and a microwave oven was validated against CRM GBW07605 tea leaves. This method was applied to the determination of Cu, Zn, Mn, Fe, Mg, and Ca in 22 different medicinal, aromatic, and seasoning plants by flame-atomic absorption spectrometry. The concentration intervals of metal in the plants analyzed were the following: Cu, 4 (Allium sativum)-35 (Thea sinensis) microg g(-1); Zn, 7 (Piper nigrum)-90 (Betula alba) microg g(-1); Mn, 9 (Allium sativum)-939 (Caryophylus aromaticus) microg g(-1); Fe, 33 (Allium sativum)-2486 (Anethum graveolens) microg g(-1); Mg, 495 (Allium sativum)-7458 (Ocimum basilicum) microg g(-1); Ca, 386 (Allium sativum)-21500 (Ocimum basilicum) microg g(-1).     

典型潮土剖面主要性质和微量金属垂直分布特征

对不同利用方式下石灰性潮土剖面主要性质和微量金属元素含量垂直分异规律进行了初步研究。结果表明,长期耕种的菜地和旱地0～15cm表层土壤有机碳含量高于其他土层,pH和CaCO3含量低于下层土壤;表层土壤Cd已明显积累;但Cd、Pb、Cu、Zn含量均未超过国家土壤环境质量二级标准。几种微量金属全量在菜地和旱地表层土壤之间没有显著差异,但菜地表层土壤DTPA可提取态Cd含量显著高于旱地。从微量金属的剖面分布看,石灰性潮土全量Cd和DTPA可提取态Cd、Pb、Cu、Zn均有明显的表聚现象,这种分布与土壤有机碳含量、pH和CaCO3含量显著相关。聚类分析表明,该区域耕作土壤环境分析样品的采集以表层土壤0～15cm多点混合样品为宜。     

Effect of processing conditions on trace elements in fish roe from six commercial new zealand fish species

The concentrations of trace elements in fish roes and the effect of processing conditions (karasumi-like or karashi mentaiko) were investigated in six commercial fish species from New Zealand. The studied elements were As, Cd, Cr, Cu, Hg, Pb, and Zn, and the roes were from the following species: chinook salmon ( Oncorhynchus tshawytscha), hoki ( Macruronus novaezelandiae), southern blue whiting ( Micromesistius australis), hake ( Merluccius australis), blue warehou ( Seriolella brama), and barracouta ( Thyrsites atun). The concentrations of As, Cd, Cr, Hg, and Pb in the roes were lower than literature values for fish muscles. Only Zn in barracouta roe and Cu in salmon roe and their products were relatively higher than the generally accepted levels in fish muscles and could be of safety concern. Hence, the consumption of barracouta and salmon roes among certain parts of the population needs to be monitored and assessed. Dry salting (karasumi-like) processing increased ( P < 0.001) the concentrations of the studied trace elements while salting fermentation (karashi mentaiko) processing tended to decrease the levels of trace elements. Fermentation may be a useful process to decrease the level of toxic trace elements.     

Effects of liming and selected heavy metals on ammonium release in waterlogged agricultural soils

Many farmlands are periodically flooded or ponded by excessive precipitation resulting in changes to soil chemical and biochemical properties. In this study, one set (eight treatments with four replications) of field-moist surface soils (0–15 cm) and their air-dried counterparts obtained from a long-term liming experiment were incubated at 30 °C under waterlogged conditions for 10 days, and the amounts of net NH₄ ⁺-N released (soluble and exchangeable) were determined after extraction with 4 M KCl. Another set of three surface soils were used to evaluate the effect of six heavy metals on the NH₄ ⁺-N release under waterlogged conditions. Results showed that increasing the liming rate from 0 to 17,930 kg ha^?1 effective calcium carbonate equivalent increased the average soil pH from 4.98 to 7.06, averages of the amounts of NH₄ ⁺-N released ranged from 1.6 to 5.2 mg N kg^?1 field-moist soil, and the corresponding amounts released in air-dried soils ranged from 18.9 to 32.9 mg N kg^?1 soil. This increase of the amount NH₄ ⁺-N released in air-dried soil samples is presumably due to a slaking effect. At 5 mmol kg^?1 soil, all six heavy metals inhibited the NH₄ ⁺-N released. The relative effectiveness of the heavy metals in inhibition of the NH₄ ⁺-N released varied among the three soils. Lead(II) was the most effective inhibitor of NH ₄ ⁺-N release in Clarion and Harps soils and Cd(II) in Harps soil. Cobalt(II), Cu(II), and Cd(II) were the least effective inhibitors of NH₄ ⁺-N release in Clarion, Harps, and Okoboji soils, respectively.     

Chemical composition of selected edible nut seeds

Commercially important edible nut seeds were analyzed for chemical composition and moisture sorption. Moisture (1.47-9.51%), protein (7.50-21.56%), lipid (42.88-66.71%), ash (1.16-3.28%), total soluble sugars (0.55-3.96%), tannins (0.01-0.88%), and phytate (0.15-0.35%) contents varied considerably. Regardless of the seed type, lipids were mainly composed of mono- and polyunsaturated fatty acids (>75% of the total lipids). Fatty acid composition analysis indicated that oleic acid (C18:1) was the main constituent of monounsaturated lipids in all seed samples. With the exception of macadamia, linoleic acid (C18:2) was the major polyunsaturated fatty acid. In the case of walnuts, in addition to linoleic acid (59.79%) linolenic acid (C18:3) also significantly contributed toward the total polyunsaturated lipids. Amino acid composition analyses indicated lysine (Brazil nut, cashew nut, hazelnut, pine nut, and walnut), sulfur amino acids methionine and cysteine (almond), tryptophan (macadamia, pecan), and threonine (peanut) to be the first limiting amino acid as compared to human (2-5 year old) amino acid requirements. The amino acid composition of the seeds was characterized by the dominance of hydrophobic (range = 37.16-44.54%) and acidic (27.95-33.17%) amino acids followed by basic (16.16-21.17%) and hydrophilic (8.48-11.74%) amino acids. Trypsin inhibitory activity, hemagglutinating activity, and proteolytic activity were not detected in the nut seed samples analyzed. Sorption isotherms (Aw range = 0.08-0.97) indicated a narrow range for monolayer water content (11-29 mg/g of dry matter). No visible mold growth was evident on any of the samples stored at Aw < 0.53 and 25 degrees C for 6 months.     

Aquatic humic substances inhibit clastogenic events in germinating seeds of herbaceous plants

One humic acid (HA) and two fulvic acids (FAs) of aquatic origin have been tested for their capacity to inhibit clastogenic events caused by maleic hydrazide (MH) in germinating seeds of the herbaceous plant species Allium cepa and Vicia faba. Either HA or FA at concentrations of 50 and 500 mg L(-)(1) was interacted with 10 mg L(-)(1) MH for 24 h before addition to the seeds. The evaluation of genotoxic activity was made by counting micronuclei (MN) and aberrant anatelophases (AT) in root tip cells after treatment with HA or FA alone, MH alone, and interacted HA + MH and FA + MH. Regular AT were also counted as an index of mitotic activity. In all cases HA and FA interacted with MH showed an evident anticlastogenic action indicated by the marked reduction of genetic anomalies. In A. cepa, the anticlastogenic effect of HA and FA was more significant for aberrant AT than for MN, whereas the opposite was true in the case of V. faba. The protective effect exhibited for both anomalies by HA was slightly higher than that of the corresponding FA in A. cepa, whereas no significant differences between these HA and FA treatments were observed in the case of V. faba. The two FAs generally showed similar anticlastogenic behaviors with slight quantitative differences observed as a function of the type of anomaly and the plant species. The effects of HA and FA concentration differed depending on the type of anomaly observed, the plant species, and FA origin. In V. faba, cell division, that is, the number of regular AT, was generally depressed by HA and FA at either concentration with respect to the control. In A. cepa, HA and FA produced either stimulating or inhibiting effects on regular AT depending on their nature, origin, and concentration.     

Food grade fungal stress on germinating peanut seeds induced phytoalexins and enhanced polyphenolic antioxidants

The effects of food grade fungus Rhizopus oligosporus stress on phytochemicals and phytoalexins of germinating peanut seeds were investigated by comparing the metabolic profiles of ungerminated (UG), germinated (G), and germinated seeds under fungal stress (GS). Three types of peanut seeds with different skin color (red, reddish brown, and black) were compared in the process. The polyphenolic contents were analyzed and correlated with antioxidant capacity for specific free radicals including peroxyl radical ROO(?) (ORAC), hydroxyl radical HO(?) (HORAC), superoxide radical O(2)(?-) (SORAC), and DPPH radical. The polyphenolic fingerprints analyzed by HPLC and LC-MS(n) showed that phenolic acids (coumaric, sinapinic, and ferulic acids derivatives) were the major group of phenolic compounds in ungerminated seeds. G or GS increased the level of phenolic acids, phytoalexins, and antioxidant capacity values in reddish and red peanuts but not in black peanuts. From the LC-MS(n) spectral data, 45 compounds were identified tentatively in the germinated peanuts, including 14 coumaric acids, 3 ferulic acids, 4 sinapinic acids, 2 hydroxybenzoic acids, 1 caffeic acid, 2 flavonoids, and 19 stilbenoids derivatives. Reddish brown germinated peanuts produced the highest amount of phytoalexins after GS with 55 compounds detected. Forty-five of these compounds were suggested as stilbenoid phytoalexins derivatives. The high content of phytoalexins may enhance the bioactivity of peanut seeds as functional food ingredients.     

Cyanide effects on transport of trace metals in plants

Abstract

Cyanide at levels of 50 to 100 μg NaCN/g soil was not only toxic to bush bean plants, but also resulted in increased uptake of Cu, Co, Ni, Al, Ti, and, to a slight extent, of Fe. Either the phytotoxicity from the cyanide or the metals resulted in increased transport of Na to leaves from roots. In studies with ¹⁴C‐cyanide the transport of some cyanide into plants and to leaves simultaneously with the metals was demonstrated. There was a root, stem, leaf gradient for ¹⁴C. From solutions, cyanide resulted in increased plant uptake somewhat of Cu, Zn, and Fe. The results have bearing on the use of cyanide as a metabolic inhibitor as well as on phytotoxicities of metals.     

Effects of insularisation on plant species richness in the prairie-forest ecotone

Data on plants from five groups of remnant prairies and forests in the prairie-forest ecotone of the midwestern United States show that: (1) Archipelagos of small sites tend to contain more species than do single large ones of equal total area. (2) No species are excluded from small sites. (3) Small sites tend to have surprisingly many species, and large sites surprisingly few, relative to a random colonisation model. (4) ‘Rare’ species (those that occur in only one site) are found more often in small sites than a random colonisation model would predict. (5) There is no evidence for any of these sites that species number is ‘relaxing’, but all these sites have been remnants for only a short time. Result (1) is consistent with results from similar studies on other taxa and suggests that there is no automatic reason to believe that species richness is maximised by single large refuges.     

Antagonistic effect of gibberellic acid and boron on protein and carbohydrate metabolism of soybean germinating seeds

Lots of soybean seeds (Glycine max L. Merr. cv MG 13 G2) were pretreated with solutions of boron (1 or 2 μg/ml) or/and gibberellic acid (GA₃) (0.1 μg/ml) during three hours, and germinated in a culture chamber at 24°±1°C. Germination and seedling growth were inhibited by boron. GA₃ activated both processes and partially reversed the inhibitory effect of the microelement. This protective effect of GA₃ against the negative action of boron is particularly due to the antagonism GA₃ /boron on protein and carbohydrate metabolism during the seed germination process.     

Effects of Collembola on root properties of two competing ruderal plant species

Plant roots compete for nutrients mineralised by the decomposer community in soil. By affecting microbial biomass and activity Collembola influence the nutrient availability to plants. We investigated the effect of Collembola (Protaphorura fimata Gisin) on growth and competition between of two plant species, Cirsium arvense L (creeping thistle) and Epilobium adnatum Griseb. (square-stemmed willow herb), in a laboratory experiment. Two seedlings of each plant species were planted in rhizotrons either in combination or in monoculture (intra- and interspecific competition). Interspecific competition strongly reduced total biomass of C. arvense whereas E. adnatum suffered most from intraspecific competition. Collembola neither affected the competitive relationship of the two plant species nor shoot and root biomass. Although Collembola did not affect total root biomass they influenced root morphology of both plant species. Roots grew longer and thinner and had more root tips in presence of Collembola. Root elongation is generally ascribed to the exploitation of nutrient rich patches in soil. We hypothesise that changes in root morphology in presence of Collembola are due to Collembola-mediated changes in nutrient availability and distribution.     

Mapping of trace metals in urban soils

Spatial distribution maps depicting the concentrations of antimony, lead, tin, copper and zinc, and the presence of land-use units were generated for Mühlburg, a district of the City of Karlsruhe, Germany. The influence of the spatial land-use structure on the distributions of the element concentrations is statistically evaluated and discussed. The variography for Mühlburg shows an average range of 200-400 m for the spatial correlations of Sb, Pb, Sn and Zn. The variograms of Pb and Zn are characterised by hole effects at 300 m distances, i.e. the result of repeated stronger spatial correlations for certain distances between the sample sites. Most probably, this is an effect of the typical urban structure of streets, buildings, green spaces, and industry. Kriging method was used for the interpolation of Sb, Pb, Sn and Zn concentrations. Only Cu does not show a spatial correlation. In this case, the interpolation was carried out with a smoothed triangulation routine. Pollution plumes of point sources such as lead works, a bell foundry and a coal-fired thermal power station superimpose the more diffuse pollution from traffic, household heating processes, waste material disposal, etc. The trace element concentrations in soils of housing areas increase with the age of the developed area. Industrial areas show the highest level of pollution, followed by housing areas developed before 1920, traffic areas, allotments, housing areas developed between 1920 and 1980, parks and sports areas, cemetery and housing areas developed after 1980. It is demonstrated that spatial distribution maps of element concentrations indicate potential emission sources of harmful substances, even if the emission itself or the direct surrounding soil have not been analysed. The analytical tools presented enable town planners to discern areas of higher soil pollution. Detailed investigations can be focussed on these areas to evaluate the possibilities of soil usage and transfer. These methods enable one to manage urban soil in an adequate manner. For these reasons, the methods demonstrated support an urban environmental impact assessment and are a part of a sustainable urban soil management.