Phytoremediation of Oil-Sludge–Contaminated Soil

The aim of this research was to select plant species that could be effective in the phytoremediation of a former oil-sludge pit. Seven crop plants (Triticum aestivum L., Secale cereale L., Avena sativa L., Hordeum vulgare, Sorghum bicolor L. Moench, Panicum miliaceum L., and Zea mays L.), five wild grasses (Lolium perenne L., Bromopsis inermis, Agropyron cristatum L., Agropyrum tenerum L., and Festuca pratensis Huds.), and three legumes (Medicago sativa L., Trifolium pratense L., and Onobrychis antasiatica Khin.) were screened for phytotoxicity, including the assessment of germination, shoot biomass, and root biomass, in a pot experiment. The estimation of oil-sludge degradation in the root zone of the tested plants showed that rye accelerated cleanup most effectively, degrading all of the main contaminant fractions in the oil sludge by a total of 52%. Although alfalfa had a lower phytoremediation potential than did rye, it maintained large numbers of soil microorganisms, including polycyclic aromatic hydrocarbon degraders, in its rhizosphere. Rye and alfalfa were chosen for a large-scale study to remediate an oil-sludge pit on the grounds of a petroleum refinery. Remediation monitoring confirmed the effectiveness of rye: the oil-sludge content decreased consistently for 3 years and remained low in comparison with the results from other plant species.     

Aluminium speciation in the presence of wheat root cell walls: a wet chemical study

Hydrolysis of Al³⁺ was performed in the presence of isolated root cell walls from a series of wheat cultivars (Triticum aestivum L.) known to have differential tolerance to Al contamination. Aluminium speciation was dependent on the cell wall concentration. At low cell wall concentrations, significant amounts of the very toxic Al₁₃ species were formed. At higher cell wall concentrations, formation of the tridecamer was hindered or completely inhibited. The sensitive wheat cultivars displayed a higher affinity for aluminium than the tolerant cultivars. A possible Al tolerance mechanism based on cell wall permeability is discussed.     

Non-phytotoxicity of the aluminum sulfate ion, AlSO+4

Aluminum is a phytotoxic element in many soils and occurs in a variety of chemical species. In order to determine whether AlSO⁺₄ is toxic, seedlings of wheat (Triticum aestivum L. cv. Tyler) and red clover (Trifolium pratense L. cv. Kenland) were transferred to solutions containing controlled activities of Al³⁺, AlSO⁺₄, Na⁺ and Ca²⁺. Root elongation was inhibited by Al³⁺ (or mononuclear hydroxy-Al species that are in equilibrium with Al³⁺), but not by AlSO⁺₄. We assumed a formation constant (K_AlSO⁺₄= {AlSO⁺₄}/[{Al³⁺} {SO^2-₄}]; braces indicate activities} of 10^3.2 for AlSO⁺₄ in the computation of ionic activities, but use of K_AlSO⁺₄ values ranging from 10^2.8 to 10^3.6 had very little effect on the computed toxicities of Al³⁺ and AlSO⁺₄. Sulfate did not promote the formation of polynuclear Al complexes in our experiments. A practice in studies of Al phytotoxicity has been to attribute toxicity to mononuclear Al, but now it would seem advisable to exclude AlSO⁺₄. That AlSO⁺₄ is non-toxic, or is at least 10-fold less toxic than Al³⁺, has implications for the physiology of Al toxicity and for the use of sulfate salts in experimental work and in agriculture.     

Electron-probe Microanalysis Studies of Silicon in the Elongating Basal Internodes of Avena sativa (L.), Hordeum sativum (Jess.) and Triticum aestivum (L.)

Silicon deposits in the elongating basal internodes of almostmature, field grown specimens of Avena sativa, Hordeum sativumand Triticum aestivum were investigated using electron-probemicroanalysis. In A. sativa and H. sativum silicon was foundto be confined to the cells in the endodermal layer, being presentwithin the inner tangential and radial walls, and occasionallyin the outer tangential wall. In T. aestivum some silicon wasalso located in walls of cells surrounding the vascular bundles. The anatomy of the internodal tissues is discussed for the threespecies from light micrographs. The endodermal layer is discontinuousin A. sativa and H. sativum, in the former species it partlyextends around individual vascular bundles. In T. aestivum itforms a complete cylinder around the stelar region and alsoshows considerably more thickening of the inner tangential wallthan in the other species. The results are discussed in relation to the anatomy of theinternodal tissues and the possible function of silicon in theendodermis. Avena sativa L., Hordeum sativum Jess, Triticum aestivum L., oat, barley, wheat, silicon deposition, electron-probe microanalysis     

Effect of aluminium on yield and plant chemical concentrations of some temperate legumes

The aluminium (Al) tolerance of 34 temperate legume species (143 genotypes, including 57 from Trifolium repens) was determined in 60 experiments over a 3 year period in a low ionic strength (2.7 × 10^-3 M) solution culture. For each genotype, the relationship between solution Al³⁺ activity (M) and relative yield was determined and the Al³⁺ activity associated with a 50% reduction in yield (Al_RY50) calculated. In addition, plant chemical concentrations were determined in at least one genotype from most species. For white clover, Al_RY50 over all genotypes had an approximately normal distribution with mean of 1.31 M for the tops and 1.51 M for the roots, and a standard deviation of about 0.4. This suggested that Al tolerance had a polygenic inheritance. For the other species tested, Al_RY50 ranged from 0.15 to 4.53 M in the tops and from 0.21 to 4.89 M in the roots. In the tops and roots, 37% and 26% respectively of the genotypes had an Al_RY50 less than 1 M, including all species tested in the genera Melilotus and Medicago. Only 8% or 23% of the genotypes, based on the tops and roots respectively, had an Al_RY50 greater than 2, including all genotypes in the species Lotus pedunculatus. Except for Lotus, there were no consistent differences between genera in plant chemical concentrations. In Lotus, concentrations of Ca, Zn, Mn and Cu in the tops and of all elements except B in the roots were lower than that of the other species. The Al_RY50 of the species was not related to plant chemical concentrations in the absence of Al. Depending on the plant element, increasing solution Al concentrations had no significant effect on plant chemical concentrations for 56–94% of the species. When a significant effect did occur, increasing Al in solution generally decreased S and K concentrations and increased Mn, Zn, Cu Fe, B and Al concentrations in the tops and roots and decreased Ca concentrations in the tops. Plant P concentrations decreased in the tops but increased in the roots. Increasing Al in solution increase plant Al at the average rate of 44 g g^-1 M ^-1 (range 20–87) in the tops and 333 g M ^-1 (range 162–616) in the roots.     

Natural occurrence of entomophthoroid fungi (Entomophthoromycota) of aphids (Hemiptera: Aphididae) on cereal crops in Argentina

The spectrum of entomophthoroid fungal species parasitising aphids on cereal crops and a study of the phenology and prevalence of these pathogens were investigated in Argentina. The studies were conducted at six different sites cultivated with crops of Triticum aestivum (wheat), Avena sativa (oats) and Sorghum bicolor (sorghum) during two consecutive years. Entomopathogenic fungi from the new phylum Entomophthoromycota were recorded from six aphid species on cereals in Argentina: Rhopalosiphum maidis, Rhopalosiphum padi, Rhopalosiphum rufiabdominalis, Schizaphis graminum, Sitobion avenae and Sipha maydis. Three species of entomophthoroid fungi were found infecting these aphid species: Pandora neoaphidis, Zoophthora radicans (Entomophthorales: Entomophthoraceae) and Neozygites fresenii (Neozygitales: Neozygitaceae). Entomophthoroid fungal infections occurred mostly in autumn–winter seasons (March–August), and coincided with periods of high relative humidity and comparatively low temperatures. This study represents the first base‐line characterisation of entomophthoroid fungi infecting aphids on cereal crops in Argentina.     

Assessing the phytotoxicity of mononuclear hydroxy-aluminum

Abstract Al³⁺ is an important rhizotoxic ion in acid soils around the world. Al³⁺ is in equilibrium with mononuclear hydroxy-Al species, such as AlOH²⁺ and AL(OH)₂⁺, but the toxicity of these species has not been determined. Polynuclear Al may also coexist with Al³⁺, and one of these species, AlO₄Al₁₂(OH)₂₄(H₂O)₁₂⁷⁴, is very toxic. In order to determine the toxicity of mononuclear hydroxy-Al we have reanalysed the results of previously published, solution-culture experiments and have performed new experiments. Several problems are inherent in these studies. At pH values less than 5.0, the activities of the mononuclear hydroxy-Al species are low relative to Al³⁺, but attempts to change the ratio by raising the pH generally initiate the formation of polynuclear Al. (We discovered that mononuclear solutions are stable for many days when {Al³⁺}/{H⁺}³≤ 10^8.8, where braces denote activities.) We avoided, or accounted for, polynuclear Al in our studies. In addition, we used up-to-date equilibrium constants to compute Al species, very simple culture media (generally containing CaCl₂, AlCl₃ and HCl as the only inputs), short-term (2d) growth, and an Al-sensitive wheat variety (Triticum aestivum L. cv. Tyler) that permitted low Al levels and, consequently, higher pH values without Al polymerization. Experiments were designed in which the solutions were constant in {Al³⁺} and variable in mononuclear hydroxy-Al or were orthonal (factorial) in {Al³⁺} and {AlOH²⁺}. Linear and nonlinear, simple and multiple, regression analyses of these and previous experiments failed to reveal any toxicity for mononuclear hydroxy-Al to Tyler wheat.     

Interplanting Annual Ryegrass,Wheat, Oat,and Corn to Mitigate Iron Deficiency in Dry Beans

This study evaluated whether grass intercropping can be used to alleviate Fe deficiency chlorosis in dry beans (Phaseolus vulgaris L.) grown in high pH, calcareous soils with low organic matter. Field studies were conducted at the University of Wyoming Sustainable Agriculture Research and Extension Center in 2009 and 2010. Black- and navy beans were grown alone or intercropped with annual ryegrass (Lolium multiflorum Lam.), oat (Avena sativa L.), corn (Zea mays L.), or spring wheat (Triticum aestivum L.) in a two-factor factorial strip-plot randomized complete block design. All four grass species increased chlorophyll intensity in dry beans. However, grass species did not increase iron (Fe) concentration in dry bean tissues suggesting inefficient utilization of Fe present in the dry bean tissues. In 2009, nitrate-nitrogen (NO₃-N) and manganese (Mn) concentration in bean tissue were greater in bean monoculture than in grass intercropped beans. Bean monoculture also had greater soil NO₃-N concentrations than grass intercropped treatments. In 2009, grass intercrops reduced dry bean yield >25% compared to bean monoculture. Annual ryegrass was the least competitive of the four annual grass species. This suggests that competition from grasses for nutrients, water, or light may have outweighed benefits accruing from grass intercropping. Additional studies are required to determine the appropriate grass and dry bean densities, as well as the optimum time of grass removal.     

THE PRESENCE OF PROTEASE-DIGESTIBLE MATERIAL IN GOLGI VESICLES DURING ENDOSPERM DEVELOPMENT OF SELECTED CEREALS

The presence of dictyosomes secreting densely stained vesicles throughout endosperm protein body formation was confirmed for four cereals (rice, Oryza sativa L.; hard red winter wheat, Triticum aestivum L.; winter feed barley and spring malting barley, Hordeum vulgare L.; oats, Avena sativa L.). The contents of the Golgi vesicles and protein bodies were digested with proteases for all cereals except rice. It was found in the case of rice that OsO₄ altered the proteins in the Golgi apparatus and protein bodies making them resistant to protease digestion. These results imply that the Golgi apparatus plays an important role in the concentration and transport of storage proteins into vacuoles.     

N2 fixation, N transfer, and yield in grassland communities including a deep-rooted legume or non-legume species

Background and aims

Legumes are important components of grassland mixtures due to their ability to sustain high yields with moderate nitrogen inputs. This study investigates nitrogen relationships in mixtures of Trifolium pratense and grasses into which a deep-rooted forb was included, and particularly whether these realtionships differ when the forb is a legume or a non-legume species.

Methods

A field experiment in which mixtures of T. pratense, Phleum pratense, Lolium perenne, and Medicago sativa or Cichorium intybus, and monocropped stands of all species was established in 2007 and harvested in 2008 and 2009. The experiment received a total input of 100 kg?ha^?1?N yearly. Yield and botanical composition were determined in seven harvests. Species were analysed for ¹⁵N abundance, and N₂ fixation and N transfer were calculated. Soil samples were analysed twice for inorganic N.

Results

Non-legumes benefitted from the presence of legumes in terms of N concentration, and the yield of mixtures exceeded that of monocropped non-legumes but not monocropped legumes. The mixture containing M. sativa did not yield more DM or N than did the mixture containing C. intybus. A total of 17.08 kg?N ha^?1 was transferred from T. pratense to the non-legumes in the mixture in which it was the sole legume species.

Conclusions

It is concluded that there was a synergy effect in species mixtures, but the effect did not differ between the two deep-rooted species.     

The content of N-acylphosphatidylethanolamines in the seeds of cultivated plants and grain products

The content of the minor class of phospholipids, N-acylphosphatidylethanolamines (NAPEs) in mature seeds of cultivated plants: kidney bean (Phaseolus vulgaris L.), soybean (Glycine max (L.) Merr.), soft spring wheat (Triticum aestivum L. emend. Fiori et Paol), barley (Hordeum vulgare L.), and oat (Avena sativa L.), and the products of technological processing of grain cultures (floor, bran) was studied. Reliable NAPE identification was performed by a comparison of their chromatographic mobility with the marker NAPE sample from wheat flour and synthetic phosphatidylmethanol, and also using specific reagents. Kidney bean cv. Shchedraya seeds contained the highest amount of NAPEs. In legumes, the content of NAPEs varied not only in different species but also in different cultivars of a single species. In cereals, the highest NAPE content was detected in the barley seeds and best quality wheat flour. The content of NAPEs in cereal seeds was less variable than in legumes. NAPE quantification showed that accumulation of this phospholipid class occurred in parallel with accumulation of total phospholipids in seeds. The relation between NAPE content and the processes of seed development and their lipid composition is discussed. The seeds and products best suitable for NAPE isolation are recommended.     

Inhibition of germination and α-amylase induction by 6-methoxy-2-benzoxazolinone in twelve plant species

6-Methoxy-2-benzoxazolinone (MBOA) inhibited germination of rice (Oryza sativa L.), wheat (Triticum aethiopicum Jakubz), rye (Secale cereale L.), onion (Allium cepa L.), wild oat (Avena fatua L.), barnyard grass [Echinochloa crus-galli (L.) Beauv.], ryegrass (Lolium rigidum Gaudin), cress (Lepidium sativum L.), lettuce (Lactuca sativa L.), tomato (Lycopersicum esculentum Mill.), carrot (Daucus carota L.) and amaranth (Amaranthus retroflexus L) and the inhibition increased with increasing MBOA concentrations. MBOA also inhibited the induction of α-amylase in these plant seeds and the inhibition increased with increasing MBOA concentrations. There were variations in sensitivity of these plant species to MBOA, and species of family Poaceae (barnyard grass, wild oat, rice, rye, ryegrass, and wheat) were less sensitive to MBOA than the other plant species.     

Assessing the Rhizotoxicity of the Aluminate Ion, Al(OH)(4)

Dissolved aluminum (III) in acidic soils or culture media is often rhizotoxic (inhibitory to root elongation). Alkaline solutions of Al are also sometimes rhizotoxic, and for that reason toxicity has been attributed to the aluminate ion, Al(OH)₄⁻. In the present study, seedlings of wheat (Triticum aestivum L. cv Tyler) and red clover (Trifolium pratense L. cv Kenland) were cultured in aerated aluminate solutions at pH 8.0 to 8.9. The bulk phases of these solutions were free of reactive polynuclear hydroxy-Al (including the extremely toxic species AlO₄Al₁₂[OH]₂₄[H₂O]⁷⁺₁₂ [Al₁₃]) according to the ferron (8-hydroxy-7-iodo-5-quinolinesulfonic acid) assay. At an aluminate concentration of 25 micromolar (23 micromolar activity) and a pH of 8, root elongation was less than 40% of Al-free controls, but at pH 8.9 elongation was 100% of controls. The hypothesis is offered that aluminate is nontoxic and that the inhibition at lower pH values is attributable to Al₁₃ postulated to have formed in the acidic free space of the roots where the ratio /{Al³⁺/}//{H⁺/}³ may rise above 10¹⁰. At this value hydroxy-Al in over-saturated, alkaline solutions begins to undergo rapid conversion to polynuclear species.     

Influence of soil solution aluminum on root elongation of wheat seedlings

Wheat (Triticum aestivum L.) seedlings were grown for 4 days in an acid soil horizon treated with 10 levels each of Ca(OH)₂, CaSO₄ and CaCl₂. The treatments resulted in a wide range of Al levels and Al speciation in soil solution. Seedling root length in the Ca(OH)₂ treatments was significantly related (p<0.01) to calculated Al³⁺ activity in soil solution. The Al–SO₄ complex in soil solution had a negligible effect on the root growth of Hart wheat, thus confirming the previously reached conclusion concerning the nonphytotoxicity of Al–SO₄. The short-term seedling root growth technique used in this investigation allowed for separation of Al effects on root elongation from those on plant nutrition and should be useful for studying Al toxicity relationships in soil.     

Effect of sewage water on mineral nutritive potential of six fodder species grown under semiarid conditions

Investigation was performed to assess the effect of different sewage water treatments on the metal status of different fodder species consumed by ruminants under semi-arid conditions. Five samples each of six fodder species viz., Trifolium alexandrinum, Cichorium intybus, Avena sativa, Medicago polymorpha, Brassica campestris and Medicago sativa were collected from three fields irrigated with canal water, mix water (canal water and sewage water) and sewage water, respectively. Fodder samples were analyzed to determine the Mg, Co and Zn concentrations in shoots. Higher values of these metals were found in fodder species irrigated with sewage water relatively. Mg and Zn concentrations in all the fodder species were found to be below the critical level among all treatments. Whereas, concentrations of Co in the different fodder species were significantly different (p < 0.05) and above the critical level. Consequently, ruminants feeding on these fodder species need continued mineral supplementation of Zn and Mg elements to prevent diseases caused by the deficiency of these elements, and to support optimum animal productivity.     

Differential responses of antioxidant enzymes to aluminum toxicity in two rice (Oryza sativa L.) cultivars with marked presence and elevated activity of Fe SOD and enhanced activities of Mn SOD and catalase in aluminum tolerant cultivar

Seedlings of two Indica rice (Oryza sativa L.) cvs. HUR-105 and Vandana, differing in Al-tolerance were used to identify the key mechanisms involved in their differential behaviour towards Al toxicity. Cv. HUR-105 appeared to be Al sensitive by showing significant reduction (p ≤ 0.01) in root/shoot length, fresh weight, dry weight and water content in presence of 421 μM Al³⁺ in growth medium whereas cv. Vandana appeared to be fairly Al³⁺ tolerant. A conspicuous and significant reduction in dry weight of root and shoot was observed in Al sensitive cv. HUR-105 with 178 μM Al³⁺ treatment for 3 days. Al was readily taken up by the roots and transported to shoots in both the rice cultivars. Localization of absorbed Al was always greater in roots than in shoots. Our results of the production of reactive oxygen species (ROS) H₂O₂ and O₂ ^.? and activities of major antioxidant enzymes such as total superoxide dismutase (SOD), Cu/Zn SOD, Mn SOD, Fe SOD, catalase (CAT) and guaiacol peroxidase revealed Al induced higher oxidative stress, greater production of ROS and lesser capacity to scavenge ROS in cv. HUR-105 than Vandana. With Al treatment, higher oxidative stress was noted in shoots than in roots. Greatly enhanced activities of SOD (especially Fe and Mn SOD) and CAT in Al treated seedlings of cv. Vandana suggest the role of these enzymes in Al tolerance. Furthermore, a marked presence of Fe SOD in roots and shoots of the seedlings of Al tolerant cv. Vandana and its significant (p ≤ 0.01) increase in activity due to Al-treatment, appears to be the unique feature of this cultivar and indicates a vital role of Fe SOD in Al-tolerance in rice.     

Effect of various metal ions on growth of two wheat lines known to differ in aluminium tolerance

The effects of aluminium (Al), manganese (Mn), zinc (Zn), copper (Cu), boron (B), iron (Fe), gallium (Ga), scandium (Sc) and lanthanum (La) on growth of an Al-tolerant and an Al-sensitive line of wheat (Triticum aestivum L.) were measured in solution culture. The concentrations of nutrients in the basal nutrient solution were (M) 500 Ca, 100 Mg, 300 K, 600 N (150 NH₄, 450 NO₃), 600 SO₄, 2.5 P, 3 B, 2.5 Fe, 0.5 Zn, 0.5 Mn, 0.1 Cu at a pH of 4.7. The major solution nutrient concentrations were maintained at the nominal concentration with monitoring, frequent additions and weekly renewal. Differentiation in yield between the Al-tolerant and Al-sensitive line only occurred in the presence of Al indicating that, in the long term, none of the other metals tested could be used as an analog for Al. The visual symptoms in the roots of Cu toxicity (in both lines) and Al toxicity (in the sensitive line) were similar. The solution concentration (M) at which yield of the roots of the tolerant line was reduced by 50% was, in order of increasing tolerance, Cu 0.5, Sc 1.1, La 7.1, Ga 8.6, Al 15, Zn 19, Fe 84, B 490 and Mn 600.     

Changes in cereal cultivation during the Iron Age in southern Sweden: a compilation and interpretation of the archaeobotanical material

Macrofossil data from 73 sites dating to the south Swedish Iron Age (500 b.c.–a.d. 1100) have been compiled and analyzed in order to elucidate long term changes in cereal cultivation. The analyses indicate that “permanent field” agriculture was established at the end of the Bronze Age utilizing Hordeum vulgare var vulgare as a primary crop and Triticum aestivum ssp vulgare/compactum, Triticum spelta/dicoccum/monococcum, Avena sativa and Secale cereale as secondary crops. An observed change towards the end of Roman Iron Age (1–a.d. 400) is the expansion of Secale cereale and Avena sativa cultivation. Evidence also suggests that winter sowing of the former commenced at the latest during the eighth, ninth and tenth centuries a.d. The introduction of winter sowing possibly coincided with the establishment of crop rotation agriculture. During most of the Iron Age southern Sweden displays significant regional variations with regards to cereal cultivation practice. There is however evidence that a more homogenous agriculture appeared across the investigated area from the beginning of the Viking Age (a.d. 800–1100) onwards.     

Differential uptake of mercury vapor by gramineous c(3) and c(4) plants

The uptake of mercury vapor by six gramineous plant species was compared under uniform conditions using a whole-plant chamber and ²⁰³Hg-labeled mercury at a low atmospheric concentration. Mean Hg uptake by leaves of the C₃ species oats (Avena sativa), barley (Hordeum vulgare), and wheat (Triticum aestivum) was 5 times greater than that by leaves of the C₄ species corn (Zea mays), sorghum (Sorghum bicolor), and crabgrass (Digitaria sanguinalis). Although there was a difference in resistances associated with vapor entry into the leaves, as shown by estimates of gas exchange, the differential uptake by C₃ and C₄ species was largely attributable to internal resistances to Hg vapor binding. The nature of the internal resistances and the site or sites of Hg vapor binding remain unspecified.     

Male Sterility and Anther Wall Structure in Copper-deficient Plants

Anther development and pollen sterility were followed in plantsof wheat, oat, barley, sweetcorn, sunflower, petunia and subterraneumclover grown at a range of copper supplies. Copper-deficientplants had increased pollen sterility. Lignified wall thickenings were reduced or absent in the endotheciaof anthers from Cu-deficient plants. Reduced seed set may resultboth from reduced pollen fertility or failure of the stomiato rupture due to decreased lignification of anther walls. Triticum aestivum L., wheat, Hordeum vulgare L., barley, Avena sativa L., oat, Zea mays L., corn, sweetcorn, maize, Helianthus annuus L., sunflower, Petunia hybrida L., Trifolium subterraneum L., subterranean clover, male sterility, anther development, copper deficiency