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1.
The objective of this study was to determine relations between Al effects and mineral concentrations in citrus seedlings. Six‐month‐old seedlings of five citrus rootstocks were grown for 60 days in supernatant nutrient solutions of Al, P, and other nutrients. The solutions contained seven levels of Al ranging from 4 to 1655 μM. Al and similar P concentrations of 28 μM P. Aluminum concentrations in roots and shoots increased with increasing Al concentration in the nutrient solution. Aluminum concentrations in roots of Al‐tolerant rootstocks were higher than those of Al‐sensitive rootstocks. When Al concentrations in nutrient solution increased from 4 to 178 μM, the K, Mg, and P concentrations in roots and the K and P levels in shoots increased. Conversely, Ca, Zn, Cu, Mn, and Fe in the roots and Ca, Mg, Cu, and Fe in the shoots decreased. The more tolerant rootstocks contained higher Fe concentrations in their roots than did the less tolerant ones when Al concentrations in solution were lower than 308 μM. Concentrations of other elements (Ca, K, P, Mg, Zn, and Mn) in roots or shoots exhibited no apparent relationship to the Al tolerance for root or shoot growth of the rootstocks. Calcium, K, Zn, Mn, and Fe concentrations in roots and Mg and K concentrations in shoots of all five rootstocks seedlings had significant negative correlations with Al concentrations in corresponding roots or shoots.  相似文献   

2.
Tolerance to aluminium and manganese toxicity at the seedling stage for 72 maize accessions was examined in solution culture. 0.22 mM Al and 2.0 mM Mn gave better genotypic separation for aluminium and manganese tolerance assessed on the basis respectively of relative root length, and visual symptoms of leaf chlorosis and necrosis. There was considerable variability among accessions for tolerance to aluminium and to manganese. Three accessions, Bozm 1335, Bozm 1337, and Bozm 1536 showed tolerance to Al, while 4, Chzm 01009, Champ, Bozm 0715, LG 20.80 exhibited tolerance to Mn. Accession, Zea 769 was tolerant to both metals. A significant Al x Mn interaction was found when five accessions were grown in a mixture of 0.22 mM aluminium and 2.0 mM manganese. Root length inhibition in Al alone was slightly ameliorated when the accessions were grown in the Al + Mn solution. Tolerance to aluminium and manganese does not necessarily coincide, different mechanisms being involved in tolerance to the two metals.  相似文献   

3.
The effects of low aluminum (Al) activity in nutrient solution on the concentrations of organic acids in two cultivars of maize (Zea mays L.), HS7777 Al‐sensitive and C525‐M Al‐tolerant, were studied. Aluminum stress increased total organic acid concentration in the roots and in the shoots for both cultivars. The relative increase of t‐aconitic, citric, formic, malic, and quinic acids was higher in the roots than in the shoots for both cultivars. The concentrations of c‐aconitic, isocitric, malonic, oxalic, and succinic organic acids were reduced by Al stress, principally for C525‐M. There were no consistent differences in organic acid concentrations between the cultivars to discriminate Al tolerance. The Al tolerance for C525‐M may be justified by lower Al concentrations in the root tips where cellular division takes place and/or by higher excretion of organic acids from roots to the rhizosphere for detoxification of Al by chelation.  相似文献   

4.
The effect of increasing aluminum (Al) concentrations on root nutrient contents along with the concurrent translocation to the shoot of C4 plants prompted this study. Two‐week‐old maize (Zea mays cv XL‐72.3) plants were therefore submitted for 20 days to Al concentrations ranging from 0 to 3.00 mM in a medium with low ionic strength were used as a test system. Aluminum concentrations in root tissues showed a 3‐fold increase between 0 and 3.00 mM Al treatment, and was not detected in the shoot. Root plasma membrane‐H+ ATPase activity decreased after the 0.33 mg L‐1 Al treatment, while membrane permeability increased up to 1.00 mM Al treatment. Root and shoot biomass decreased after the 0.33 mM Al treatment. All elements in the roots, except potassium (K), manganese (Mn), and zinc (Zn) were highest for plants treated with 0.33 mM Al. Potassium increased continuously between 0 and 3.00 mM Al treatments, and iron (Fe) decreased above 0.33 mM. Only a slight decrease in nitrogen (N) was observed. All the measured nutrients in shoots, except N, Mn, and Fe decreased above 0.33 mM, but calcium (Ca) and magnesium (Mg) had little variation as Al varied. Data indicated that maximum net uptake for mineral nutrients, except Mn, occurred up to 0.33 mM Al. Translocation of phosphorus (P), K, Mn, and Zn decreased above 0.33 mM Al, N, and Ca decreased when any Al was added, and no clear trend was observed for Mg and Fe. Between the 0 and the 3.00 mM Al treatments, electrolytic conductance did not increased significantly indicating that the observed inhibitions of translocation from roots to shoots were not directly related to increasing membrane degradation.  相似文献   

5.
Abstract

Manganese (Mn) tolerance response in two aluminum (Al)‐tolerant triticale (× Triticosecale Wittmack) varieties was characterized by measurements of growth and dry matter production of seedlings in nutrient solution culture containing 100 mg L‐1 Mn. Root weight index (RWI) and total weight index (TWI) based on relative plant growth were two indicators of differentiating genotypic Mn tolerance; these two indices were used to make a comparative assessment of the degree of Mn tolerance in a group of eight Australian and South African genotypes which differ in apparent Al tolerance. The G4–95A was more Mn‐tolerant than its Al‐tolerant counterpart Tahara. A wide range of Mn tolerance was found in the eight genotypes, but few were tolerant of both Al and Mn stresses; measurements of RWI at 100 mg L‐1 Mn stress differentiated them into three response types (i.e., Mn‐tolerant, moderately Mn‐tolerant/Mn‐sensitive, and Mn‐sensitive) at the two critical values of 0.30 and 0.60. Covariation analysis indicated no association between Mn tolerance and Al tolerance; selective breeding for acidic stress tolerance should focus on both stress tolerances.  相似文献   

6.
Tolerance to zinc (Zn) deficiency was examined for three wheat (Triticum aestivum L.) and three barley (Hordeum vulgare L.) varieties grown in chelator‐buffered nutrient solution. Four indices were chosen to characterize tolerance to Zn deficiency: (1) relative shoot weight at low compared to high Zn supply (“Zn efficiency index”), (2) relative shoot to root ratio at low compared to high Zn supply, (3) total shoot uptake of Zn under deficient conditions, and (4) shoot dry weight under deficient conditions. Barley and wheat exhibited different tolerance to Zn deficiency, with barley being consistently more tolerant than wheat as assessed by all four indices. The tolerance to Zn deficiency in the barley varieties was in the order Thule=Tyra>Kinnan, and that of wheat in the order Bastian=Avle>Vinjett. The less tolerant varieties of both species accumulated more P in the shoots than the more tolerant varieties. For all varieties, the concentrations of Mn, Fe, Cu, and P in shoot tissue were negatively correlated with Zn supply. This antagonism was more pronounced for Mn and P than for Cu and Fe. Accumulation of Cu in barley roots was extremely high under Zn‐deficient conditions, an effect not so clearly indicated in wheat.  相似文献   

7.
The effect of salinity on growth response, nitrogen (N) fixation and tissue mineral content was investigated for four legumes: faba bean (Vicia faba L), pea (Pisum sativum L), soybean (Glycine max L), and common bean (Phaseolus vulgaris L). Plants were grown in a vermiculite culture system supplied with a N‐free nutrient solution with the addition of 0, 50, and 100 mM NaCl. Plants were harvested at the beginning of the flowering period and the dry weights of shoots and roots and acetylene reduction activity (ARA) were evaluated at the same time plant tissues were analysed for N, potassium (K), calcium (Ca), magnesium (Mg), and sodium (Na) contents.

The depressive effect of saline stress on ARA of nodules was directely related to the salt induced decline in dry weight and N content in shoots. Growth inhibition by NaCl treatments was greater for the pea than for other legumes, whereas the soybean was the most salt‐tolerant Saline stress also affected the N content in shoots and roots. In general the N content accumulated in the shoot and Na in the roots of the four legumes tested, while K accumulated both organs. The acquisition of other macronutrients differed according to the legume species. The legumes most sensitive were P. sativum and V. faba which accumulated Ca in shoot and Mg both in the shoot and the roots. On the contrary, in G. max and P. vulgaris, the two most salt tolerant legumes, accumulated Mg in the roots and Ca in both vegetative organs. Our results suggest a relationship between the salt‐tolerant range in legumes and the macronutrient accumulation in vegetative organs.  相似文献   

8.
A rapid and simple nutrient addition technique was used for evaluating Al tolerance of six local upland rice (Oryza sativa L.) cultivars (BG35, BR21, DA25, DA26, DA14, and DA22) from Bangladesh and three IRRI rice, IR46, IR97, and IR45, cultivars from the Philippines. The plants were grown for 21 days with Al (0 μM, 140 μM, 280 μM or 560 μM) at pH 4.1. The roots were more affected by Al than the shoots. In rating cultivars for Al sensitivity, relative shoot weight (RSW) was found to be the best parameter due to the severe damage of the roots, irrespective of Al sensitivity. The cultivars were rated as Al tolerant (BG35, BR21, DA25, and DA26), mid‐tolerant (DA14, DA22, and IR46) and sensitive (IR97 and IR45) . More Al was retained in the roots of tolerant cultivars than in the mid‐tolerant or sensitive cultivars. In shoots, the Al concentration of tolerant cultivars was less than in the mid‐tolerant or in the sensitive cultivars and the inhibition of growth was proportional to Al concentration irrespective of Al tolerance. Therefore, the variation among cultivars in Al sensitivity could be related to the capacity of roots to retain Al from transport to the shoots.  相似文献   

9.
Reports on varietal diversity of upland rice in relation to relatively low aluminium (Al) levels are limited. Therefore, effects were examined of 35, 70, and 140 μM Al on plant growth and uptake of macro‐ and micro‐nutrients (K, P, Ca, Mg, Fe, Zn, Cu, and Mn) and their distribution in three upland rice (Oryza saliva L.) cultivars (BG35, DA14, and IR45) with different Al sensitivity. After an initial growth period of 5 days without Al, the plants were grown for 21 days in nutrient solutions containing Al at pH 4.1. Cultivar BG35 showed the highest and IR45 the lowest tolerance to Al when fresh weights of shoots or roots were considered. Except for IR45 at 140 μM Al, total dry weight was unaffected by Al, and the cultivars could not be clearly distinguished with respect to Al tolerance. Net Al uptake rate was higher in Al tolerant BG35 than in DA14 or IR45. Conversely, in IR45 the absorbed Al was rapidly transported to the shoots and accumulated there. In BG35, net P and Ca uptake rates in Al‐treated plants were high enough to maintain the P and Ca status of the shoots at all Al levels. Irrespective of Al sensitivity, there was a general depression of internal Mg concentration in Al‐reated plants. The Fe, Zn, Cu, and Mn concentrations of the plants were not negatively affected by Al in any of the cultivars.  相似文献   

10.
The effects of aluminum (Al) on nitrate reductase activity, plastid pigment content, and mineral element composition in wheat, rye, and triticale seedlings were studied. Different responses of the plant species to Al content in the growth solution were observed. Under conditions of different Al concentrations (from 1 to 10 ppm), nitrate reductase (NR) activity increased in wheat and triticale, while in rye an interference with nitrate reductase by Al was observed. A definite tendency in plastid pigment content changes independent on Al levels was not found. The chlorophyll “a”;, chlorophyll “b”;, and carotenoid contents were influenced in a different way in wheat, rye, and triticale seedlings. A positive effect of 1, 5, and 10 ppm Al on the nitrogen (N) content in the shoots of wheat and rye was observed. The N content in the shoots of triticale was not affected by the presence of Al. The presence of Al in the nutrient solution led to a tendency toward reduction of potassium (K), calcium (Ca), and magnesium (Mg) contents in the shoots of rye seedlings, a reduction of K in the shoots and manganese (Mn) content in roots of wheat, and a reduction of K in both shoots and roots and an accumulation of Mn in triticale roots. In general, our investigation on the effect of Al in the early stages of wheat, rye, and triticale development showed that a large number of biochemical and physiological parameters are required to characterize the plant responses to Al stress.  相似文献   

11.
The effects of silicon (Si) on the toxicity of aluminum (Al) to mungbean (Phaseolus aureus Roxb.) seedlings were studied in a growth chamber. Mungbean seedlings were grown in a nutrient solution with combinations of three concentrations of Si (0,1, and 10 mM) and three concentrations of Al (0, 2, and 5 mM) in randomized completely block design experiments for 16 days. Silicon at 1 mM in the solution decreased root length, fresh and dry weights, and chlorophyll content, and showed no significant effect on epicotyl length and seedling height, and protein contents of shoots or roots in mungbean seedling under no Al stress. But, Si at 10 mM showed marked toxic effects on mungbean seedling growth and increased protein contents of the shoots or roots. In contrast, under 2 mM Al stress, Si addition at 1 mM had significant increasing effect on root length, fresh and dry weights, and chlorophyll content. It also had decreasing effect on protein contents of the shoots or roots, and had no effect on epicotyl length and seedling height. Silicon addition at 10 mM showed no effect on morphological and physiological measurements of mungbean seedling. However, Si at 1 mM added to solution only increased seedling height, epicotyl length, fresh weight, and chlorophyll content, but decreased dry weight and protein content of the roots under 5 mM Al stress, significantly. Silicon addition at 10 mM showed similar toxic effects on mungbean seedling growth under 5 mM Al stress to that under no Al stress.  相似文献   

12.
《Journal of plant nutrition》2013,36(10):2143-2149
ABSTRACT

Two cultivars of pea with different sensitivity to bicarbonate (Merveille de Kelvedon, tolerant and PS210713, sensitive) were cultivated during one month on a nutrient solution containing or not bicarbonate (10 mM). The study indicated that bicarbonate increased the root to shoot ratio much more in the sensitive than in the tolerant one. Bicarbonate reduced iron translocation towards shoots of the two cultivars. This effect was more marked in the sensitive one. The study also showed that bicarbonate provoked a considerable accumulation of iron in roots of the two cultivars. This accumulation was due to iron accumulated in the extraplasm of roots.  相似文献   

13.
The effects of Al on nitrate uptake and on the activity of the nitrate reductase (NR) in two hybrid cultivars of sorghum (Sorghum bicolor (L.) Moench) differing in Al tolerance were studied. The nitrate uptake by intact root system was strongly reduced by Al in both cultivars, but mainly in the Al‐sensitive cultivar. The kinetic constants also changed in the presence of Al: Vmax decreased 98% and 71% and Km increased 267% and 42% in the Al‐sensitive and Al‐tolerant cultivar, respectively. Aluminum reduced the in vitro NR activity on the roots and shoots of both cultivars, especially of the Al‐sensitive cultivar. Aluminum added to the nutrient solution or to the reaction mixture, however, inhibited differentially the NR of the roots and shoots, indicating marked differences between the enzymes from these two tissues. Aluminum reduced the Vmax but did not affect the Km of nitrate activation of the shoot NR. Therefore, Al inhibition of the NR was non‐competitive and could not be reversed by increasing nitrate concentration. Aluminum not only reduced the nitrate uptake but also had a direct effect on the NR and consequently on nitrate reduction. A correlation between NR tolerance to Al and plant tolerance to Al was observed.  相似文献   

14.
The effect of aluminum (Al) ions on the germination of wheat (Triticum aestivum L.) seeds has been investigated using two varieties, one sensitive to Al (Robin) and the other relatively Al‐tolerant (Carazinho). High concentrations of Al (i.e. greater than 1 mM) were required to inhibit the growth of the emerging roots and shoots of germinating seeds of both varieties. Moreover, Al at concentrations up to 10 mM did not affect the mobilization of carbohydrate reserves in the germinating seeds. It was concluded that germinating seeds of both wheat varieties were much less sensitive to the effects of Al than were established seedlings.  相似文献   

15.
Aluminum (Al) and chromium (Cr) stresses often occur simultaneously in agricultural soils, and pose a great damage to crop growth, yield formation and product safety. In the current study, the influence of combined Al and Cr stresses on plant biomass, metal and nutrient contents was determined in comparison with that of Al or Cr stress alone. A hydroponic experiment was conducted to investigate the effect of pH, Al and Cr in the medium solution on the uptake of mineral elements as well as Al and Cr in the two barley genotypes differing in Al tolerance. Aluminum sensitive genotype Shang 70-119 had significantly higher Cr and Al contents in plants than Al-tolerant genotype Gebeina. Barley roots had much higher Al and Cr contents than above-ground plant parts. Chromium contents were much higher in the solution with pH 4.0 than in that with pH 6.5. Aluminum stress reduced phosphorus (P), calcium (Ca), magnesium (Mg), sulfur (S), copper (Cu), manganese (Mn), zinc (Zn) and boron (B) contents in roots and restrained potassium (K) and iron (Fe) from being translocated into shoots and leaves. Chromium stress resulted in reduced P, K, Mg, S, Fe, Zn and Mn contents in roots at pH 6.5 and P, K, Ca, Mg, S, Zn and Mn contents at pH 4.0. Translocation of all nutrients from roots to upper parts of plants was inhibited except Ca in pH 6.5 with Cr addition. Lower contents of all nutrients were observed at pH 4.0 as compared to pH 6.5. Combined stress of Cr and Al, on the whole, caused further reduction in mineral content in all plant parts of the two barley genotypes as compared to Al or Cr stress alone. Moreover, the reduction was more pronounced in Al sensitive genotype Shang 70-119.  相似文献   

16.
An estimated 40% of arable soils worldwide contain phytotoxic levels of aluminum (Al). Recent evidence indicates that Al‐stress‐induced low molecular weight proteins may bind Al in Al‐tolerant plants. The objective of this study was to investigate protein patterns in young roots of two Al‐sensitive and two Al‐tolerant alfalfa (Medicago sativa L.) clones grown at 0 and 111 μmol Al in pH 4.5 nutrient solution. Based on SDS‐PAGE of supernatant, Al stress resulted in an increase in detectable root proteins in all clones and results are consistent with results reported for other plant species. A proliferation of new low‐molecular‐weight proteins in the tolerant clones could be related to Al tolerance. One protein (18.7 kD) was produced in both tolerant clones yet not detected in the sensitive clones. Protein levels were more often reduced than enhanced under Al stress and reduction was more prevalent in sensitive than in tolerant clones. Aluminum stress may initiate the production of some of the same proteins in alfalfa and wheat (Triticum aestivum L. Thell.). General stress proteins could be produced in reaction to a variety of chemical, environmental, and pathological stresses.  相似文献   

17.
An estimated 30% of the world's arable soils are acidic and aluminum (Al) toxicity is often the primary growth‐limiting factor. Excess Al is especially undesirable in sub‐soils because it reduces rooting depth and branching and predisposes plants to drought injury. Liming the plow layer does not generally neutralize subsoil phytotoxicity and Al‐tolerant cultivars offer an alternative or supplemental solution to the problem. Genetic diversity for acid soil tolerance in alfalfa (Medicago sativa L.) is limited and a better understanding of the basic tolerance mechanisms would facilitate the design of more efficacious breeding procedures. Evidence is accumulating that organic acids and proteins elicited by Al stress may complex and detoxify Al either within, or external to, the root. Because Al is a paramagnetic element that can reduce T2 relaxation times (inter‐proton interactions) markedly, the mechanism of Al tolerance in alfalfa was investigated through T2‐based Magnetic Resonance Imaging (MRI) of young lateral root sections of an Al‐sensitive and an Al‐tolerant alfalfa clone grown in nutrient solution (0 or 111 μmol Al; pH 4.5). Root sections that developed under phytotoxic levels of Al accumulated considerable Al in the epidermis and internal root tissue. Aluminum may have been complexed by low molecular weight proteins and organic acids in the tolerant clone whereas the sensitive clone appeared to have abundant free Al; however, variation among replications indicates that free Al may still have been present in tolerant roots and that other tolerance mechanisms may also be important. Root buds accumulated little Al compared to the remainder of the root, indicating that the pronounced effects of Al on lateral root development are indirect. Magnetic Resonance Imaging images evaluated in this study provided clues to the basic mechanisms of Al tolerance in alfalfa and, with further refinement, could be used as one criterion for selecting Al‐tolerant plants.  相似文献   

18.
Abstract

Barley, Hordeum vulgare L., is extremely sensitive to excess soluble or exchangeable aluminum (Al) in acid soils having pH values below about 5.5. Aluminum tolerant cultivars are needed for use in rotations with potatoes which require a soil pH below 5.5 for control of scab disease. They are also potentially useful in the currently popular “low input, sustainable agriculture (LISA)”; in which liming even the plow layer of soil is not always possible or cost effective, or in situations where surface soils are limed but subsoils are acidic and Al toxic to roots. Ten barley cultivars were screened for Al tolerance by growing them for 25 days in greenhouse pots of acid, Al‐toxic Tatum subsoil (clayey, mixed, thermic, typic Hapludult) treated with either 750 or 4000 μg?g‐1 CaCO3 to produce final soil pH values of 4.4 and 5.7, respectively. Based on relative shoot dry weight (weight at pH 4.4/weight at pH 5.7 X 100), Tennessee Winter 52, Volla (England), Dayton and Herta (Denmark) were significantly more tolerant to the acid soil than Herta (Hungary), Kearney, Nebar, Dicktoo, Kenbar and Dundy cultivars. Relative shoot dry weights averaged 28.6% for tolerant and 14.1% for sensitive cultivar groups. Comparable relative root dry weights were 41.7% and 13.7% for tolerant and sensitive cultivars, respectively. At pH 4.4, Al concentrations were nearly three times as high in shoots of sensitive cultivars as in those of the tolerant group (646 vs. 175 μg?g‐1), but these differences were reduced or absent at pH 5.7. At pH 4.4, acid soil sensitive cultivars also accumulated phosphorus concentrations that were twice as high as those in tolerant cultivars (1.2% vs. 0.64%). At pH 5.7, these P differences were equalized at about 0.7% for both tolerant and sensitive groups. At pH 4.4, shoots of the Al‐sensitive cultivar Nebar contained 1067 μg?g‐1 Al and 1.5% P. Concentrations of Al and P in the shoots of acid soil sensitive cultivars grown at pH 4.4 exceeded levels reported to produce toxicity in barley. The observed accumulation of such concentrations of Al and P in the shoots of plants grown under Al stress is unusual and deserves further study.  相似文献   

19.
Variability in millet stands in West Africa is clearly visible as early as three weeks after planting. The objectives of this study were to determine the influence of pH and chemical toxicities on millet germination and seedling growth and to compare varietal tolerance of toxic conditions. A nutrient solution study was carried out with a series of Hoagland‐based nutrient solutions. Germination percentage was calculated, and root and shoot lengths were measured for one week. Critical values were determined for toxic elements. The only treatment which reduced germination percentage significantly was copper (Cu) concentrations >0.05M. Solution pH values between 5 and 7 resulted in the best root growth, though shoot growth was unaffected by pH. The roots were more sensitive than the shoots to several [aluminum (Al), boron (B), zinc (Zn)] of the elemental toxicities studied. Soil Al and manganese (Mn) levels may be high enough to have toxic effects on millet roots. However, natural soil iron (Fe), Cu, and Zn levels were much lower than the critical levels determined in the nutrient solution study. The improved varieties were more tolerant of Fe and Zn toxicity than the LOCAL variety, but the LOCAL variety was more tolerant of high B concentrations.  相似文献   

20.
Abstract

This paper reports the reaction of 24 Australian wheats and 16 overseas cultivars to high aluminium (Al) in solution culture. These results are compared with those from a rapid haematoxylin stain test. The relationship between the haematoxylin stain test results and performance in the field was also determined.

The dry matter yields in solution culture confirmed tolerances previously reported for the non‐Australian cultivars, with only two exceptions. The Australian varieties vary in tolerance but none were as tolerant as those from Brazil. The tolerances of the Australian varieties were not related to the breeding origins of the varieties. Exposure to Al in solution differentially reduced the concentration of calcium (Ca), magnesium (Mg), and phosphorus (P) in both shoots and roots. The more Al‐tolerant varieties were less affected.

The results obtained in solution culture and in the haematoxylin stain test generally agreed, but more differences between varieties were noted in solution culture results. The haematoxylin stain test was then used to classify cultivars and advanced lines in the breeding programme, and the results were compared with yield performance on acid (8 sites) and non‐acid soils (20 sites). The lines in haematoxylin class 4 had a 20% yield advantage over the acid sites.

We concluded that tolerance was useful in the field, that the haematoxylin stain test is useful as a rapid preliminary assessment of Al tolerance, and that the prospect of breeding cultivars with improved tolerance was rewarding.  相似文献   

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