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1.
We investigated the effect of ectomycorrhizal colonization, charcoal and CO2 levels on the germination of seeds of Larix kaempferi and Pinus densiflora, and also their subsequent physiological activity and growth. The seeds were sown in brown forest soil or brown forest soil mixed with charcoal, at ambient CO2 (360 μmol mol−1) or elevated CO2 (720 μmol mol−1), with or without ectomycorrhiza. The proportions of both conifer seeds that germinated in forest soil mixed with charcoal were significantly greater than for seeds sown in forest soil grown at each CO2 level (P < 0.05; t-test). However, the ectomycorrhizal colonization rate of each species grown in brown forest soil mixed with charcoal was significantly lower than in forest soil at each CO2 treatment [CO2] (P < 0.01; t-test). The phosphorus concentrations in needles of each seedling colonized with ectomycorrhiza and grown in forest soil were greater than in nonectomycorrhizal seedlings at each CO2 level, especially for L. kaempferi seedlings (P < 0.05; t-test), but the concentrations in seedlings grown in brown forest soil mixed with charcoal were not increased at any CO2 level. Moreover, the maximum net photosynthetic rate of each seedling for light and CO2 saturation (P max) increased when the seedlings were grown with ectomycorrhiza at 720 μmol mol−1 [CO2]. Ectomycorrhizal colonization led to an increase in the stem diameter of each species grown in each soil treatment at each CO2 level. However, charcoal slowed the initial growth of both species of seedling, constraining ectomycorrhizal development. These results indicate that charcoal strongly assists seed germination and physiological activity.  相似文献   

2.
Buckwheat (Fagopyrum esculentum Moench. cv Jianxi) is highly resistant to Al stress and is known to be an Al-accumulator. Pot experiments were carried out in a greenhouse to investigate the accumulation of Al in leaves and seeds of buckwheat. Plants were grown for 12 weeks in a strong acid soil amended with or without CaCO3 at a rate of 1 g kg−1 soil. Old leaves accumulated as much as 10 g kg−1 Al of dry weight when the plants were grown in the acid soil, while the Al concentrations in leaves immediately adjacent to seeds, seed coats, and embryos were, on average, 4516, 41.2 and 7.7 mg kg−1, respectively. The Al concentration significantly decreased in leaves when the plants were grown in the limed soil, and the Al concentrations in leaves immediately adjacent to seeds, seed coats, and embryos were, on average, 1586, 21.3 and 3.1 mg kg−1, respectively. These results show that seeds accumulate much less Al than buckwheat leaves. The underlying mechanisms are discussed. Section Editor: H. Lambers  相似文献   

3.
To obtain basic information for evaluating critical loads of acid deposition for protecting Japanese beech forests, growth, net photosynthesis and leaf nutrient status of Fagus crenata seedlings grown for two growing seasons in brown forest soil acidified with H2SO4 or HNO3 solution were investigated. The whole-plant dry mass of the seedlings grown in the soil acidified by the addition of H2SO4 or HNO3 solution was significantly less than that of the seedlings grown in the control soil not supplemented with H+ as H2SO4 or HNO3 solution. However, the degrees of reduction in the whole-plant dry mass and net photosynthetic rate of the seedlings grown in the soil acidified by the addition of H+ as H2SO4 solution at 100 mg l–1 on the basis of air-dried soil volume (S-100 treatment) were greater than those of the seedlings grown in the soil acidified by the addition of H+ as HNO3 solution at 100 mg l–1 (N-100 treatment). The concentrations of Al and Mn in the leaves of the seedlings grown in the S-100 treatment were significantly higher than those in the N-100 treatment. A positive correlation was obtained between the molar ratio of (Ca+Mg+K)/(Al+Mn) in the soil solution and the relative whole-plant dry mass of the seedlings grown in the acidified soils to that of the seedlings grown in the control soil. Based on the results, we concluded that the negative effects of soil acidification due to sulfate deposition are greater than those of soil acidification due to nitrate deposition on growth, net photosynthesis and leaf nutrient status of F. crenata, and that the molar ratio of (Ca+Mg+K)/(Al+Mn) in soil solution is a suitable soil parameter for evaluating critical loads of acid deposition in efforts to protect F. crenata forests in Japan.  相似文献   

4.
Effects of selenium (Se) on growth and some physiological traits of roots in wheat (Triticum aestivum L. cv Han NO.7086) seedlings exposed to enhanced ultraviolet-B (UV-B) stress are reported. Responses of roots were different depending on the Se concentration. Compared with the control, root weight of wheat seedlings treated with 1.0 and 2.0 mg Se kg−1 soil increased by 39.47% and 16.28%, respectively. The lower amount Se (0.5 mg kg−1) and the higher amount Se treatments (3.0 mg kg−1) did not significantly affect on root weight. Se treatments significantly increased root activity, flavonoids and proline content, and activities of peroxidase and superoxide dimutase in wheat roots exposed to enhanced UV-B. In addition, the treatments with 0.5, 1.0, and 2.0 mg Se kg−1 significantly reduced malondialdehyde content and the rate of superoxide radical (O2) production of roots, whereas the higher amount Se treatment only induced a decrease in the rate of O2 production. The results of this study demonstrated that optimal Se supply promoted roots growth of wheat seedlings, and that optimal Se supply could reduce oxidative stress in wheat roots under enhanced UV-B radiation.  相似文献   

5.
Silicate (Si) can enhance plant resistance or tolerance to the toxicity of heavy metals. However, it remains unclear whether Si can ameliorate lead (Pb) toxicity in banana (Musa xparadisiaca) roots. In this study, treatment with 800 mg kg−1 Pb decreased both the shoot and root weight of banana seedlings. The amendment of 800 mg kg−1 Si (sodium metasilicate, Na2SiO3·9H2O) to the Pb-contaminated soil enhanced banana biomass at two growth stages significantly. The amendment of 800 mg kg−1 Si significantly increased soil pH and decreased exchangeable Pb, thus reducing soil Pb availability, while Si addition of 100 mg kg−1 did not influence soil pH. Results from Pb fractionation analysis indicated that more Pb were in the form of carbonate and residual-bound fractions in the Si-amended Pb-contaminated soils. The ratio of Pb-bound carbonate to the total Pb tended to increase with increasing growth stages. Treatment with 100 mg kg−1 Si had smaller effects on Pb forms in the Si-amended soils than that of 800 mg kg−1 Si. Pb treatment decreased the xylem sap greatly, but the addition of Si at both levels increased xylem sap and reduced Pb concentration in xylem sap significantly in the Si-amended Pb treatments. The addition of Si increased the activities of POD, SOD, and CAT in banana roots by 14.2% to 72.1% in the Si-amended Pb treatments. The results suggested that Si-enhanced tolerance to Pb toxicity in banana seedlings was associated with Pb immobilization in the soils, the decrease of Pb transport from roots to shoots, and Si-mediated detoxification of Pb in the plants.  相似文献   

6.
The effect of Si(OH)4 on Cr toxicity and elemental concentrations in ryegrass were investigated in a growth chamber using an acid and a neutral mineral soil. Each soil was treated with 50 mg Cr, as CrO3, kg−1 soil dry weight, singly, or in combination with 25 mg Si as Si(OH)4. Plants growing in unamended soils were used as controls. Chromium toxicity, expressed as decrease in shoot or root dry weight, was increased by the Si. This increase was accompanied by a higher Cr uptake particularly on the acid soil. The shoot and root dry weights were significantly correlated (P=1%) with the concentration of Cr, where r=−0.80 and −0.65, respectively. Uptake of Al, Cu, Fe, P and Zn did not show any consistent relationship to the magnitude of Cr toxicity.  相似文献   

7.
The paper reports the effects of selenium (Se) supply on growth and antioxidant traits of wheat (Triticum aestivum L. cv Han NO.7086) seedlings exposed to enhanced ultraviolet-B (UV-B) stress. Antioxidant responses of seedlings were different depending on the Se concentration. Compared with the control, the lower amount used (0.5 mg Se kg−1 soil) had no significant effect on biomass accumulation. The treatments with 1.0, 2.0, and 3.0 mg Se kg−1 promoted biomass accumulation of wheat seedlings, and the increased amount in biomass was the most at 1.0 mg Se kg−1 treatment. Se treatments with 1.0, 2.0, and 3.0 mg kg−1 also significantly increased activities of peroxidase (POD) and superoxide dismutase (SOD) and reduced the rate of superoxide radical (O2) production and malondialdehyde (MDA) content of wheat seedlings. In addition, anthocyanins and phenolic compounds content in wheat seedlings evidently increased by the treatments with 1.0 and 2.0 mg Se kg−1. The lower Se treatment had no significant effect on MDA content, although it increased activities of antioxidant enzymes (POD, SOD, and catalase activities) and reduced the rate of O2 production in wheat seedlings. These results suggest that optimal Se supply is favorable for the growth of wheat seedlings and that optimal Se supply can reduce oxidative stress of seedlings under enhanced UV-B radiation.  相似文献   

8.
9.
The plainfin midshipman (Porichthys notatus) possesses an aglomerular kidney and like other marine teleosts, secretes base into the intestine to aid water absorption. Each of these features could potentially influence acid–base regulation during respiratory acidosis either by facilitating or constraining HCO3 accumulation, respectively. Thus, in the present study, we evaluated the capacity of P. notatus to regulate blood acid–base status during exposure to increasing levels of hypercapnia (nominally 1–5% CO2). Fish exhibited a well-developed ability to increase plasma HCO3 levels with values of 39.8 ± 2.8 mmol l−1 being achieved at the most severe stage of hypercapnic exposure (arterial blood PCO2 = 21.9 ± 1.7 mmHg). Consequently, blood pH, while lowered by 0.15 units (pH = 7.63 ± 0.06) during the final step of hypercapnia, was regulated far above values predicted by chemical buffering (predicted pH = 7.0). The accumulation of plasma HCO3 during hypercapnia was associated with marked increases in branchial net acid excretion (J NETH+) owing exclusively to increases in the titratable alkalinity component; total ammonia excretion was actually reduced during hypercapnia. The increase in J NETH+ was accompanied by increases in branchial carbonic anhydrase (CA) enzymatic activity (2.8×) and CA protein levels (1.6×); branchial Na+/K+-ATPase activity was unaffected. Rectal fluids sampled from control fish contained on average HCO3 concentrations of 92.2 ± 4.8 mmol l−1. At the highest level of hypercapnia, rectal fluid HCO3 levels were increased significantly to 141.8 ± 7.4 mmol l−1 but returned to control levels during post-hypercapnia recovery (96.0 ± 13.2 mmol l−1). Thus, the impressive accumulation of plasma HCO3 to compensate for hypercapnic acidosis occurred against a backdrop of increasing intestinal HCO3 excretion. Based on in vitro measurements of intestinal base secretion in Ussing chambers, it would appear that P. notatus did not respond by minimizing base loss during hypercapnia; the increases in base flux across the intestinal epithelium in response to alterations in serosal HCO3 concentration were similar in preparations obtained from control or hypercapnic fish. Fish returned to normocapnia developed profound metabolic alkalosis owing to unusually slow clearance of the accumulated plasma HCO3 . The apparent inability of P. notatus to effectively excrete HCO3 following hypercapnia may reflect its aglomerular (i.e., non-filtering) kidney coupled with the normally low rates of urine production in marine teleosts.  相似文献   

10.
The aim of this work is to develop a method of plant regeneration from leaf explants of Platanus occidentalis L. successfully. Woody plant medium (HortScience 16:453–459, 1981) and Murashige and Skoog (Physiol Plant 15:473–497, 1962) medium were used as induced and rooted basal medium, respectively. The effects of combinations of 6-BA, IBA, NAA and KT with different concentrations on adventitious bud regeneration from P. occidentalis leaf explants were compared. The results showed that the highest shoot regeneration frequency (90%) and maximum number (13.72 ± 0.44) of shoots per explant was recorded on WPM medium supplemented with 22.20 mmol l−1 6-BA and 0.49 mmol l−1 IBA. A 40-day-old explants were much more productive for shoot formation than others in this study. The regenerated shoots were cultured on MS medium supplemented with 1.33 mmol l−1 6-BA, 0.16 mmol l−1 NAA and 2% (w/v) adenine, after 2-week shoots were transferred to 1/2 MS medium supplemented with 0.49 mmol l−1 IBA for rooting. Hardened plantlets via acclimatization were transferred to pots and transplanted to the soil finally. To ascertain whether tissue culture had effects on the genetic stability of plantlets regenerated, the genetic diversity was assessed using RAPD marker. A total of 96 bands ranging from 0.5 to 2.2 kb with an average of 6.4 bands per primer, were obtained using 15 primers. Amplified products exhibited few of polymorphic patterns across all the plants of P. occidentalis and the overall frequency of detection of somaclonal polymorphisms was lower than 0.0104%. Yuehua Sun, Yanling Zhao, and Xiaojuan Wang contributed equally to this work.  相似文献   

11.
The activity of Na+/H+ exchanger to remove toxic Na+ is important for growth of organisms under high salinity. In this study, the halotolerant cyanobacterium Aphanothece halophytica was shown to possess Na+/H+ exchange activity since exogenously added Na+ could dissipate a pre-formed pH gradient, and decrease extracellular pH. Kinetic analysis yielded apparent K m (Na+) and V max of 20.7 ± 3.1 mM and 3,333 ± 370 nmol H+ min−1 mg−1, respectively. For cells grown under salt-stress condition, the apparent K m (Na+) and V max was 18.3 ± 3.5 mM and 3,703 ± 350 nmol H+ min−1 mg−1, respectively. Three cations with decreasing efficiency namely Li+, Ca2+, and K+ were also able to dissipate pH gradient. Only marginal exchange activity was observed for Mg2+. The exchange activity was strongly inhibited by Na+-gradient dissipators, monensin, and sodium ionophore as well as by CCCP, a protonophore. A. halophytica showed high Na+/H+ exchange activity at neutral and alkaline pH up to pH 10. Cells grown at pH 7.6 under high salinity exhibited higher Na+/H+ exchange activity than those grown under low salinity during 15 days of growth suggesting a role of Na+/H+ exchanger for salt tolerance in A. halophytica. Cells grown at alkaline pH of 9.0 also exhibited a progressive increase of Na+/H+ exchange activity during 15 days of growth.  相似文献   

12.
Rhodopseudomonas palustris TN1 was isolated from Songkhla Lake, Thailand. It phototrophically generates H2 from the predominant volatile fatty acids (VFAs) produced from microbial dark-fermentations of palm oil milling effluent; yields from 20 mM butyrate, acetate and propionate were 4.7, 2.5, and 1.7 mol H2 mol VFA−1 with light efficiencies of 1.8, 1, and 0.2%, respectively. Optimum conditions were pH 7 and 3000 lux, although production was reduced by only 33% at 1000 lux. CO2 evolution never exceeded 9 mmol mol VFA−1.  相似文献   

13.
The impacts of global climatic change on belowground ecological processes of terrestrial ecosystems are still not clear. We therefore conducted an experiment in the subalpine coniferous forest ecosystem of the eastern edges of the Tibetan Plateau to study roots of Picea asperata seedlings and rhizosphere soil responses to soil warming and nitrogen availability from April 2007 to December 2008. The seedlings were subjected to two levels of temperature (ambient; infrared heater warming) and two nitrogen levels (0 or 25 g m−2year−1 N). We used a free air temperature increase from an overhead infrared heater to raise both air and soil temperature by 2.1 and 2.6°C, respectively. The results showed that warming alone significantly increased total biomass, coarse root biomass and fine root biomass of P. asperata seedlings. Both total biomass and fine root biomass were increased, but coarse root biomass was significantly decreased by nitrogen fertilization and warming combined with nitrogen fertilization. Warming induced a prominent increase in soil organic carbon (SOC) and NO3 -N of rhizosphere soil, while nitrogen fertilization significantly decreased SOC and NH4 +-N of rhizosphere soil. The warming, fertilization and warming × N fertilization interaction decreased soil microbial C significantly, but substantially increased soil microbial N. These results suggest that nitrogen deposition combined with warmer temperatures under future climatic change possibly will have no effect on fine root production of P. asperata seedlings, but could enhance the nitrification process of their rhizosphere soils in subalpine coniferous forests.  相似文献   

14.
Variations of soil enzyme activities in a temperate forest soil   总被引:3,自引:0,他引:3  
Kang  Hojeong  Kang  Sinkyu  Lee  Dowon 《Ecological Research》2009,24(5):1137-1143
Soil enzyme activities (dehydrogenase, urease, phosphatase, and arylsulfatase) in a temperate forest soil were determined in relation to landscape position and seasons. Overstory of the area is dominated by Quercus mongolica, Kalopanax pictus, Carpicus cordata, and Acer pseudo-sieboldianum. The activities were measured in three patches, namely a north-facing backslope, a ridge, and a south-facing backslope in autumn and spring over 2 years. In addition, spatially more detailed analysis for phosphatase was conducted before and after litterfall production in six patches. Dehydrogenase, urease, phosphatase, and arylsulfatase activities varied 1.8–18.5 μg INT-formazan g−1 h−1, 45.4–347.0 μg NH4 + g−1 h−1, 0.9–4.5 mmol pNP g−1 h−1, and 0.7–2.6 mmol pNP g−1 h−1, respectively. In general, higher enzyme activities were found in the northern aspect than in the southern aspect. This variation appears to be related to differences in chemical properties (e.g., Fe, Al, and Mg) of soil as well as distribution of leaf litter. Two patterns were discernible in relation to seasonal variations. Dehydrogenase and urease exhibited a positive correlation with mean air temperature, suggesting that temperature would be a major controlling variable for those enzymes. In contrast, higher activities were detected in autumn for phosphatase and arylsulfatase activities, which appeared to be closely related to litter production and distribution. Overall results of this study indicate that soil enzyme activities in a forest floor are influenced by several variables such as temperature, nutrient availability, and input of leaf litter, which are closely related to landscape position.  相似文献   

15.
16.
The failure of Vigna luteola L. to colonize tropical montane regions of Venezuela with acid P-deficient soils that lack vegetation has been mainly attributed to the inability of indigenous arbuscular mycorrhizal fungi (AMFi) to be effective suppliers of P to this host plant. To test this hypothesis, Vigna luteola plants were grown in non sterile soil collected from this habitat. Plants became nodulated by indigenous rhizobia (Nod+) and the roots were colonized by AMFi (AMFi+). Some plants were inoculated with the arbuscular mycorrhizal fungus Rhizophagus manihotis (AMFg+). Other plants were fertilized with 6 mM nitrate and 2 mM P to inhibit nodulation (Nod-) and AMFi colonization (AMFi-), respectively and these served as controls. The Nod+AMFi+ plants displayed the smallest shoot and nodule dry weights upon harvest, the poorest AMF colonization, lowest foliar mineral content (N, P, Mg, Mn, Fe, Zn, and Cu), highest leaf ureide concentrations and lowest soil dehydrogenase, urease and acid phosphatase activities. Greater growth, nodulation, nutrient uptake, photosynthesis, catabolism of ureides in leaves, leaf superoxide dismutase and soil enzymatic activities were found in Nod+AMFg+ plants. The Nod-AMFg+ plants grew even better attributed to their higher P uptake that was allocated mainly to the photosynthetic apparatus rather than to N2-fixation. The results showed that V. luteola plants inoculated with R. manihotis and nodulated by indigenous rhizobia are capable successfully of colonizing open montane regions devoid of ground cover vegetation. The Nod+AMFg+ plants had greater growth, nodulation and root colonization by AMFg resulting in improved nutrient condition, enhanced uptake of nitrate and high catabolism of ureides in leaves than Nod+AMFi+ plants. However, more research is needed before the inoculation of open montane regions with AMFg can be recommended to land managers since a) the enhanced N2 fixation rate in Nod+AMFg+ plants have an extra cost of 1.2 mg P kg−1 leaf dry weight plant−1 which could places an extra burden on the plants grown in the P-deficient soils, and b) the possible impact of AMFg on the microbiology of these former forest soils must be assessed.  相似文献   

17.
This study was designed to identify rhizobial strains specific to greengram expressing higher tolerance against insecticides, fipronil and pyriproxyfen, and synthesizing plant growth regulators even amid insecticide-stress. Of the 50 bradyrhizobial isolates, the Bradyrhizobium sp. strain MRM6 showed tolerance up to 1,600 μg mL−1 against each of fipronil and pyriproxyfen. The tolerant Bradyrhizobium sp. (vigna) produced plant growth promoting substances in substantial amounts, both in the presence and absence of insecticides. The strain MRM6 was further used to investigate its impact on greengram grown in soils treated with 200 (the recommended dose), 400 and 600 μg kg−1 soil of fipronil and 1,300 (the recommended dose), 2,600 and 3,900 μg kg−1 soil of pyriproxyfen. Fipronil at 600 μg kg−1 soils and pyriproxyfen at 3,900 μg kg−1 soils had greatest toxic effects and decreased plant biomass, symbiotic efficiency, nutrient uptake and seed yield of greengram plants. The Bradyrhizobium sp. (vigna) inoculant when used with fipronil and pyriproxyfen significantly increased the measured parameters compared to the plants grown in soils treated solely with the same concentration of each insecticide. This study inferred that the Bradyrhizobium sp. (vigna) strain MRM6 may be exploited as bio-inoculant to increase the productivity of greengram exposed to insecticide-stressed soils.  相似文献   

18.
In order to characterise the effect of ectomycorrhiza on Na+-responses of the salt-sensitive poplar hybrid Populus × canescens, growth and stress responses of Paxillus involutus (strain MAJ) were tested in liquid cultures in the presence of 20 to 500 mM NaCl, and the effects of mycorrhization on mineral nutrient accumulation and oxidative stress were characterised in mycorrhizal and non-mycorrhizal poplar seedlings exposed to 150 mM NaCl. Paxillus involutus was salt tolerant, showing biomass increases in media containing up to 500 mM NaCl after 4 weeks growth. Mycorrhizal mantle formation on poplar roots was not affected by 150 mM NaCl. Whole plant performance was positively affected by the fungus because total biomass was greater and leaves accumulated less Na+ than non-mycorrhizal plants. Energy dispersive X-ray microanalysis using transmission electron microscopy analysis of the influence of mycorrhization on the subcellular localisation of Na+ and Cl in roots showed that the hyphal mantle did not diminish salt accumulation in root cell walls, indicating that mycorrhization did not provide a physical barrier against excess salinity. In the absence of salt stress, mycorrhizal poplar roots contained higher Na+ and Cl concentrations than non-mycorrhizal poplar roots. Paxillus involutus hyphae produced H2O2 in the mantle but not in the Hartig net or in pure culture. Salt exposure resulted in H2O2 formation in cortical cells of both non-mycorrhizal and mycorrhizal poplar and stimulated peroxidase but not superoxide dismutase activities. This shows that mature ectomycorrhiza was unable to suppress salt-induced oxidative stress. Element analyses suggest that improved performance of mycorrhizal poplar under salt stress may result from diminished xylem loading of Na+ and increased supply with K+.  相似文献   

19.
Sparse Ulmus pumila woodlands play an important role in contributing to ecosystem function in semi-arid grassland of northern China. To understand the key attributes of soil carbon cycling in U. pumila woodland, we studied dynamics of soil respiration in the canopy field (i.e., the projected crown cover area) and the open field at locations differing in distance (i.e., at 1–1.5, 3–4, 10, and >15 m) to tree stems from July through September of 2005, and measured soil biotic factors (e.g., fine root mass, soil microbial biomass, and activity) and abiotic factors [e.g., soil water content (SWC) and organic carbon] in mid-August. Soil respiration was further separated into root component and microbial component at the end of the field measurement in September. Results showed that soil respiration had a significant exponent relationship with soil temperature at 10-cm depth. The temperature sensitivity index of soil respiration, Q 10, was lower than the global average of 2.0, and declined significantly (P < 0.05) with distance. The rate of soil respiration was generally greater in the canopy field than in the open field; monthly mean of soil respiration was 305.5–730.8 mg CO2 m−2 h−1 in the canopy field and 299.6–443.1 mg CO2 m−2 h−1 in the open field from July through September; basal soil respiration at 10°C declined with distance, and varied from ~250 mg CO2 m−2 h−1 near tree stems to <200 mg CO2 m−2 h−1 in the open field. Variations in soil respiration with distance were consistent with patterns of SWC, fine root mass, microbial biomass and activities. Regression analysis indicated that soil respiration was tightly coupled with microbial respiration and only weakly related to root respiration. Overall, variations in SWC, soil nutrients, microbial biomass, and microbial activity are largely responsible for the spatial heterogeneity of soil respiration in this semi-arid U. pumila woodland.  相似文献   

20.
In a pot-soil culture ameliorative effect of sulphur (S) (0 or 40 mg S kg−1 soil) on cadmium (Cd) (0, 25, 50 and 100 mg Cd kg−1 soil)-induced growth inhibition and oxidative stress in mustard (Brassica campestris L.) cultivar Pusa Gold was studied. Cadmium at 100 mg kg−1 soil caused maximum increase in the contents of Cd and thiobarbituric acid reactive substances (TBARS) in leaves. Maximum reductions in growth (plant dry mass, leaf area), chlorophyll content, net photosynthetic rate (PN) and the contents of ascorbate (AsA), glutathione (GSH) were observed with 100 mg Cd kg−1 soil compared to control. The application of S helped in reducing Cd toxicity, which was greater for 25 and 50 mg Cd kg−1 soil) compared to 100 mg Cd kg−1 soil. Addition of S to Cd-treated plants showed decrease in Cd and TBARS content in leaves and restoration of growth and photosynthesis through increase in the contents of AsA and GSH. Net photosynthetic rate and plant dry mass were strongly and positively correlated with the contents of AsA and GSH. It is suggested that S may ameliorate Cd toxicity and protects growth and photosynthesis of mustard involving AsA and GSH.  相似文献   

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