Effect of salinity,alkalinity and iron application on the availability of iron,manganese, phosphorus and sodium in pea (Pisum sativum L.) crop

Summary The effect of the salinity, alkalinity and Fe application on the dry matter yield and availability of Fe, Mn, P and Na were studied in the greenhouse on pea (Pisum sativum L.) crop. The highest dry matter yield was recorded in normal soil which decreased with the increase in the salinity and alkalinity, minimum being at 40 ESP. Alkalinity was more harmful to pea crop than salinity.Fe at 10 ppm increased the dry matter yield significantly. Highest Fe concentration (408.12 ppm) was recorded in 40 ESP soil followed by 20 ESP (395.2 ppm). Salinity alongwith marginal or higher alkalinity reduced harmful effect of alkalinity. The uptake of Fe was the highest in normal soil due to the high dry matter yield. All the three sources increased the concentration of Fe and its uptake than the control in all the soils but did not show much distinction among themselves.The concentration of Mn decreased more with the increase in alkalinity than salinity but salinity with alkalinity improved Mn concentration. Similarly uptake of Mn also decreased sharply with the increase in salinity and alkalinity. The application of Fe sources decreased Mn concentration but increased the uptake. The highest decrease was caused with FeSO₄ and lowest with Fe rayplex.Like Mn the concentration and uptake of P decreased with the increased levels of salinity and alkalinity. The addition of Fe decreased the concentration of P, highest depression being with Fe KE-MIN.Increase in ESP increased the concentration and the uptake of Na greatly. Addition of Fe through all the sources increased Na concentration and uptake significantly but sources did not differ much in their effect on Na.     

Influence of age, sex, and sexual activity on trace element levels and antioxidant enzyme activities in field mice (Apodemus sylvaticus and Mus spretus)

The influence of age, gender and sexual activity on both hepatic levels of some trace elements (Fe, Cu, Zn, Mn, Se) and the activities of glutathione-S-transferase (GST) and superoxide dismutase (SOD) was investigated in Wood mice (Apodemus sylvaticus) and Algerian mice (Mus spretus). Animals were taken from a riverside community of an unpolluted area of central Portugal. Adult A. sylvaticus presented the highest hepatic mean concentrations of Cu and Mn, whereas adult M. spretus had the highest Fe concentration in the liver. Moreover, an influence of age on the contents of Fe, Zn, and Mn has been observed in A. sylvaticus, whereas in M. spretus an influence of gender and sexual activity was only detected on Zn levels. In contrast, enzyme activities were not influenced by the studied variables, despite a tendency for an increase in SOD activity in sexually active M. spretus. GST activity was species dependent, whereas SOD activity was similar between species. These findings were analyzed regarding the relationship of both essential trace elements and the two antioxidant enzymes with physiological and metabolic pathways related to life cycles in the two species of mice. Results enhanced the understanding of A. sylvaticus and M. spretus as biological models, allowing their future use as bioindicators of environmental toxicity.     

Persistent alterations in biomarkers of oxidative stress resulting from combined in Utero and neonatal manganese inhalation

Neonatal female and male rats were exposed to airborne manganese sulfate (MnSO₄) during gestation and postnatal d 1–18. Three weeks post-exposure, rats were killed and we assessed biochemical end points indicative of oxidative stress in five brain regions: cerebellum, hippocampus, hypothalamus, olfactory bulb, and striatum. Glutamine synthetase (GS) protein levels, metallothionein (MT) and GS mRNA levels, and total glutathione (GSH) levels were determined for all five regions. Overall, there was a statistically significant effect of manganese exposure on decreasing brain GS protein levels (p=0.0061), although only the highest dose of manganese (1 mg Mn/m³) caused a significant increase in GS messenger RNA (mRNA) in both the hypothalamus and olfactory bulb of male rats and a significant decrease in GS mRNA in the striatum of female rats. This highest dose of manganese had no effect on MT mRNA in either males or females; however, the lowest dose (0.05 mg Mn/m³) decreased MT mRNA in the hippocampus, hypothalamus, and striatum in males. The median dose (0.5 mg Mn/m³) led to decreased MT mRNA in the hippocampus and hypothalamus of the males and olfactory bulb of the females. Overall, manganese exposure did not affect total GSH levels, a finding that is contrary to those in our previous studies. Only the cerebellum of manganese-exposed young male rats showed a significant reduction (p<0.05) in total GSH levels compared to control levels. These data reveal that alterations in biomarkers of oxidative stress resulting from in utero and neonatal exposures of airborne managanese remain despite 3 wk of recovery; however, it is important to note that the doses of manganese utilized represent levels that are 100-fold to a 1000-fold higher than the inhalation reference concentration set by the US Environmental Protection Agency.     

Effects of simulated acid precipitation on the cycling of manganese under Sitka spruce (Picea sitchensis)

Simulated acid rain at pH 3.3, 4.3 and 5.3 has been applied by overheadspraying to reconstructed soil profiles and young Sitka spruce (Piceasitchensis) trees in pots to assess the effect of rainfall acidityonthe fate and recycling efficiency of Mn from ⁵⁴Mn-labelled Sitkaspruce litter. The concentration of ⁵⁴Mn in throughfall wassignificantly increased by acidification of the rain, but ⁵⁴Mnactivity in drainage water remained low and was not significantly affected. Thefact that only < 1.5% of ⁵⁴Mn was lost in drainage water suggeststhat forest ecosystems efficiently retain Mn, at least in the short term. Thebulk of ⁵⁴Mn (approximately 60 to 70%) was retained in the litterlayer. Compared with rain at pH 4.3, rain at pH 3.3 acidified L/F and H/Ahorizon soils. The amount of ⁵⁴Mn found in the different soilhorizons was only influenced significantly by rainfall acidity in the E horizonsoil, however, where ⁵⁴Mn activity was increased by the most acidtreatment. The activity of ⁵⁴Mn in Sitka spruce needles did notdiffer significantly with treatments.     

Effects of micronutrients on the growth form of two families of Pinus radiata (D.Don) seedlings

Micro-element deficiencies have been implicated in the development of poor stem form in Pinus radiata plantations. Cu, Mn and B have been implicated in previous studies as influencing tree form and/or the process of lignification in plants. Therefore an experiment was initiated to examine the individual and interactive effects exhibited by these trace elements on stem form and lignification.The investigation showed that Cu deficiency reduced both lignification and stem form in seedlings. Mn, competing with Cu for uptake, enhanced the symptoms of Cu deficiency. Boron addition did not alleviate the expression of deformity or increase levels of lignification. There was a clear family influence on the development of seedling stem form in response to variations in mineral nutrition.     

Interaction between the root-lesion nematode Pratylenchus vulnus and the mycorrhizal association of Glomus intraradices and Santa Lucia 64 cherry rootstock

The effects of the interaction between Pratylenchus vulnus and the endomycorrhizal fungus Glomus intraradices on growth and nutrition of Santa Lucia 64 cherry rootstock was studied under microplot conditions during one growing season. Fresh top weight, and stem diameter of mycorrhizal plants and high P treatments with and without P. vulnus were significantly higher than those of non-mycorrhizal plants. The lowest shoot length and fresh root weights were recorded in nematode inoculated plants in low P soil. Mycorrhizal infection did not affect the number of nematodes per gram of root in plants infected with P. vulnus. In the presence of the nematode, internal spore production by G. intraradices was significantly reduced. No nutrient deficiencies were detected through foliar analysis, although low levels of Ca, Mn and Fe were detected in nematode treatments. Mycorrhizal plants achieved the highest values for N, P, S, Fe, and Zn, whereas high P treatments increased absorption of Ca and Mn. Early mycorrhizal infection of Santa Lucia 64 cherry rootstock by G. intraradices confers increased growth capacity in the presence of P. vulnus.     

Functional associations between the metabolome and manganese tolerance in Vigna unguiculata

Genotypic- and silicon (Si)-mediated differences in manganese (Mn) tolerance of cowpea (Vigna unguiculata) arise from a combination of symplastic and apoplastic traits. A detailed metabolomic inspection could help to identify functional associations between genotype- and Si-mediated Mn tolerance and metabolism. Two cowpea genotypes differing in Mn tolerance (TVu 91, Mn sensitive; TVu 1987, Mn tolerant) were subjected to differential Mn and Si treatments. Gas chromatography-mass spectrometry (GC-MS)-based metabolite profiling of leaf material was performed. Detailed evaluation of the response of metabolites was combined with gene expression and physiological analyses. After 2 d of 50 μM Mn supply TVu 91 expressed toxicity symptoms first in the form of brown spots on the second oldest trifoliate leaves. Silicon treatment suppressed symptom development in TVu 91. Despite higher concentrations of Mn in leaves of TVu 1987 compared with TVu 91, the tolerant genotype did not show symptoms. From sample cluster formation as identified by independent component analysis (ICA) of metabolite profiles it is concluded that genotypic differences accounted for the highest impact on variation in metabolite pools, followed by Mn and Si treatments in one of two experiments. Analysis of individual metabolites corroborated a comparable minor role for Mn and Si treatments in the modulation of individual metabolites. Mapping individual metabolites differing significantly between genotypes onto biosynthetic pathways and gene expression studies on the corresponding pathways suggest that genotypic Mn tolerance is a consequence of differences (i) in the apoplastic binding capacity; (ii) in the capability to maintain a high antioxidative state; and (iii) in the activity of shikimate and phenylpropanoid metabolism.     

Screening sorghum for tolerance to excess manganese in solution culture

This study was conducted to define traits to screen sorghum (Sorghum bicolor L. Moench) genotypes for tolerance to excess Mn. Visual Mn toxicity symptoms, net and total root lengths, shoot and root dry matter yields, and shoot and root Mn concentrations were determined for plants grown in nutrient solutions (pH 4.5) at different levels of Mn (0, 3, 6, 9 and 12 mM above the initial 18 M) to assess plant responses to excess Mn. Dry matter yields showed greatest variability among genotypes, and was an effective trait to evaluate sorghum for tolerance to excess Mn. Reductions in dry matter yields did not occur until Mn levels were above 3 mM. Levels of Mn between 3 and 6 mM could effectively be used to screen sorghum for genotypic differences to excess Mn. Manganese levels above 6 mM were too severe to allow good genotypic differentiation. Of genotypes tested, NB9040 and Wheatland showed good tolerance and SC283 and ICA-Nataima were sensitive to excess Mn.     

A culture unit system for the study of responses of mycorrhizal and non-mycorrhizal seedling to treatments

The time-dependence of Mn accumulation was confirmed in potato foliage (Solanum tuberosum. L.cv. Norland) grown in solution culture. Older leaves grown at 0.61 mM Mn had substantially higher Mn concentrations than younger leaves and stem samples. Levels of Mn in older leaves increased steadily from 4000 µg g^–1 at one week to 8–10,000 µg g^–1 at 6 weeks, but were relatively constant in the emerging leaves. Even foliage grown at low Mn levels (0.01 mM Mn) had 4 fold gradients in Mn concentration from younger (40 µg g^–1) to older leaves (180 µg g^–1).At 0.61 mM Mn, concentrations of 3–4000 µg g^–1 in the youngest fully-developed leaves did not bring about any decline in yield, and levels of up to 5000 µg g^–1 occurred in individual potato leaves before Mn toxicity symptoms were observed. Potato foliage grown at the high Mn had similar leaf numbers, but showed an increased stem length and smaller leaves than foliage grown at 0.01 mM Mn. In particular, the leaf area of the middle and lower leaf fractions were affected by the high Mn level.The ability of rapidly growing plants to withstand high concentrations of Mn is discussed in relation to the pattern of dry matter and Mn accumulation shown by potato foliage.     

Elemental concentrations in plant tissues as influenced by low pH soils

Summary Soils influenced by acid mine drainage (pH<5.0) are characterized by low concentrations of essential nutrients and increased solubility of heavy metals. The conditions typically reduce plant establishment and growth. However, river birch (Betula nigra L.) is commonly found along low pH streams in southeastern Ohio. The objective of this study was to determine the concentration of Al, Mn, Ca and Mg inB. nigra tissues.The results indicate Al and Mn are accumulating inB. nigra when compared to other species. Within river birch, Al concentrations are highest in roots; Mn concentrations are highest in leaves. There is not a concomitant reduction in Ca and Mg concentrations as suggested by soil levels.     

Effect of Na/Ca and Na/K ratios in saline culture solution on the growth and mineral nutrition of rice (Oryza sativa L.)

Summary A study was conducted to evaluate the effect of manganese on accumulation of Zn, Fe, Cu, and B by different soybean genotypes under varying soil pH conditions, in view of determining tolerance towards extremes in soil pH and mineral toxicities. Enon sandy loam soil was used for the investigation in a greenhouse. Manganese rates were 0, 10, and 20 kg/ha. The pH levels were 5.3, 6.3, and 7.0. The soybean genotypes tested were PI 159319, PI 324924, PI 960895, and L-76-0132. Results indicate that Zn concentration in the genotypes leaf and seed was not affected by Mn application whereas the Cu concentration in the leaf was affected. In general, there was an increase in concentration of Fe in the genotypes seed with Mn application. Boron concentration in the genotypes leaf and seed was unaffected by Mn application. The effect of soil pH on Zn, Fe, Cu, and B in the genotypes tissue was significant. This did not result in toxic levels of the elements in the tissues.Contribution of the Department of Plant Science and Technology, North Carolina Agricultural and Technical State University, Greensboro, N.C. 27411, and Agronomic Division, North Carolina Department of Agriculture, Raleigh, NC 27611, USA     

Aluminum,Fe, Ca,Mg, K,Mn, Cu,Zn and P in above- and belowground biomass. I.Abies amabilis andTsuga mertensiana

In a mature mixed subalpine stand ofTsuga mertensiana andAbies amabilis, significantly higher Al levels were found in foliage, branch and root tissues ofT. mertensiana.Tsuga mertensiana had significant increases in Al, Ca and Mn levels with increasing foliage age. In current foliage,T. mertensiana had lower levels of Ca, similar levels of Mg and P, and higher levels of Mn thanA. amabilis. Both tree species had Cu and Fe present at higher levels in branch than foliage tissues. Fine roots had the highest concentrations of Al, Fe and Cu but the lowest Ca and Mn concentrations of all tissues analyzed. In the roots of both species, phloem tissues always had significantly higher Al levels than xylem. Fine roots (< 1 and 1–2 mm) ofT. mertensiana had higher Al levels than were found inA. amabilis. Roots greater than 2 mm in diameter exhibited no significant differences in Al levels in phloem or xylem tissue betweenA. amabilis andT. mertensiana. The two species show a clear difference in their ability to accumulate specific elements from the soil.     

Metal metabolism in the red alga Cyanidium caldarium and its relationship to metal tolerance

The unicellular red alga Cyanidium caldarium is tolerant to high levels of various metal ions. Cells of this alga cultured with divalent metal ions at 5 mM contained an elevated concentration of each metal, with the highest level for Zn followed by Mn > Ni > Cu. This order is in fair agreement with the toxicity levels reported previously, with the exception of Mn, which shows a toxicity level comparable to that of Ni. Transmission electron microscopy indicated the presence of electron-dense bodies in the algal cells, and elemental analysis by energy dispersive X-ray spectrometry showed high levels of Fe and P in these bodies. Accumulation of Zn was found in these particles in Zn-treated algal cells, whereas no such deposition was found for Cu, Ni, or Mn in cells treated with the respective metals. Although trapping of Zn in the intracellular bodies may contribute to reduction of metal activity in the cells, this effect can be overcome by high intracellular levels of Zn that result in a high degree of toxicity. The correlation between intracellular concentration and toxic levels of metal ions implies that the reduced incorporation of the metals is a major detoxification mechanism in this alga.     

Subcellular localization of mineral deposits in the roots of wheat (Triticum aestivum L.)

Summary Mineral distribution in the roots of wheat (Triticum aestivum L. cv. Wheaton) was investigated using X-ray microanalysis of bulk frozen hydrated roots in SEM and of freeze substituted sections in TEM. Results obtained using the two methods agreed reasonably well. A total often elements were detected: Na, Mg, Si, P, S, Cl, K, Ca, Mn, and Fe. Of these Si, P, Ca, and Mn were incorporated into biomineralized structures. Silica was deposited in the endodermal walls in the older parts of the root. Silicon was also detected in the large central metaxylem lumina in the basal zone of the root, and in the smaller peripheral metaxylem and the immediately contiguous pericycle and outer parenchyma cells bridging the small metaxylem vessels to the endodermal layer. In the basal zone of the root some of the inner cortical cells contained intracellular electron opaque deposits. These were associated with the cell walls, had non-opaque inclusions and microanalysis revealed that they consisted of calcium, phosphorus and manganese.Abbreviations A apical zone of root - M midzone of root - B basal zone of root - SEM scanning electron microscope - TEM transmission electron microscope     

Increased tolerance to the root-lesion nematode Pratylenchus vulnus in mycorrhizal micropropagated BA-29 quince rootstock

The interaction between Glomus intraradices and the root-lesion nematode Pratylenchus vulnus was studied on micropropagated BA-29 quince rootstock during one growing season. Inoculation with G. intraradices significantly increased growth of plants in low P soil and was more effective than P fertilization at increasing top-plant development. In the presence of the nematode, mycorrhizal plants achieved higher values in all growth parameters measured. P. vulnus caused a significant decrease in the percentage of root length colonized by G. intraradices and fewer internal vesicles were formed within the host roots. Enhanced root mass production accounted for the twofold increase in final nematode population recovered from plants with combined inoculations of pathogen and symbiont. Low levels were found of Al, Fe, Mn and Zn in nonmycorrhizal nematode-infected plants in low P soil. G. intraradices-inoculated plants reached the highest foliar levels of N, Ca, Mg, Mn, Cu and Zn. Mycorrhizal plants infected with P. vulnus maintained normal to high levels of Mn, Cu, and Zn. Inoculation with G. intraradices favours quince growth and confers protection against P. vulnus by improving plant nutrition.     

Manganese and iron interactions on their uptake and distribution in soybean (Glycine max (L.) Merr.)

Summary The uptake and distribution of iron and manganese were studied in a manganese-sensitive soybean cultivar (‘Bragg’) grown over a range of supply levels of these nutrients in solution culture. At high (90 and 275 μM) manganese levels, increasing the iron concentration in solution from 2 to 100 μM partially overcame the effects of manganese toxicity. Interactions between manganese and iron occurred for dry matter yields, rate of Mn absorption by the roots, and the proportions of manganese and iron transported to the tops. No interaction was observed for the rate of root absorption of iron. The percentage distribution of manganese in the plant top increased with increasing iron, despite a reduced rate of Mn uptake. On the other hand, iron uptake was independent of solution Mn concentration and increased with increasing solution Fe. Also more iron was retained in the roots at high Mn and/or Fe levels in solution. Concentrations of manganese and iron in roots, stems and individual leaves were affected independently by the manganese and iron supplyi.e. without any interaction occurring between the two elements. In general, the concentration in a plant part was related directly to the solution concentration. Symptoms resembling iron deficiency correlated poorly with leaf Fe concentrations whereas high levels of manganese were found in leaves displaying Mn toxicity symptoms.     

Developmental changes affected by Mn deficiency

The changes in tissue Mn, Cu, Fe, Zn, and Superoxide dismutase (SOD) activity were studied in control and Mn-deficient mice during postnatal development. Mn levels were lower in tissues from Mn-deficient mice than in controls throughout development. By day 60, Mn concentration in tissues from Mn-deficient mice was at least 70% lower than that of controls. Cu levels in the two groups did not differ appreciably. Liver Cu concentration was highest at day 5, then decreased. Heart and kidney Cu increased throughout development. Fe concentration in heart and liver was similar in both groups at 1, 5, and 20 days of age, but at day 60, kidney Fe in the Mn-deficient mice was 40% higher than in controls. The developmental pattern for MnSOD activity paralleled that of Mn concentration. At day 5, there were no differences in MnSOD activity between control and deficient mice. By day 60, MnSOD activity in most tissues was at least 50% lower than that of controls, possibly increasing the susceptibility of the Mn deficient animal to oxidative damage. These developmental patterns should help investigators to determine the tissues and time periods in which to study trace element metabolism.     

A comparative study on the influence of manganese on the bactericidal response of marine invertebrates

Manganese, Mn, is a naturally abundant metal in marine sediments. During hypoxic conditions the metal converts into a bioavailable state and can reach levels that have been shown immunotoxic to the crustacean Nephrops norvegicus. For this species it has previously been shown that exposure to 15 mg L⁻¹ of Mn decreased the number of circulating haemocytes while it for the echinoderm Asterias rubens increased the number of coelomocytes. Here, we compared if five days of exposure to the same concentration of Mn affects the bactericidal capacity of these two species and the mollusc Mytilus edulis when inoculated with the bacterium Vibrio parahaemolyticus. Viable counts of the bacteria were investigated at a time-course post-injection in the blood and the digestive glands of Mn-exposed and un-exposed (controls) animals. Accumulation of Mn was also analyzed in these tissues. When exposed to Mn the haemocyte numbers were significantly reduced in M. edulis and it was shown that the bactericidal capacity was impaired in the mussels as well as in N. norvegicus. This was most obvious in the digestive glands. These two species also showed the highest accumulation of the metal. In A. rubens the bactericidal capacity was not affected and the metal concentration was similar to the exposure concentration. After a recovery period of three days the concentration of Mn was significantly reduced in all three species. However, in M. edulis and N. norvegicus it was still double that of A. rubens which could explain the remaining bactericidal suppression observed in N. norvegicus. This study pointed out that exposure to such Mn-levels that are realistic to find in nature could have effects on the whole organism level, in terms of susceptibility to infections. The effect seemed associated to the accumulated concentration of Mn which differed on species level.