Håkan Asp

Swedish University of Agricultural Sciences, Uppsala, Uppsala, Sweden

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Publications (23)48.03 Total impact

  • BIT´s 2nd Annual World Congress of Agricultural Biotechnology, Dalian, China, 20-22 Sep 2012; 09/2012
  • Rapport 2011:6. 01/2011;
  • Acta horticulturae 01/2009; 832.
  • Malgorzata Michalska, Håkan Asp
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    ABSTRACT: The uptake of cadmium and lead by three lettuce (Lactuca sativa L.) cultivars was studied in water culture experiment. Different amounts of cadmium (Cd) and leaf (Pb) were added to the nutrient solution (0; 0.05 μM Cd; 0.5 μM Cd; 0.05 μM Pb; 0.5 μM Pb; 0.5 μM Cd together with 0.5 μM Pb). Fresh and dry matter yield of leaves and roots were significantly reduced by the presence of 0.5 μM Cd and 0.5 μM Cd together with 0.5 μM Pb. The higher the Cd or Pb concentration in solution the more Cd and Pb accumulated in the plants. Most of the accumulated heavy metals were located in the roots. The combination of Cd and Pb in the nutrient solution had an additive effect on most investigated parameters. The presence of lead alone, almost in all cases, did not effect the concentration of macro- and microelements. Cadmium in concentration 0.5 μM Cd and Cd together with Pb caused a significant increase of the Ca and Cu contents in shoot content of Pb. Roxette accumulated the least Pb in the roots at 0.5 μM Pb whereas Pia the least when both Cd and Pb were present in the solution.
    Communications in Soil Science and Plant Analysis 08/2006; 32(3&4)(571–583 (2001)):571-583. · 0.42 Impact Factor
  • P. Stolt, H. Asp, S. Hultin
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    ABSTRACT: Cadmium (Cd) accumulation in wheat genotypes of spring bread wheat (Triticum aestivum L.) and spring durum wheat (Triticum turgidum var. durum) was studied in field trials every third week throughout the growing season. The study was carried out in Sweden on three different soils and during two growing seasons. The results showed that the genetic variation in shoot and grain Cd accumulation remained consistent, regardless of soil type or growing season. In addition, it was possible to select the genotype that accumulated most Cd already at the beginning of the growing season, since this genotype also accumulated most Cd in the vegetative tissues of the shoot. These results indicate that it is possible to identify genotypes that accumulate most Cd in the grain at an early plant development stage. High Cd concentrations in the shoot were also observed to give high Cd concentrations in the grain. This indicates that the regulatory mechanism for grain Cd accumulation is not located in the shoot, but in the root or as a feature of root Cd uptake. The soil material and the soil solution at all three sites were analysed for strongly bound Cd (as extracted with 2 m HNO3), more easily plant-available Cd (as extracted with ammonium lactate), pH, organic matter, clay content and conductivity. None of these parameters was clearly correlated to the Cd concentration in the grain.
    Journal of Agronomy and Crop Science 05/2006; 192(3):201 - 208. · 2.62 Impact Factor
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    ABSTRACT: The effects of AICI3 on uptake of Ca2+ and phosphate in roots of intact beech (Fagus sylvatica L. provenance Maramures) plants were studied in nutrient solution and soil solution. Aluminium reduced the concentrations of Ca, Mg and P in plants and increased that of K. In short term experiments, uptake of Ca2+(45Ca) was reduced by exposure of the roots to Al. The effect of aluminium on Ca2+(45Ca) uptake was immediate and primarily of a competitive nature, preventing Ca2+ from being adsorbed. Uptake of 32P-phosphate increased with increasing Al concentration up to 0.1 mM and then decreased at higher Al concentrations. The effect of Al on 32P-phosphate uptake was most pronounced during the first hours of exposure. Growth of plants for 15 days in soil solution, collected from the upper A horizon of a beech forest soil, had no effect on uptake of Ca2+(45Ca) and 32P-phosphate, probably because of a low concentration of labile bound monomeric Al and binding of Al to organic compounds. Soil solution from the deeper B horizon reduced Ca2+(45Ca) uptake and increased 32P-phosphate uptake in a manner similar to that with Altreatment in nutrient solution. It is concluded that in soil solution from the deeper regions of the soil, mineral uptake by roots was affected by Al.
    Physiologia Plantarum 04/2006; 74(2):299 - 305. · 3.66 Impact Factor
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    ABSTRACT: Effects of copper on fine root geometry (number, length) and K and Cu content in birch (Betula pendula Roth) were studied. After pre-cultivation, the plants were grown in a nutrient film technique (NFT) system and exposed to additional 0–5 μM for a period of 8 days. The NFT system permitted undisturbed growth of the roots during monitoring. Copper experiments were carried out in a split-root setup both with a uniform and differentiated Cu supply to investigate growth responses of roots grown in a homogeneous and heterogeneous root environment, respectively. At uniform external Cu supply, average root length was affected by increased Cu concentration during the first four days while the next four days only the overall root length (product of root length and root number) was significantly reduced. During the first four days in the split-root experiments with differentiated Cu supply, additional Cu primarily reduced root number on the Cu-treated parts of the root system but at stronger Cu concentration the overall root length was also significantly reduced. In contrast, number and average root length of the part of the root system not exposed to Cu increased when 1, 2 and 5 μM Cu was added to the other side. Growth parameters were affected differently in the beginning of the heavy metal exposure compared to later stages of exposure, which may indicate acclimatisation to Cu stress.
    Physiologia Plantarum 04/2006; 99(3):379 - 384. · 3.66 Impact Factor
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    ABSTRACT: Beech plants (Fagus sylvatica L. provenance Maramures) were grown in nutrient solution at low pH (4.2) and exposed to different concentrations of AlCl3. Uptake and leakage of Ca2+(45Ca2+) and H2PO4-(32P) were studied. A high external aluminium concentration (1.0mM) reduced the uptake and export to the shoot of both calcium and phosphate, while 0.1 mM Al increased the phosphorus level in the roots. To determine the impact of aluminium on the localization of calcium and phosphate, leakage of the elements from both intact plants and plants frozen prior to the leakage experiment was studied. The leakage of Ca2+ from intact plants was not affected by prior exposure to 0.1 mM Al. Freezing of the beech plants before the leakage experiment increased leakage of calcium slightly more from roots of control plants than for roots exposed to 0.1 mM Al, indicating that even low concentrations of alminium may impede the influx of calcium across the plasma membrane in the roots. The patterns of Ca2+ leakage from roots previously exposed to 1.0 mM Al indicated that very little Ca2+ was located extracellularly. The extracellular fraction of phosphate increased with increasing Al concentration in the nutrient solution. Low Al concentration (0.1 mM) only reduced the intracellular phosphate concentration to a minor extent, while 1.0 mM Al profoundly decreased it. It is concluded that 0.1 mM AlCl3 has a limited effect upon the localization of Ca2+ and phosphate in the roots. At higher levels of Al, 0.1–1.0 mM, there is a more dramatic change in nutrient localization in the free space and uptake over the plasma membrane.
    Physiologia Plantarum 04/2006; 83(1):41 - 46. · 3.66 Impact Factor
  • Håkan Asp, Dan Berggren
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    ABSTRACT: In the present study we examine the effects of Al on the uptake of Ca2+ and H2PO-4 in beech (Fagus sylvatica L.) grown in inorganic nutrient solutions and nutrient solutions supplied with natural fulvic acids (FA). All the solutions used were chemically well characterized. The uptake of Al by roots of intact plants exposed to solutions containing 0, 0.15 or 0.3 mM AlCl3 for 24 h, was significantly less if FA (300 mg l−1) were also present in the solutions. The Ca2+(45Ca2+) uptake was less affected by Al in solutions supplied with FA than in solutions without FA. There was a strong negative correlation between the Al and Ca2+ uptake (r2=0.98). When the Al and Ca2+ (45Ca2+) uptake were plotted as a function of the Al3+ activity (or concentration of inorganic mononuclear Al), almost the same response curves were obtained for the -FA and +FA treatments. We conclude that FA-complexed Al was not available for root uptake and therefore could not affect the Ca2+ uptake. The competitive effect of Al on the Ca2+ uptake was also shown in a 5-week cultivation experiment, where the Ca concentration in shoots decreased at an AlCl3 concentration of 0.3 mM. The effect of Al on H2PO−4 uptake was more complex. The P content in roots and shoots was not significantly affected, compared with the control, by cultivation for 5 weeks in a solution supplied with 0.3 mM AlCl3, despite a reduction of the H2PO−4 concentration in the nutrient solution to about one-tenth. At this concentration Al obviously had a positive effect on H2PO−4 uptake. The presence of FA decreased 32P-phosphate uptake by more than 60% during 24 h, and the addition of 0.15 or 0.3 mM AlCl3 to these solutions did not alter the uptake of 32P-phosphate.
    Physiologia Plantarum 04/2006; 80(2):307 - 314. · 3.66 Impact Factor
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    ABSTRACT: The effect of aluminium on plasma membrane-bound enzymes and ion uptake was studied with spruce cuttings (Piccu abies Karst.) grown in nutrient solution, pH 4.2, for 5 weeks. The H+– ATPase and glucan synthase II activities of isolated root plasma membranes were inhibited by the presence of aluminium during growth (0.1–3 mM), with glucan synthase II being more sensitive than the ATPase. The active K+-uptake obtained with intact roots was also inhibited by aluminium, whereas the passive uptake was stimulated ca 4-fold by moderate amounts of aluminium (0.1 mM). The uptake of Ca2+ (passive) was severely inhibited at all external aluminium concentrations tested. Experiments were also performed with aluminium added during the assay, or in preincubations of isolated plasma membranes. Again, the glucan synthuse II activity was severely inhibited bv aluminium. There were no signs of adaptation, i.e., the activities with plasma membranes from cuttings given aluminium during growth, were equally sensitive as the control. The aluminium additions in vitro were at pH 6.5 (ATPase) or 7.2? (glucan synthase II) indicating that lor the enzymes studied, aluminium can be toxic although the pH is neutral.
    Physiologia Plantarum 04/2006; 92(3):459 - 466. · 3.66 Impact Factor
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    ABSTRACT: Phenolic acids—excreted both as root exudates and by microorganisms—are of interest in cultivation systems of different horticultural crops since they have been claimed to accumulate in closed hydroponic growing systems. The aim of the present investigation was to assess the phytotoxic effects when hydroponically grown tomato plants are exposed to phenolic acids in the root environment. The tomato plants were grown in static aerated culture and exposed to benzoic, caffeic, chlorogenic, ferulic, p-hydroxybenzoic, salicylic and vanillic acid at concentrations of 50, 100, 150, 200 and 400 μM in the fresh nutrient solution. The highest concentration of all tested compounds significantly reduced fresh and dry weights. Salicylic and ferulic acid affected plants already at 150 and 200 μM while effects were less pronounced for p-hydroxybenzoic and chlorogenic acid. Chlorophyll fluorescence analysis did not result in any significant difference between any of the tested acids or concentrations. No clear dose-related pattern was obtained with respect to number of leaves and plant length. Visual assessment showed that the most deleterious effects appeared on the roots, which were discoloured and/or had slimy coatings when exposed to the phenolic acids. The uptake of several mineral nutrients was influenced at the highest concentration of all studied compounds. Significantly more bacteria were enumerated in the nutrient solution treated with phenolic acids compared to the controls. Most of the phenolic acids were degraded after 2 days during the start of the trial and within 1 day at the end of the trial. Concentrations phytotoxic to small tomato plants were 1000-fold higher than the natural concentrations measured before. Instead of potentially harmful, the relevance of certain phenolic acids as antimicrobial substances should be considered.
    Scientia Horticulturae. 01/2004;
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    ABSTRACT: In order to test the potential effect of prior exposure to different Cd concentrations on Cd uptake and accumulation, plants of Arabidopsis thaliana, including a phytochelatin-deficient mutant, cad1-3, and the wild type, were compared. For Cd uptake experiments, plants were grown for 1 week in nutrient solution containing different Cd concentrations (0, 0.05, 0.1, 0.25, 0.5, and 1.0 microM Cd(NO(3))(2)). Thereafter they were subjected to 0.5 microM Cd labelled with (109)Cd for 2 h. Uptake experiments with (109)Cd showed that the phytochelatin-deficient mutant cad1-3, accumulated less Cd than the wild type. Both a lower proportion and lower total amount of absorbed Cd were translocated to the shoot in cad1-3 plants compared to wild-type plants. Cadmium exposure also influenced the amounts of nutrients found, whereby after exposure to high Cd concentrations (0.5, 1.0 microM) during growth, cad1-3 roots contained less Fe, K, Mg, P, and S compared to roots of the wild type. In cad1-3 these elements decreased with increasing Cd concentration. The total Cd content in roots and shoots increased significantly with increasing Cd concentration during growth, although the increase was much less in cad1-3 plants. In time-dependent experiments of Cd uptake carried out between 15 and 120 min on plants not previously exposed to Cd, no significant difference in Cd accumulation between the mutant and wild type were found, although a smaller amount of Cd was translocated to the shoot in cad1-3 plants. The possibility that the differences in Cd accumulation in mutant and wild-type lines may be due to the cytosolic Cd regulation, which is inhibited by the complexation of Cd by phytochelatins, is discussed.
    Journal of Experimental Botany 04/2002; 53(368):447-53. · 5.79 Impact Factor
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    ABSTRACT: Plants are most often exposed to multiple environmental stress, rather than single stress phenomena. Therefore, the aim of this study was to investigate plant response to two potential stress factors. We also wished to determine whether one of the stress factors would be dominant, and to assess the outcome in terms of the importance for plant survival. Arabidopsis thaliana L. plants were subjected to both enhanced levels of cadmium (Cd) and ultraviolet-B (UV-B, 280–315 nm) radiation. Wild type plants and a phytochelatin (PC)-deficient mutant, cad1-3, were used. To assess the contribution of Cd and/or UV-B to plant stress, chlorophyll fluorescence, oxygen (O 2 ) evolution, pigment content and Cd and nutrient content were measured. Cadmium inhibited O2 evolution at irradiances above growth light in both wild type and cad1-3. In the latter, photochemical yield (Φp ) was lowered by Cd, and was accompanied by a decreased and light-independent non-photochemical quenching (NPQ), whereas UV-B radiation did not influence these parameters when applied alone. In combination with Cd, UV-B radiation resulted in no detectable change as compared with results with only Cd exposure. The effect of Cd on the content of essential nutrients was analysed by inductively coupled plasma emission (ICP), which showed that Cd and zinc (Zn) were significantly lower in both the root and shoot of cad1-3, compared with the wild type. In roots, the content of potassium (K), magnesium (Mg) and sulfur (S) was significantly lower in cad1-3 than in wild type, whereas Cd or Cd + UV resulted in higher calcium (Ca) amounts in cad1-3. Compared with Cd alone, the Cd + UV treatment reduced the content of Ca in wild type roots. Supplemental UV-B radiation decreased the content of Mg and S; otherwise Cd was the stronger stress factor, generally overriding the sometimes stimulatory effect of the UV-B radiation.
    Functional Plant Biology 07/2001; 28(6):505-512. · 2.57 Impact Factor
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    ABSTRACT: photochemical quenching (q NPQ ) was measured using a pulse amplitude modulated fluorometer. The q NPQ The possible interaction of two stresses, UV-B radi- increased with increasing Cd, while the combination ation and cadmium, applied simultaneously, was of cadmium and UV-B reduced the q NPQ compared to investigated in Brassica napus L. cv. Paroll with that in plants exposed only to cadmium or UV-B radi- respect to chlorophyll fluorescence, growth and ation. The chlorophyll a5b ratio showed a reduction uptake of selected elements. Plants were grown in with UV-B at no or low Cd concentrations (0 mM, 0.5 mM nutrient solution containing CdCl 2 , (0, 0.5, 2 or 5 mM) CdCl 2 ), but not at the higher Cd concentrations used and irradiated with photosynthetically active radiation (2 mM, 5 mM CdCl 2 ). Thus in some instances there
    Journal of Experimental Botany 06/1998; 49(323):1031-1039. · 5.79 Impact Factor
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    ABSTRACT: Binding of Cd to non-specific metal-binding peptides (phytochelatins) in birch roots has been suggested as an explanation for tolerance to Cd toxicity in birch ( Betula pendula ). In the present study, the tolerance of birch roots to Cd was further investigated by using buthionine sulphoximine (BSO) as an inhibitor of phytochelatin synthesis. Birch seedlings, grown in nutrient solution at pH 4.2, were exposed to 0 or 2 μM CdCl 2 combined with 0 or 0.1 mM BSO for 6 d. Plant growth (fresh weight increase and shoot to root dry weight ratio) and the nutrient composition in fine roots, whole roots and shoots were determined. The effects of Cd on growth confirms the results of earlier studies on birch, suggesting a reduced shoot growth, but preserved or stimulated root growth. When Cd and BSO were combined, overall plant growth was severely reduced. BSO was also shown to aggravate Cd-induced reductions of root and shoot concentrations of K, Ca and Mg but to impede the accumulation of Cd. The results suggest that phytochelatins participate in protecting the root against Cd interferences with growth, possibly by restricting Cd-induced changes in the nutrient composition of the plant.
    01/1996;
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    ABSTRACT: An investigation of fine (< 1="" mm="" in="" diameter)="" and="" small="" (1–2="" mm="" in="" diameter)="" roots="" in="" the="" organic="" soil="" layer="" was="" carried="" out="" in="" a="" norway="" spruce="" forest="" stand="" with="" different="" treatments="" of="" water="" and="" nutrients,="" including="" control="" (c);="" ammonium="" sulphate="" application="" (ns);="" nitrogen-free="" fertilization="" (v);="" irrigation="" with="" liquid="" fertilization="" (a="" complete="" nutrient="" solution)="" (if);="" ns="" followed="" by="" artificial="" drought="" (nd);="" v="" followed="" by="" artificial="" drought="" (vd).="" in="" order="" to="" evaluate="" the="" vitality="" and="" function="" of="" the="" fine="" roots,="" the="" following="" approaches="" were="" used:="" i)="" classification="" of="" fine="" roots,="" based="" on="" morphological="" characteristics;="" ii)="" nutrient="" uptake="" bioassay,="" using="">32P-phosphate and 35S-sulphate; iii) nutrient concentration in fine roots and its relation to nutrient uptake. The NS treatment showed effects on the fine and small roots, with a decrease in amount of living roots, and a decrease in the total amount of fine and small roots. The VD treatment resulted in increased amounts of living small roots, while the ND treatment showed the opposite, as compared with the V and NS treatments, respectively. The uptake of P was negatively related to the P supply, with a higher P uptake for C and NS fine roots than for IF and V fine roots. The specific root length (SRL, m g-1 DW) decreased for NS fine roots and increased for IF fine roots, indicating a further increase in uptake for NS roots and a decreased uptake for IF roots if calculated on a root length basis. So far, the NS and IF treatments maintain a considerable increase in above-ground biomass with a significantly reduced root biomass and standing crop.
    Plant and Soil 05/1995; 173(1):147-155. · 3.24 Impact Factor
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    ABSTRACT: The effect of different external cadmium (Cd) and copper (Cu) regimes on the concentration of Cd and Cu in roots and shoots of birch (Betula pendula Roth.) seedlings was investigated. The seedlings were grown for 12 days in a weak nutrient solution (containing all essential nutrient elements including 0.025 M Cu) at pH 4.2 with combinations of additional 0–2 M CdCl2 and 0–2 M CuCl2. Root and shoot concentrations of Cu were decreased by Cd in all treatments which included 0.1–2 M of additional Cu in the treatment solution. When no extra Cu was added, only the shoot concentration of Cu was decreased by Cd whereas the root concentration was not affected. The shoot concentration of Cd was decreased by 0.5 and 2 M of additional Cu in the treatment solution. The root concentration of Cd was decreased by Cu only when the concentration of additional Cu in the treatment solution was equal to or exceeded the concentration of Cd.
    Plant and Soil 03/1995; 171(1):185-187. · 3.24 Impact Factor
  • New Phytologist - NEW PHYTOL. 01/1995; 129(4):537-546.
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    ABSTRACT: We studied the effects of excess nitrogen added as nitrate (NO(3) (-)) or ammonium (NH(4) (+)), or both, on mineral nutrition and growth of beech (Fagus sylvatica L.) plants grown at pH 4.2 in Al-free nutrient solution or in solutions containing 0.1 or 1.0 mM AlCl(3). A high external concentration of NH(4) (+) increased the concentration of nitrogen in roots, stems and leaves. The root/shoot dry weight ratio was less in plants grown in the presence of NH(4) (+) than in plants grown in the presence of NO(3) (-). The concentration of phosphorus in the roots was increased and the concentration of potassium in all parts of the plant was decreased by NH(4) (+). A high external concentration of NO(3) (-) caused a decrease in phosphorus concentrations of the root, stem and leaf. Uptake of (45)Ca(2+) by roots was reduced in the presence of high concentrations of NH(4) (+) or NO(3) (-), and a combination of high concentrations of nitrogen and aluminum further reduced the uptake of (45)Ca(2+). Uptake of phosphate ((32)P) and concentrations of phosphorus in root and shoot were increased when plants were grown in the presence of 0.1 mM Al. Exposure to 1.0 mM Al, however, reduced the concentration of phosphorus in roots and shoots and the reduction was greater when plants were grown in the presence of a high external NO(3) (-) concentration. Aluminum binds to roots, and plants grown in the presence of 1.0 mM Al had a slightly higher concentration of aluminum in roots than plants grown in the presence of 0.1 mM Al, whereas the concentration of Al in the shoot was increased 2 to 3 times in plants exposed to 1.0 mm Al. Furthermore, the effects of 1.0 mM Al on uptake of other macronutrients were quite different from the effects of 0.1 mM Al. We conclude that 0.1 mM Al facilitates uptake and transport of phosphorus in beech and that between 0.1 and 1.0 mM Al there is a dramatic change in the effects of Al on uptake and transport of divalent cations and phosphorus.
    Tree Physiology 02/1994; 14(1):63-73. · 2.85 Impact Factor
  • Journal of Experimental Botany - J EXP BOT. 01/1994; 45(12):1823-1827.