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1.
Abstract

A hydroponic experiment was conducted to observe the effect of arsenic (As) on a number of physiological and mineralogical properties of rice (Oryza sativa L. cv. Akihikari) seedlings. Seedlings were treated with 0, 6.7, 13.4 and 26.8 µmol L?1 As (0, 0.5, 1.0 and 2.0 mg As L?1) for 14 days in a greenhouse. Shoot dry matter yield decreased by 23, 56 and 64%; however, the values for roots were 15, 35 and 42% for the 6.7, 13.4 and 26.8 µmol L?1 As treatments, respectively. Shoot height decreased by 11, 35 and 43%, while that of the roots decreased by 6, 11 and 33%, respectively. These results indicated that the shoot was more sensitive to As than the root in rice. Leaf number and width of leaf blade also decreased with As toxicity. Arsenic toxicity induced chlorosis symptoms in the youngest leaves of rice seedlings by decreasing chlorophyll content. Concentrations and accumulations of K, Mg, Fe, Mn, Zn and Cu decreased significantly in shoots in the 26.8 µmol L?1 As treatment. However, the concentration of P increased in shoots at 6.7 and 13.4 µmol L?1 As levels, indicating a cooperative rather than antagonistic relationship. Arsenic and Fe concentration increased in roots at higher As treatments. Arsenic translocation (%) decreased in the 13.4 and 26.8 µmol L?1 As treatments compared with the 6.7 µmol L?1 As treatment. Arsenic and Fe were mostly concentrated in the roots of rice seedlings, assuming co-existence of these two elements. Roots contained an almost 8–16-fold higher As concentration than shoots in plants in the As treatments. Considering the concentration of Mn, Zn and Cu, it was suggested that chlorosis resulted from Fe deficiency induced by As and not heavy-metal-induced Fe deficiency.  相似文献   

2.
Abstract

Phytoremediation is a good technique for removing cadmium (Cd) from farmland soils. To remove Cd from these soils effectively, it is necessary for Cd ions to be transported to the shoot organs for later harvest. However, the mechanism of Cd translocation to shoot organs via xylem vessels has not yet been elucidated. We selected oilseed rape plants (Brassica napus L.) and established a method to collect xylem exudates from these plants. After 3 days of Cd treatment (10 µmol L?1 and 30 µmol L?1) the Cd concentrations in the xylem exudates were approximately 6.5 µmol L?1 and 16 µmol L?1, respectively. The detection of Cd in the xylem exudate indicated that Cd was moving to shoot organs via xylem vessels. The effect of these Cd treatments on the amino acid, organic acid and protein composition of xylem exudates from oilseed rape plants was investigated. The level of amino acids and organic acids detected was enough to bind Cd transported via the xylem. Sodium dodecylsulfate-polyacrylamide gel electrophoresis analysis revealed that proteins with molecular weights of 36 kDa and 45 kDa clearly increased in the exudates with Cd treatment. The possibility that these compounds are binding Cd in the xylem exudates was discussed.  相似文献   

3.
Abstract

To assess soil-to-plant transfer of various elements more precisely, the concentrations of the elements extracted from soil samples using eight chemical solutions were compared with the results of a pot cultivation experiment of komatsuna (Brassica rapa L. var. perviridis) or buckwheat (Fagopyrum esculentum M.) using the soils. From agricultural fields in Aomori, Japan, 16 soil samples were collected. Elements in the samples were extracted using acids (1 mol L?1 HNO3, 0.1 mol L?1 HNO3, 0.01 mol L?1 HNO3), chelating agents (0.05 mol L?1 EDTA), neutral salt solutions (1 mol L?1 NH4OAc, 1 mol L?1 NH4NO3, 0.01 mol L?1 CaCl2) and pure water. The 28 elements in the extracted solutions and plant samples were determined. The extractability of many metals was higher in 1 mol L?1 HNO3, 0.1 mol L?1 HNO3 and the 0.05 mol L?1 EDTA solutions than in the other extractants. Higher extractability using the NH4OAc solution than the NH4NO3 solution was observed for some elements, in particular U. Extractability by pure water was not always lowest among these methods, probably because of dispersion of colloidal substances in the extracted solution. The pot cultivation experiment showed that the concentrations in soil and in the extracted fraction using 1 mol L?1 HNO3, 0.1 mol L?1 HNO3 or the EDTA solution did not correlate with the concentration in plant samples for most elements. Plant uptake of Zn, Y and La by komatsuna correlated well with their concentrations in extracts with neutral salt solutions or 0.01 mol L?1 HNO3. Concentrations of Al, Cu and Cd in buckwheat were also correlated with the concentrations in the extracts.  相似文献   

4.
Abstract

Hydroponically grown barley plants (Hordeum vulgare L. cv. Minorimugi) under iron-deficient (–Fe) and high phosphorus (P) conditions (500 µmol L?1) showed Fe chlorosis and lower growth compared with plants grown in –Fe and low P conditions (50, 5 and 0.5 µmol L?1). To understand the physiological role of P in regulating the growth of plants in –Fe medium, we carried out an Fe feeding experiment using four P levels (500, 50, 5 and 0.5 µmol L?1) and phytosiderophores (PS), mugineic acid. Our results suggest that plants grown in a high P medium had higher absorption activity of 59Fe compared with plants grown in low P media, irrespective of the presence or absence of added PS. Translocation of 59Fe from roots to shoots was not affected by the P level. The relative translocation rate of 59Fe increased with decreasing levels of P in the medium. In general, the addition of PS enhanced the absorption of 59Fe and its translocation. Taken together these results suggest that the lower relative translocation rate of Fe in high P plants may be induced by the physiological inactivation of Fe in the roots, and the higher absorption activity of Fe in high P conditions possibly results from the response of barley plants to Fe deficiency.  相似文献   

5.
《Journal of plant nutrition》2013,36(5):1065-1083
Abstract

Ten cvs. of four Brassicaceae species were tested to evaluate their copper (Cu) uptake and translocation. Germination and root length tests indicated that Brassica juncea cv. Aurea and Raphanus sativus cvs. Rimbo and Saxa were the species with the highest germinability and longest roots at Cu concentrations ranging from 25 up to 200 µM. Raphanus sativus cv. Rimbo grown in hydroponic culture at increasing Cu concentrations (from 0.12 up to 40 µM) for 10 days produced a relatively high biomass (17.2 mg plant?1) at the highest concentration and had a more efficient Cu translocation (17.8%) in comparison with cvs. Aurea and Saxa. The potential of cv. Rimbo for Cu uptake was then followed for 28 days at 5, 10, and 15 µM Cu. In comparison with the control, after 28 days of growth the 15 µM Cu‐treated plants showed a reduction in the tolerance index (?40%) and in the above‐ground dry biomass (?19%). On the contrary, an increase in the below‐ground dry weight was observed (+35%). Copper accumulated during the growth period both in the below‐ and above‐ground parts (about 14 and 4 µg plant?1 at 10 and 15 µM Cu, respectively), but the translocation decreased from 50 to 30% in the last week at all the concentrations used. In addition, cv. Rimbo grown in a multiple element [cadmium (Cd), chromium (Cr), Cu, lead (Pb), and zinc (Zn)] naturally‐contaminated site accumulated all elements in the above‐ground part in a range from 5 to 62 µg plant?1.  相似文献   

6.
Abstract

Hydroponic studies with soybean (Glycine max [L.] Merr.) have shown that µmol L?1 additions of Mg2+ were as effective in ameliorating Al rhizotoxicity as additions of Ca2+in the mmol L?1 concentration range. The objectives of this study were to assess the ameliorative effects of Mg on soybean root growth in acidic subsoils and to relate the soil solution ionic compositions to soybean root growth. Roots of soybean cultivar Plant Introduction 416937 extending from a limed surface soil compartment grew for 28 days into a subsurface compartment containing acid subsoils from the Cecil (oxidic and kaolinitic), Creedmoor (montmorillonitic) and Norfolk (kaolinitic) series. The three Mg treatments consisted of native equilibrium soil solution concentrations in each soil (50 or 100 µmol L?1) and MgCl2 additions to achieve 150 and 300 µmol L?1 Mg (Mg150 and Mg300, respectively) in the soil solutions. Root elongations into Mg-treated subsoils were compared with a CaCO3 treatment limed to achieve a soil pH value of 6. Subsoil root growth responses to the Mg treatments were less than for the lime treatments. Root length relative to the limed treatments for all subsoils (RRL) was poorly related to the activity of the soil solution Al species (Al3+ and Al-hydroxyl species) and Mg2+. However, the RRL values were more closely related to the parameters associated with soil solution Ca activity, including (Ca2+), (Al3+)/(Ca2+) and (Al3+)/([Ca2+] + [Mg2+]), suggesting that Ca could be a primary factor ameliorating Al and H+ rhizotoxicity in these subsoils. Increased tolerance to Al rhizotoxicity of soybean by micromolar Mg additions to hydroponic solutions, inducing citrate secretion from roots to externally complex toxic Al, may be less important in acid subsoils with low native Ca levels.  相似文献   

7.
Abstract

To clarify the mechanism of Magnesium (Mg) in alleviating cadmium (Cd) phytotoxicity, Japanese mustard spinach (Brassica rapa L. var. pervirdis) was grown for 10 days after treatment in hydroponics in a growth chamber under natural light. The treatments were: (1) nutrient solution alone (Control), (2) 10 mmol L?1 Mg (High-Mg), (3) 2.5 µmol L?1 Cd (Cd-toxic), (4) 2.5 µmol L?1 Cd plus 10 mmol L?1 Mg (Mg-alleviated). The Cd-toxic treatment showed substantial growth retardation and chlorosis of young leaves, such symptoms were not observed in Mg-alleviated plants. Magnesium-alleviated plants showed higher shoot growth, more than twofold, and decreased shoot Cd concentration, approximately 40%, compared with Cd-toxic plants. This increase in shoot growth and simultaneous decrease in shoot Cd concentration may explain the alleviation of Cd toxicity with Mg in Japanese mustard spinach. In Cd-toxic plants, concentrations of K in shoots and Zn in both shoots and roots increased compared with the other three treatments. Concentrations and accumulations of Fe and Mn in shoots decreased significantly in the Cd-treated (Cd-toxic and Mg-alleviated) plants compared with the control and High-Mg plants. Thus, the application of high amounts of Mg in the nutrient solution can alleviate Cd toxicity in plants.  相似文献   

8.
Abstract

Six desulfo-glucosinolates (DS-GSLs), DS-glucoraphanin, DS-4-(β-d-glucopyranosyldisulfanyl)butyl GSL, DS-glucoerucin, DS-glucobrassicin, DS-dimeric 4-mercaptobutyl GSL and DS-4-methoxyglucobrassicin, were isolated from rocket salad (Eruca sativa Mill.) By using high-pressure liquid chromatography (HPLC) and identified by their retention times on HPLC and electrospray ionization mass spectrometry (ESI-MS) techniques. Total GSL contents were 125, 11 and 22 µmol g?1 dry weight (DW) in seeds, leaves and roots, respectively. Two DS-GSLs, namely DS-glucoraphanin and DS-glucoerucin, were the major GSLs in seeds and roots, while DS-glucoraphanin, DS-glucoerucin and DS-dimeric 4-mercaptobutyl GSL were the predominant GSLs in leaves (> 1 µmol g?1 DW or > 10% of the total GSL content). In addition, the anti-oxidant activity (n = 3) of intact leaf and root powders, whole DS-GSL eluates and purified DS-4-methoxyglucobrassicin were measured using the XYZ-dish method. DS-4-methoxyglucobrassicin showed the greatest anti-oxidant activity value (3.8 unit g?1 DW), and the value for whole DS-GSL eluates (1.6) was higher than that of intact leaves (1.5) and roots (0.87).  相似文献   

9.
No‐till (NT) system with crop rotation is one of the most effective strategies to improve agricultural sustainability in tropical and subtropical regions. To control soil acidity in NT, lime is broadcast on the surface without incorporation. The increase in soil pH due to surface liming may decrease zinc (Zn) availability and its uptake by crops. A field experiment was performed in Paraná State, Brazil, on a loamy, kaolinitic, thermic Typic Hapludox to evaluate Zn bioavailability in a NT system after surface liming and re‐liming. Dolomitic lime was surface applied on the main plots in July 1993 at the rates of 0, 2, 4, and 6 Mg ha?1. In June 2000, the main plots were divided in two subplots to study of the effect of surface re‐liming at the rates of 0 and 3 Mg ha?1. The cropping sequence was soybean [Glycine max (L.) Merrill] (2001–2 and 2002–3), wheat (Triticum aestivum L.) (2003), soybean (2003–4), corn (Zea mays L.) (2004–5), and soybean (2005–6). Soil samples were collected at the following depths: 0–0.05, 0.05–0.10, and 0.10–0.20 m, 10 years after surface liming and 3 years after surface re‐liming. Soil Zn levels were extracted by four extractants: (i) 0.005 mol L?1 diethylenetriaminepentaacetic acid (DTPA) + 0.1 mol L?1 triethanolamine (TEA) + 0.01 mol L?1 calcium chloride (CaCl2) solution at pH 7.3 (DTPA–TEA), (ii) 0.1 mol L?1 hydrochloric acid (HCl) solution, (iii) Mehlich 1 solution, and (iv) Mehlich 3 solution. Zinc concentrations in leaves and grains of soybean, wheat, and corn were also determined. Soil pH (0.01 mol L?1 CaCl2 suspension) varied from 4.4 to 6.1, at the 0‐ to 0.05‐m depth, from 4.2 to 5.3 at the 0.05‐ to 0.10‐m depth, and from 4.2 to 4.8 at the 0.10‐ to 0.20‐m depth, after liming and re‐liming. Zinc concentrations evaluated by DTPA–TEA, 0.1 mol L?1 HCl, Mehlich 1, and Mehlich 3 solutions were not changed as a result of lime rate application. Re‐liming increased Zn concentrations extracted by 0.1 mol L?1 HCl at 0–0.05 m deep and by DTPA–TEA at 0.05–0.10 m deep. Surface‐applied lime promoted a decrease in Zn concentrations of the crops, mainly in grains, because of increased soil pH at the surface layers. Regardless of the liming treatments, levels of Zn were sufficient to soybean, wheat, and corn nutrition under NT.  相似文献   

10.
Abstract

Arsenic (As) is a deadly poison at high concentrations. It is mysterious in the sense that people are exposed to it most of the time through drinking groundwater, fortunately at much lower concentrations than the deadly levels, and usually without knowing it. Arsenic content in alluvial aquifers of Punjab varied from 3.5 to 688 µg L?1. Arsenic status of groundwater is classified into low (<10 µg L?1), moderate (≥10 to <25 µg L?1), high (≥25 to <50 µg L?1), and very high (>50 µg L?1). In zone I, the concentration of As in groundwater varied from 3.5 to 42 µg L?1 with a mean value of 23.4 µg L?1. On the basis of these limits, only 8% of samples were low, whereas 51 and 41% of the total samples collected from this region fall in the moderate and high As categories. The concentration of As in groundwater of zone II varied from 9.8 to 42.5 µg L?1 with a mean value of 24.1 µg L?1. Arsenic concentration in the alluvial aquifers of the central plain of zone II is 2 and 52% in the low and moderate limits. In this region, 46% of groundwater sites contain high As concentrations. Arsenic concentrations in the aridic southwestern parts are significantly different from other two provinces. The As concentration ranged from 11.4 to 688 µg L?1 with average value of 76.8 µg L?1. Eleven percent of the aquifers of the southwestern region of zone III are in the moderate category, 54% in the high, and 35% in the very high. According to safe As limits (<10 µg L?1), only 3 and 1% of the groundwater samples collected from zones I and II were fit for dinking purposes with respect to As content. In the aridic southwest, zone III, all water samples contained As concentrations greater than the safe limits and thus are not suitable for drinking purposes. The presence of elevated As concentrations in groundwater are generally due to the results of natural occurrences of As in the aquifer materials. The concentration of other competitive oxyanions in waters such as phosphate, sulfate, and borate also depressed the adsorption of As on the sorption sites of aquifer materials and thereby eventually elevate the As concentration in groundwaters. In groundwater of alluvial aquifers of Punjab, released from sulfide oxidation and oxyhydroxide of iron, elevated (>10 µg L?1) concentrations of As were widespread because of high pH (>8.0) and higher concentrations of phosphate, borate, sulfate, and hydroxyl anions. It is conclusively evident that geochemical conditions, such as pH, oxidation–reduction, associated or competing ions, and evaporative environments have significant effects on As concentration in groundwater. These conditions influence how much As is dissolved or precipitated into the water and how much is bound to the aquifer materials or the solid particles in water.  相似文献   

11.
Abstract

To evaluate the hypothesis that plant-mediated oxygen supplies decrease methane (CH4) production and total global warming potential (GWP) in a tropical peatland, the authors compared the fluxes and dissolved concentrations of greenhouse gases [GHGs; CH4, carbon dioxide (CO2) and nitrous oxide (N2O)] and dissolved oxygen (DO) at multiple peatland ecosystems in Central Kalimantan, Indonesia. Study ecosystems included tropical peat swamp forest and degraded peatland areas that were burned and/or drained during the rainy season. CH4 fluxes were significantly influenced by land use and drainage, which were highest in the flooded burnt sites (5.75 ± 6.66 mg C m?2 h?1) followed by the flooded forest sites (1.37 ± 2.03 mg C m?2 h?1), the drained burnt site (0.220 ± 0.143 mg C m?2 h?1), and the drained forest site (0.0084 ± 0.0321 mg C m?2 h?1). Dissolved CH4 concentrations were also significantly affected by land use and drainage, which were highest in the flooded burnt sites (124 ± 84 μmol L?1) followed by the drained burnt site (45.2 ± 29.8 μmol L?1), the flooded forest sites (1.15 ± 1.38 μmol L?1) and the drained forest site (0.860 ± 0.819 μmol L?1). DO concentrations were influenced by land use only, which were significantly higher in the forest sites (6.9 ± 5.6 μmol L?1) compared to the burnt sites (4.0 ± 2.9 μmol L?1). These results suggest that CH4 produced in the peat might be oxidized by plant-mediated oxygen supply in the forest sites. CO2 fluxes were significantly higher in the drained forest site (340 ± 250 mg C m?2 h?1 with a water table level of ?20 to ?60 cm) than in the drained burnt site (108 ± 115 mg C m?2 h?1 with a water table level of ?15 to +10 cm). Dissolved CO2 concentrations were 0.6–3.5 mmol L?1, also highest in the drained forest site. These results suggested enhanced CO2 emission by aerobic peat decomposition and plant respiration in the drained forest site. N2O fluxes ranged from ?2.4 to ?8.7 μg N m?2 h?1 in the flooded sites and from 3.4 to 8.1 μg N m?2 h?1 in the drained sites. The negative N2O fluxes might be caused by N2O consumption by denitrification under flooded conditions. Dissolved N2O concentrations were 0.005–0.22 μmol L?1 but occurred at < 0.01 μmol L?1 in most cases. GWP was mainly determined by CO2 flux, with the highest levels in the drained forest site. Despite having almost the same CO2 flux, GWP in the flooded burnt sites was 20% higher than that in the flooded forest sites due to the large CH4 emission (not significant). N2O fluxes made little contribution to GWP.  相似文献   

12.
《Journal of plant nutrition》2013,36(12):2537-2549
Abstract

Selenium (Se), and boron (B), and salinity contamination of agricultural drainage water is potentially hazardous for water reuse strategies in central California. This greenhouse study assessed tolerance and Se, B, and chloride (Cl?) accumulation in different varieties (Emerald City, Samurai, Greenbelt, Marathon) of broccoli (Brassica oleracea L.) irrigated with water of the following different qualities: (1) non‐saline [electrical conductivity (EC) of <1 dS m?1]; (2) Cl?/sulfate salinity of ～5 dS m?1, 250 µg Se L?1, and 5 mg B L?1; and (3) non‐saline and 250 µg Se L?1. One hundred and ten days after transplanting, plants were harvested and dry weight (DW) yields and plant accumulation of Se, B, and Cl? was evaluated in floret, leaf, and stem. Irrespective of treatments floret yields from var. Samurai were the lowest among all varieties, while floret yields from var. Marathon was the only variety to exhibit some sensitivity to treatments. For all varieties, plant Se concentrations were greatest in the floret (up to 51 mg kg?1 DW) irrespective of treatment, and B and Cl? concentrations were greatest in the leaves; 110 mg B kg?1 DW and 5.4% Cl?, respectively. At post harvest, treatment 2 (with salinity, B, and Se) increased soil salinity to almost 6 dS m?1, total Se concentrations to a high of 0.64 mg kg?1 DW soil, and water soluble B concentrations to a high of 2.3 mg B L?1; soluble Se concentrations were insignificant. The results indicate that var. Emerald City, Greenbelt, and Marathon should be considered as recipients of moderately saline effluent enriched with Se and B under field conditions.  相似文献   

13.
A nutrient solution experiment was done to evaluate effects of different concentrations of nitrogen (N), phosphorus (P) and potassium (K) on leaf mineral concentrations and some enzymes activity of melon seedlings (Cucumismelo var. inodorus subvar. Khatouni). Different levels of these nutrients including 0, 53, 105, 158 and 210?mg L?1 N; 0, 8, 16, 23 and 31?mg L?1 P; 0, 59, 118, 176 and 235?mg L?1 K, all corresponding to 0, 25, 50, 75 and 100% of their concentrations in Hoagland nutrient solution, were applied to plants. The results showed that the highest leaf nitrate reductase (NR) activity was observed at highest N and P levels, whereas the three highest K levels showed the highest NR activity. The highest leaf peroxidase activity was observed at 8?mg L?1 P, 59?mg L?1 K and 158?mg L?1 N. The leaf catalase activity was highest at zero concentration of P, 158?mg L?1 N and 176?mg L?1 K; however, catalase activity was decreased by increasing P levels. Leaf protein content showed an increasing trend with increasing N, P and K levels of nutrient solution, while there was no significant difference between 158 and 210?mg L?1 N. The highest leaf concentrations of N, P, K and Mg were observed at highest nitrogen, potassium and phosphorus levels of nutrient solution, whereas the highest leaf concentration of Ca were obtained at 53 or 105?mg L?1 N, 176?mg L?1 K and 23–31?mg L?1 P. The highest iron concentration of leaves was obtained from 23 to 31?mg L?1 P, 176?mg L?1 K and 210?mg L?1 N.  相似文献   

14.
Abstract

We have identified Crassocephalum crepidioides (Benth.) S. Moore (Compositae) as a cadmium (Cd)-accumulator plant in a heavy-metal polluted environment. In soil polluted with Cd, 5.7–17.5 mg kg?1 Cd, concentrations in the above-ground plant tissues were measured as 14.6–78.6 mg kg?1 with transfer factors in the above-ground plant tissues (concentration in above-ground tissues/soil concentration) of 1.5–6.0. No other toxic heavy metals or plant micronutrients were found to have accumulated into the above-ground plant tissues. In a hydroponic culture with 1 µmol L?1 Cd added to Hoagland's nutrient solution, Cd concentration in the above-ground plant tissues was 121.0 mg kg?1, with a transfer factor of more than 1000. In a pot culture carried out for 9 weeks in a greenhouse, the highest Cd concentration in the above-ground plant tissues, 121.2 mg kg?1, was found in a treatment with 5 mg kg?1 Cd, whereas the highest Cd content in an above-ground plant tissue, 106.1 µg, was found in a treatment with 2 mg kg?1 Cd. These results clearly showed that C. crepidioides is a Cd accumulator. In all samples, the Cd concentration in the above-ground plant tissues was higher than that in the roots. The results obtained in the present study show that this plant has a strong potential for use in phytoremediation in farm fields contaminated with Cd.  相似文献   

15.
《Journal of plant nutrition》2013,36(12):2745-2761
ABSTRACT

Effect of cadmium (Cd) on biomass accumulation and physiological activity and alleviation of Cd-toxicity by application of zinc (Zn) and ascorbic acid in barley was studied, using semisolid medium culture including 15 treatments [four Cd concentration treatments: 0.1, 1, 5, 50?µmol?L?1, four treatments with addition of 300?µmol?L?1 Zn or 250?mg?L?1 ascorbic acid (ASA) based on these four Cd concentrations, respectively, and three controls: basic nutrient medium, and with Zn or ASA, respectively]. Cadmium addition to semisolid medium, at a concentration of 1, 5, and 50?µmol?L?1, inhibited biomass accumulation and increased malondialdehyde (MDA) content of barley plants, while the addition of 0.1?µmol?L?1 Cd increased slightly dry mass. There was a tendency to a decrease in Zn, copper (Cu) concentrations both in shoots and roots and iron (Fe) in shoots of barley plants exposed to 1 to 50?µmol?L?1 Cd. In addition, there were indications of a stress repose characterized by increased superoxide dismutase (SOD) and peroxidase (POD) activities relative to plants not subjected to Cd. The physiological changes caused by Cd toxicity could be alleviated to different extent by application of 300?µmol?L?1 Zn or 250?mg?L?1 ASA in Cd stressed plants. The most pronounced effects of adding Zn or ASA in Cd stressed medium were expressed in the decreased MDA and increased biomass accumulation, e.g., MDA contents were reduced (p≤0.01) by 4.8%–17.8% in shoots and 0.5%–19.7% in roots by adding 300?µmol?L?1 Zn, in 50?µmol?L?1 Cd stressed plants, and by 1.3%–7.4% in shoots and 2.6%–4.5% in roots by application of 250?µmol?L?1 ASA, respectively. However, ASA addition may enhance Cd translation from root to shoot, accordingly, ASA would be unsuitable for the edible crops grown in Cd contaminated soils to alleviate phytotoxicity of Cd.  相似文献   

16.
Abstract

A study was undertaken to determine the effects of different concentrations of arsenic (As) in irrigation water on Boro (dry‐season) rice (Oryza sativa) and their residual effects on the following Aman (wet‐season) rice. There were six treatments, with 0, 0.1, 0.25, 0.5, 1, and 2 mg As L?1 applied as disodium hydrogen arsenate. All the growth and yield parameters of Boro rice responded positively at lower concentrations of up to 0.25 mg As L?1 in irrigation water but decreased sharply at concentrations more than 0.5 mg As L?1. Arsenic concentrations in grain and straw of Boro rice increased significantly with increasing concentration of As in irrigation water. The grain As concentration was in the range of 0.25 to 0.97 µg g?1 and its concentration in rice straw varied from 2.4 to 9.6 µg g?1 over the treatments. Residual As from previous Boro rice showed a very similar pattern in the following Aman rice, although As concentration in Aman rice grain and straw over the treatments was almost half of the As levels in Boro rice grain. Arsenic concentrations in both grain and straw of Boro and Aman rice were found to correlate with iron and be antagonistic with phosphorus.  相似文献   

17.
Abstract

Growth response of a halophyte species, Suaeda salsa (L.) Pall, to graded NaCl concentrations was examined under water culture conditions. Growth increased with increasing NaCl concentration from 2 to 200 mol m?3, but decreased at NaCl concentrations above 200 mol m?3. Maximum growth was attained at 50 to 200 mol m?3. The role of Na and Cl in the growth stimulation by NaCl was examined by growing S. salsa in nutrient solutions with or without Na and Cl separately at 5 and 50 mol m?3. The growth stimulation induced by Cl was greater than that induced by Na, and Na did not significantly induce growth stimulation. The effect of Na or Cl on O2 evolution from leaves was examined under 5 and 50 mol m?3 concentrations using an oxygen electrode. Oxygen evolution from leaves in –Cl treatments was smaller than that in +Cl treatments both at 5 and 50 mol m?3. The O2 evolution in Na treatments with Cl was similar to that at NaCl. These results indicated that the mechanism of growth stimulation induced by Cl was mainly an increased photosystem II of photosynthesis in leaves. The contribution of Na on the growth stimulation of S. salsa by NaCl was smaller than Cl.  相似文献   

18.
Abstract

Growth, mineral nutrition, leaf chlorophyll and water relationships were studied in cherry plants (cv. ‘Bigarreau Burlat’[BB] and ‘Tragana Edessis’[TE]) grafted on ‘Mazzard’ rootstock and grown in modified Hoagland solutions containing 0, 25 or 50 mmol L?1 NaCl, over a period of 55 days. Elongation of the main shoot of the plants treated with 25 or 50 mmol L?1 NaCl was significantly reduced by approximately 29–36%, irrespective of the cultivar. However, both NaCl treatments caused a greater reduction in the dry weight of leaves and scion's stems in BB than in TE plants. Therefore, BB was more sensitive to salinity stress than TE. The reduction of leaf chlorophyll concentration was significant only when BB and TE plants were grown under 50 mmol L?1 NaCl. Osmotic adjustment permitted the maintenance of leaf turgor in TE plants and induced an increase in leaf turgor of BB plants treated with 25 or 50 mmol L?1 NaCl compared with 0 mmol L?1 NaCl. Concerning the nutrient composition of various plant parts, Na concentrations in all plant parts of both cultivars were generally much lower than those of Cl. For both cultivars, leaf Cl concentrations were much higher than the concentrations in stems and roots, especially in the treatments containing NaCl. Finally, the distribution of Na within BB and TE plants treated with NaCl was relatively uniform.  相似文献   

19.
Three hydroponic experiments were set up to study the rhizofiltration of cadmium (Cd) or nickel (Ni) from artificially contaminated nutrient solution with sunflower, squash, or Indian mustard. After 48 h of exposure with 2 mg L?1 Cd‐contaminated water, 460, 415, or 1092 µg Cd g?1 (dry weight) was detected in roots of 33‐day‐old sunflower and squash or in 50‐day‐old Indian mustard, respectively. As calculated, 1 g of root dry matter of the tested crop species removed 5.7–12.4% of total Cd content present in the nutrient solution. It was supposed that pseudomonads (soil rhizoplane bacteria) and the plant growth hormone ethylene can enhance the specific surface of roots and hence roots' metal adsorption capacity. As a trend, pretreatment of Indian mustard with Pseudomonas fluorescens bacteria enhanced slightly the Cd (from 1793 to 2346 µg g?1) or Ni (from 1088 to 1192 µg g?1) concentration of roots. Cadmium concentration in roots was also enhanced from 2694 to 3273 µg g?1 when the roots of Indian mustard were pretreated with Cd‐tolerant rather than Cd‐sensitive Pseudomonas cepacia. In spite of the occurrence of new root hairs, the pretreatment of roots with ethylene proved to be ineffective in enhancement of the Cd rhizofiltration capacity of Indian mustard.  相似文献   

20.
A greenhouse experiment was carried out to evaluate chromium (Cr) toxicity in urograndis (Eucalyptus urophylla S. T. Blake x grandis W. Hill ex. Maiden). Chromium nitrate was amended to Clark's nutrient solution (0.00, 0.04, 0.08, 0.16, 0.32 and 0.64 mmol L?1 Cr), which was used to breed one urograndis cutting per pot (four replications). Regression analysis revealed that Cr rates of 0.08 mmol L?1 or higher significantly decreased (P < 0.01) dry matter yield of shoot and root. Chromium accumulation order in plant was: root > stem > leaves. Critical Cr toxicity level in leaves was 0.74 mg kg?1. Uptake and translocation of nutrients were affected differently by Cr. Mostly have their uptake reduced due to root damage. Magnesium, iron and manganese translocation increases, supposedly to maintain normal photosynthetic activity. Wilting is the main visual symptom of Cr toxicity. Urograndis may be suitable for contaminated sites phytostabilization and receive industrial waste fertilization.  相似文献   

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