Shoot Uptake Research Articles

Endogenous salicylic acid is required for promoting cadmium tolerance of Arabidopsis by modulating glutathione metabolisms

A few studies with NahG transgenic lines of Arabidopsis show that depletion of SA enhances cadmium (Cd) tolerance. However, it remains some uncertainties that the defence signaling may be a result of catechol accumulation in NahG transgenic lines but not SA deficiency. Here, we conducted a set of hydroponic assays with another SA-deficient mutant sid2 to examine the endogenous roles of SA in Cd tolerance, especially focusing on the glutathione (GSH) cycling. Our results showed that reduced SA resulted in negative effects on Cd tolerance, including decreased Fe uptake and chlorophyll concentration, aggravation of oxidative damage and growth inhibition. Cd exposure significantly increased SA concentration in wild-type leaves, but did not affect it in sid2 mutants. Depletion of SA did not disturb the Cd uptake in either roots or shoots. The reduced Cd tolerance in sid2 mutants is due to the lowered GSH status, which is associated with the decreased expression of serine acetyltransferase along with a decline in contents of non-protein thiols, phytochelatins, and the lowered transcription and activities of glutathione reductase1 (GR1) which reduced GSH regeneration. Finally, the possible mode of SA signaling through the GR/GSH pathway during Cd exposure is discussed.

Improvement of crop yield by phosphate-solubilizing Aspergillus species in organic farming

ABSTRACTPhosphate-solubilizing fungal strains were isolated from organically managed soil and tested for their ability to solubilize rock phosphate (RP), ferric phosphate and aluminium phosphate. These strains were identified as Aspergillus tubingensis and Aspergillus niger based on internal transcribed spacer sequence analysis. A field study was conducted in two different seasons in organically managed soil to test the efficacy of two strains, A. tubingensis (PSF-4) and A. niger (PSF-7) on the yield and soil fertility. RP was amended at the rate of 59 kg P2O5 ha−1 to study the effect of RP on soil fertility. The maize was grown in rainy season (July–October 2011) and wheat in winter season (November 2011–April 2012). Plant heights, shoot and root dry biomass and phosphorous (P) uptake in roots, shoots and grains were significantly increased due to inoculation in both crops. The yield of maize and wheat were significantly increased when inoculated along with RP fertilization. Organic carbon, P levels and soil enzyme activities were significantly increased due to inoculation. Results of present study suggested that A. tubingensis and A. niger improved the crop yield and soil fertility of organic farm when inoculated with RP fertilization.

Different genotypes of Silene vulgaris (Moench) Garcke grown on chromium-contaminated soils influence root organic acid composition and rhizosphere bacterial communities.

Plant-microbe interactions are considered to be important processes determining the efficiency of phytoremediation of heavy metal-contaminated soils. However, relatively little is known about how these interactions are influenced by chromium (Cr) contamination. The effect of Cr stress on metal uptake, root organic acid composition, and rhizosphere bacterial communities was studied using two genotypes of the metallophyte Silene vulgaris, which have shown different tolerance to Cr(VI). The results indicated that root biomass and shoot biomass were not significantly influenced by Cr treatment, but metal uptake in shoots and roots was significantly impacted by the genotype. Principal component analyses (PCA) showed that variation in organic acids oxalic, citric, malic, formic, lactic, acetic, and succinic differed between genotypes. Changes in root organic acid contents in response to Cr revealed a significant increase of oxalic acid in genotype SV-21. The denaturing gradient gel electrophoresis (DGGE) cluster analysis showed that the community structure (determined by PCR-DGGE) was affected by plant genotype and, to a lesser extent, by Cr contamination, the first being the most influential factor shaping the rhizosphere microbiome. Under Cr pollution, a shift in the relative abundance of specific taxa was found and dominant phylotypes were identified as Variovorax in SV-21 and Chitinophaga niastensis, Pontibacter sp., and Ramlibacter sp. in SV-38. These results provided the basis for further studies aimed at the combined use of plants and soil microorganisms in the remediation of Cr-polluted soils.

Selenium-rich dissolved organic matter determines selenium uptake in wheat grown on Low-selenium arable land soils

The study aimed to find soil parameters that are best related to Se plant uptake for low Se soils with predominantly organic Se, and to explore the mechanisms that control Se bioavailability in the soils under study. A pot experiment using nineteen soil samples taken from different fields of arable land (potato fields) in the Netherlands was conducted on summer wheat (Triticum aestivum L.). Selenium in wheat shoots and soil parameters, including basic soil properties, C:N ratio, inorganic selenite content, and Se and organic C in different soil extractions (0.01 M CaCl2, 0.43 M HNO3, hot water, ammonium oxalate, aqua regia) were analysed. Regression analysis was performed to identify soil parameters that determine Se content in wheat shoots. The regression model shows that Se:DOC ratio in 0.01 M CaCl2 soil extraction explained about 88 % of the variability of Se uptake in wheat shoots. Selenium uptake increased with Se:DOC ratio in CaCl2 extraction, which can be interpreted as a measure of the content of soluble Se-rich organic molecules. Selenium:DOC ratio in CaCl2 extraction and Se uptake increased towards higher soil pH and lower soil C:N ratio. The soil C:N ratio is also negatively correlated to Se:organic C ratio in other extractions (0.43 M HNO3, hot water, ammonium oxalate, aqua regia), indicating that at low soil C:N ratio soil organic matter is richer in Se. Contrarily, the soil pH is positively and strongly correlated to Se:organic C ratio in CaCl2 and hot water extractions, but only weakly correlated to Se:organic C ratio in other extractions. Selenium-rich dissolved organic matter is the source of bioavailable Se in low Se soils with predominantly organic Se. The soil pH and quality of soil organic matter (i.e. soil C:N ratio) are the main soil properties determining Se bioavailability in these soil types.

Comparative potentials of native arbuscular mycorrhizal fungi to improve nutrient uptake and biomass of Sorghum bicolor Linn

Sorghum (Sorghum bicolor Linn.) seedlings were grown in pots using Pakchong soil from Nakhon Ratchasima province. Ten species of native Arbuscular mycorrhizal (AM) fungi: Glomus sp. 1, Glomus sp. 2, Glomus sp. 3, Glomus aggregatum, Glomus fasciculatum, Acaulospora longula, Glomus occultum, Acaulospora scrobiculata, Acaulospora spinosa and Scutellospora sp., were used to inoculate sorghum seedlings. The sorghum growth and uptake of several major nutrients were evaluated at the harvesting stage. The results revealed that sorghum inoculated with A. scrobiculata produced the greatest biomass, grain dry weight and total nitrogen uptake in shoots. The highest phosphorus uptake in shoots was found in A. spinosa-inoculated plants, followed by Glomus sp. and A. scrobiculata, whereas Scutellospora sp.-inoculated plants showed the highest potassium uptake in shoots followed by A. scrobiculata. Overall, the most efficient AM fungi for improvement of nutrient uptake, biomass and grain dry weight in sorghum were A. scrobiculata.

Influence of plant growth regulators and humic acid on the phytoremediation of lead by maize in a Pb-polluted calcareous soil

ABSTRACTPhytoremediation is a cleanup technology for the removal of contaminants from polluted soils. The influences of humic acid (HA) and four plant growth regulators, i.e. gibberellic acid, salicylic acid, 3-indoleacetic acid, and 6-benzylaminopurine on the phytoremediation of Pb by maize were investigated in a pot trial on a Pb-contaminated soil. Foliar spray of 6-benzylaminopurine and salicylic acid significantly increased mean root dry matter but none of growth regulators had a significant effect on that of shoot. Addition of HA decreased root dry matter and had no significant effect on that of shoots. Application of all growth regulators except gibberellic acid significantly increased root Pb uptake. Application of salicylic acid significantly increased mean uptake efficiency and shoot Pb concentration and uptake. Although addition of HA significantly increased mean phytoextraction and translocation efficiencies, these responses were mainly attributed to the role of HA in the reduction of both root dry weight and Pb uptake, meaning that HA is not promising in Pb phytoremediation by maize. Among the four plant growth regulators evaluated, salicylic acid was the most effective in enhancing phytoremediation through phytostabilization of Pb.

The influence of iron chelate and zinc sulfate on the growth and nutrient composition of chickpea grown on a calcareous soil

ABSTRACT- The effects of iron (Fe) and zinc (Zn) treatments on the growth and nutrient composition of chickpea were studied in a greenhouse experiment arranged in a completely randomized design. While the application of Fe decreased mean shoot dry weight of chickpea, that of Zn had no significant effect on chickpea shoot dry weight. Increasing Fe levels drastically decreased Mn concentration and uptake in chickpea shoot. Addition of Zn, however, had no significant effect on Mn concentration and uptake in chickpea shoot. Although the addition of 10 mg Fe kg-1 significantly increased mean Fe concentration in chickpea shoot, the effect of Fe application on mean Fe uptake was negligible. Although the application of Zn had no significant effect on mean Fe concentration or uptake, it increased mean Zn uptake in chickpea shoot. While the application of Fe increased mean Zn concentration, application of 5 mg Fe kg-1 had no significant effects on mean Cu concentration or uptake in chickpea tissues although 10 mg Fe kg-1 increased mean Cu concentration and uptake in chickpea tissues. Addition of Zn, however, had no significant effect on Cu uptake. A significant negative correlation was observed between Mn uptake and Fe rates demonstrating a reduction in shoot Mn uptake following Fe application. Although shoot dry weight of chickpea was negatively correlated with Fe rates, it showed significant positive correlations with the uptakes of Zn and Mn indicating that the patterns of changes in dry matter was in coordination with changes in Zn and Mn uptakes. Since Fe chelate addition may cause nutrient imbalance and growth reduction in chickpea, it appears that the use of Fe and Zn efficient genotypes should be considered as an appropriate practice for chickpea grown on calcareous soils low in available Fe and Zn.

Cadmium toxicity and soil biological index under potato (Solanum tuberosum L.) cultivation

Increasing cadmium (Cd) pollution in soil is of great concern. A pot experiment was conducted with the aim of assessing the effect of Cd on soil biological indices under potato cultivation. Cadmium was added to 10 kg soil in each pot (6 seeds pot–1) as Cd(NO3)2 at 0, 15, 30, 45 and 60 mg kg–1 with three replications. All soil and plant parameters decreased with all Cd treatments; however, high levels of Cd had a significant (P < 0.05) suppressive effect. The highest Cd level significantly (P < 0.05) decreased microbial biomass carbon (2.16-fold), nitrogen (11.37-fold) and phosphorus (10.3-fold), as well as enzyme activities of dehydrogenase (4.36-fold), phosphatase (9.23-fold), and urease (9.61-fold). The highest Cd level also decreased pH (1.46-fold), potato shoot (3.55-fold) and root (7.43-fold) length, root (10.9-fold) and shoot (6.04-fold) fresh weight, root (7.51-fold) and shoot (13.7-fold) dry weight, chlorophyll content (27.0-fold), carotenoid content (4.08-fold), and plant macronutrient and micronutrient uptake in potato root and shoots. Conversely, the highest level of Cd significantly (P < 0.05) increased the biomass C : N (5.27-fold) and C : P (4.77-fold) ratios, soil extractable Cd (5.38-fold), and Cd uptake in potato root (5.05-fold) and shoot (4.82-fold) at the end of the experiment (day 60). Cadmium contamination substantially affected soil biological indices and growth of potato, and the Cd threshold was strongly associated with the extent of Cd concentration and duration to accumulate. Soil microbial biomass, enzymatic activities, pH and potato physiological parameters could be used as a sensitive indicators to reflect environmental stresses in soil ecosystems.

Effectiveness of arbuscular mycorrhizal fungi in phytoremediation of lead- contaminated soil by vetiver grass

ABSTRACTA greenhouse experiment was conducted to evaluate the effectiveness of arbuscular mycorrhizal (AM) fungi in phytoremediation of lead (Pb)-contaminated soil by vetiver grass. Experiment was a factorial arranged in a completely randomized design. Factors included four Pb levels (50, 200, 400, and 800 mg kg−1) as Pb (NO3)2, AM fungi at three levels (non mycorrhizal (NM) control, Rhizophagus intraradices, Glomus versiforme). Shoot and root dry weights (SDW and RDW) decreased as Pb levels increased. Mycorrhizal inoculation increased SDW and RDW compared to NM control. With mycorrhizal inoculation and increasing Pb levels, Pb uptake of shoot and root increased compared to those of NM control. Root colonization increased with mycorrhizal inoculation but decreased as Pb levels increased. Phosphorus concentration and uptake in shoot of plants inoculated with AM fungi was significantly higher than NM control at 200 and 800 mg Pb kg−1. The Fe concentration, Fe and Mn uptake of shoot in plants inoculated with Rhizophagus intraradices in all levels of Pb were significantly higher than NM control. Mycorrhizal inoculation increased Pb extraction, uptake and translocation efficiencies. Lead translocation factor decreased as Pb levels increased; however inoculation with AM fungi increased Pb translocation.

Effect of simulated climate warming on the morphological and physiological traits of Elsholtzia haichowensis in copper contaminated soil

ABSTRACTThe aim of this study was to investigate the effects of temperature and Cu on the morphological and physiological traits of Elsholtzia haichowensis grown in soils amended with four Cu concentrations (0, 50, 500, and 1000 mg kg−1) under ambient temperature and slight warming. At the same Cu concentration, the height, shoot dry weight, total plant dry weight, and root morphological parameters such as length, surface area and tip number of E. haichowensis increased due to the slight warming. The net photosynthetic rate, stomatal conductance, transpiration, light use efficiency were also higher under the slight warming than under ambient temperature. The increased Cu concentrations, total Cu uptake, bioaccumulation factors and tolerance indexes of shoots and roots were also observed at the slight warming. The shoot dry weight, root dry weight, total plant dry weight and the bioaccumulation factors of shoots and roots at 50 mg Cu kg−1 were significantly higher than those at 500 and 1000 mg Cu kg−1 under the slight warming. Therefore, the climate warming may improve the ability of E. haichowensis to phytoremediate Cu-contaminated soil, and the ability improvement greatly depended on the Cu concentrations in soils.

Effect of Funneliformis mosseae on the growth, cadmium accumulation and antioxidant activities of Solanum nigrum

Arbuscular mycorrhizal (AM) fungi can promote plant growth and resistance to heavy metal (HM), affect HM bioavailability and uptake by plants, and thus have been considered as the most prominent symbiotic fungi for contribution to phytoremediation. A greenhouse pot experiment was performed to assess the effects of Funneliformis mosseae BGC XJ02 (Fm) on the plant growth, P acquisition, Cd accumulation, phytochelatins (PCs) production and antioxidant activities of Cd-hyperaccumulator Solanum nigrum in different Cd-added soils (0, 5, 10, 20 and 40mgCdkg−1soil). Fm associated with S. nigrum very well, and mycorrhizal colonizations were not influenced by Cd addition. Fm inoculation significantly increased P acquisition, plant growth, Cd concentration and Cd uptake in both shoots and roots of S. nigrum at all Cd levels. The improvement of catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POD) activities in the leaves of mycorrhizal plants suggested that Fm colonization helped S. nigrum to relieve oxidative damage to biomolecules in Cd-contaminated soil. Moreover, glutathione reductase (GR) activities in the leaves of mycorrhizal plants were elevated (from 17% to 99%) in lower Cd levels (0, 5 and 10mgCdkg−1 soil), but reduced in higher Cd levels (20 and 40mgCdkg−1 soil). The obvious decrease of malonaldehyde (MDA) content in the leaves of mycorrhizal plants displayed that Fm symbiosis significantly enhanced antioxidant activities. In conclusion, Fm symbiosis alleviated Cd phytotoxicity to S. nigrum through the improvement of P acquisition and activities of CAT, POD, APX in mycorrhizal plants, and then improved plant growth and phytoremediation efficiency for Cd-contaminated soil.

EFFECTS OF PLANT GROWTH PROMOTING RHIZOBACTERIA ON SUMMER SQUASH GROWTH, YIELD, NUTRIENTS UPTAKE AND AVAILABILITY UNDER NITROGEN AND PHOSPHORUS FERTILIZATION LEVELS

Two field experiments were conducted at the Experimental Research Farm, Faculty of Agriculture, Suez Canal University, Egypt during spring 2013 and 2014 using summer squash (Cucurbita pepo cv. Eskandarani) for studying the effects of PGPR strains. The objective of the first experiment was to study the efficiency of single, double and triple inoculations of Azospirillum brasilense (AC1), Bacillus subtilis (AC2) and Serratia marcescens (BM1) on summer squash fruit characters. Results showed that the double inoculations of tested PGPR strains in addition to single inoculation with Serratia marcescens produced non-significant higher fruit yield and average fruit weight compared to triple inoculation (AC1+AC2+BM1) and single inoculation with Azospirillum brasilense. However, non-inoculated control plants and plants inoculated with Bacillus subtilis showed lower fruit yield and average fruit weight. From the previous results, it concluded that the double inoculation were better than single and triple inoculations. However, the aim of the second experiment was to evaluate the efficiency of PGPR under N and P fertilization levels on plant growth, yield and nutrients uptake of summer squash as well as soil nutrient availability (available N and P). As per main effects, generally, plant growth, fruit yield, nutrients uptake and availability enhanced significantly by increasing N and P levels, except half dose of P which gave statistically equivalent values of plant fresh and dry weight as well as nitrogen uptake in shoots and fruits in addition to P in shoots compared to full dose. Also, main effect of PGPR showed that the inoculated plants gave significantly higher plant growth, fruit yield, nutrient uptake and availability compared to un-inoculated control plants. Inoculated plants with PGPR strains under full dose of N and P gave mostly highest plant growth, fruit yield, nutrients uptake and availability. This effect was at significant level in terms of fruit yield, soil nutrient availability and some nutrients uptake such as K in the shoots and N the fruits. Furthermore, PGPR significantly reduced P fertilizer application without any reduction in squash yield, especially under no and half dose of N fertilizer. Results revealed that the efficiency of PGPR strains increased by P increasing and decreased by N increasing.

Effects of Enriched Biochars Containing Magnetic Iron Nanoparticles on Mycorrhizal Colonisation, Plant Growth, Nutrient Uptake and Soil Quality Improvement

At present, there is little commercial sale of biochar, since farmers find they can not gain a return on their investment in this amendment in the first few years after its application, because of the high cost associated with large application rates. To overcome this constraint, development of artificially aged enriched biochar-mineral complexes (BMCs), having a higher mineral content, surface functionality, exchangeable cations, high concentration of magnetic iron (Fe) nanoparticles, and higher water-extractable organic compounds has been undertaken by a combined team of researchers and a commercial company. Two biochars produced under different pyrolysis conditions were activated with a phosphoric acid treatment. A mixture of clay, chicken litter, and minerals were added to the biochar, and then this composite was torrefied at either 180 or 220 °C. In this study a pot experiment was carried out in glasshouse conditions to determine the effects of four different BMCs, with different formulations applied at rates of 100 and 200 kg ha−1, on the mycorrhizal colonisation, wheat growth and nutrient uptake, and soil quality improvement. It was found that the phosphorus (P) and nitrogen uptake in wheat shoots were significantly greater for a low application rate of BMCs (100 kg ha−1). The present formulation of BMC was effective in enhancing growth of wheat at low application rate (100 kg ha−1). The increase in growth appeared due to an increase in P uptake in the plants that could be partly attributed to an increase in mycorrhizal colonisation and partly due to the properties of the BMC.

Cadmium accumulation and partitioning in Ocimum basilicum as influenced by the application of various potassium fertilizers

Potassium (K) is one of the major essential nutrient elements whose application of organic or nano-chelate-fertilizers has received increased attention recently. Cadmium (Cd) contamination in agricultural soils and environment is increasing due to the over-application of Cd-containing phosphate fertilizers. But few studies have been carried out on the environmental influences of K-nano-chelate fertilizers especially on Cd-polluted soils. Therefore, the effects of K-fertilizer application in different rates (0, 100 and 200 mg kg−1 soil) and forms (KCl, K2SO4 and K-nano-chelate) on Cd content and partitioning in Ocimum basilicum grown on an artificially Cd-contaminated calcareous soil (with 40 mg Cd kg−1 soil) were studied under greenhouse conditions. Cadmium decreased shoot dry weight (SDW), but did not affect root dry weight (RDW) and no consistent trend was observed with applied K. Cadmium increased shoot and root Cd concentration or uptake. KCl and K2SO4 increased shoot Cd concentration compared to that of control, whereas K-nano-chelate did not affect it. In Cd-treated soils the mean value of Cd translocation factor (ratio of Cd concentration in shoots to that of roots) decreased by 60% as compared to that of the control. Application of 100 mg K-K2SO4 and 100 and 200 mg K-nano-chelate increased the Cd translocation factor by 49, 59 and 112% in Cd-treated soils, respectively. In Cd-treated soils, greater amounts of Cd accumulated in roots. K-nano-chelate could mitigate the adverse effect of Cd on SDW and Cd accumulation in plants grown on Cd-polluted soils, so the risk of Cd entrance to the food chain is reduced (however, in Cd-untreated soils, K-nano-chelate increased the Cd translocation factor higher than other K sources). In Cd-polluted soils KCl was the most inappropriate fertilizer that may intensify Cd accumulation in plants. However, it may be useful in the phytoremediation of Cd-polluted soils.

Regulation of 2,4-epibrassinolide on mineral nutrient uptake and ion distribution in Ca(NO3)2 stressed cucumber plants

2,4-Epibrassinolide (EBL) is a plant hormone that plays a pivotal role in regulation of plants growth and development processes under abiotic stress. The investigation was carried out to study the effect of EBL on mineral nutrients uptake and distribution with ion element analysis and X-ray microanalysis in cucumber seedlings (Cucumis sativus L. cv. Jinyou No.4) under 80mM Ca(NO3)2 stress. Our study found EBL significantly alleviated the inhibitory of P, K, Na, Mg, Fe, Mn, or Cl uptake in shoot or root by Ca(NO3)2 stress. Under Ca(NO3)2 stress, X-ray microanalysis showed that high levels of Ca by EBL treatment accumulated in the epidermal cells of root and gradually decreased from epidermal cells to stellar parenchyma. K+ levels were restored in different cross section of roots and high K+ level mostly accumulated in stellar parenchyma. The results of Ca2+ ultra-structural localization showed Ca2+ particles of antimonite precipitate by EBL were partly decreased in mesophyll and root cells, and Ca2+ precipitate distributed in intercellular spaces again. Increased Ca2+-ATPase activity and ATP content by EBL were also contributed to extrude excess Ca2+ from the cytoplasm. These results suggested that EBL could alleviate the ion damage from excess Ca2+ through regulating mineral nutrients uptake and distribution.

Uptake of cadmium by cress, lettuce and tomato in Cd-contaminated soil

Increasing of water consumption and demand for irrigation water in agriculture has led to an increase in reuse of treated, or even raw, municipal and industrial wastewater in many countries. Heavy metals (HMs) in these unconventional waters are one of the sources of pollution of water, soil and plant. HM toxicity in plants may eventually cause disturbances in plant growth. Accumulation of HMs in plants has health problems for human beings and animals which consume these plants. In this research, uptake of cadmium (Cd) by three vegetables (cress (Lepidium sativum L.), lettuce (Lactuca sativa L.) and tomato (Solanum lycopersicum L.) from a contaminated soil was studied. The experimental design was completely randomized. For each plant, two soil treatments (control soil and contaminated soil by 100 mg/L Cd) and five replications were considered. After planting, growing and harvesting, and preparation of the samples, Cd uptake in roots and shoots was measured. Results showed that mean Cd uptake by all three plants was significantly different from the control treatment. Maximum uptake of Cd belonged to tomato, whereas lettuce had the lowest uptake. Transfer coefficient of Cd from soil into cress, lettuce and tomato was 1.3, 0.33 and 0.65, respectively. Although transfer coefficient of Cd to lettuce is lower than the other two plants, but consumption of lettuce per person is much greater than cress. Hence, irrigation management of polluted wastewater is important.

Uptake, Translocation, and Metabolism of Phenols by Submerged Rooted Macrophyte, Water Milfoil (Myriophyllum elatinoides).

Shoot and root uptakes of (14)C-labeled phenol (1), 4-nitrophenol (2), 4-cyanophenol (3), 4-hydroxybenzamide (4), and 4-hydroxybenzoic acid (5) by Myriophyllum elatinoides were individually examined with water or sediment treatments using the sequestered chamber. Shoot uptake of each (14)C-phenol dissolved in water amounted to 21.0% (1), 14.3% (2), 12.8% (3), 4.2% (4) and 41.7% (5) of the applied radioactivity (AR) after 96 h without significant (14)C translocation from shoot to root (≤0.9% AR), and the major metabolite produced was the glucose conjugate. On the other hand, root uptake of (14)C-phenols from sediment was much slower/smaller (≤6.6% AR), and (14)C transportation from root to shoot was scarcely observed, except for compound 5 (≤1.5% AR). For the water treatment, a kinetic analysis on uptake/metabolism was conducted using the assumed compartment. Good correlation was observed between lipophilicity and shoot uptake rate constants, and the electronic state of the hydroxyl group (σ, σ(-), or EHOMO(OH)) and the transformation rate constant of glucosidation.

Potassium Fertilization Influences Growth, Physiology and Nutrients Uptake of Maize (Zea Mays L.)

Abstract A pot experiment in wire house was conducted to investigate the effect of potassium fertilization on physiology, growth and nutrient uptake of maize. Surface soil samples were collected and analyzed for soil physico-chemical properties and NPK contents. Pots were saturated with water and filled with soil (5 kg soil/pot). Potassium fertilizer was applied in five different treatments as T1, T2, T3, T4 and T5 with 0, 70, 100, 130, and 160 kg ha-1, respectively. Nitrogen and phosphorus were applied @ 250 and 100 kg ha-1 (recommended), respectively, in all the pots, including control. Experiment was planned in completely randomized design (CRD), with three repeats. Plant growth, nutrient uptake and concentration in roots and shoots, net photosynthesis, rate of transpiration, stomatal conductance and substomatal CO2 concentration were significantly improved with increasing K application rate. It also increased water use efficiency (WUE) and decreased root: shoot dry weight ratio of maize. Treatment T3 resulted in maximum growth, physiological characteristics and nutrient uptake. It was concluded that K fertilization improves physiological characteristics resulting in enhanced WUE and nutrient uptake eventually producing more yield. It is recommended to apply K fertilization in drought stress conditions.

Effects of Biofertilizers on Mn and Zn Acquisition and Growth of Higher Plants: A Rhizobox Experiment

Plant disease resistance and susceptibility are greatly influenced by the availability of micronutrients, particularly manganese (Mn) and zinc (Zn). Take-all disease of wheat, caused by a strong Mn oxidizing fungus (Gaeumannomyces graminis var tritici, Ggt), results in a lack of availability of Mn to plants and increases disease severity in wheat. Three commercial Trichoderma harzianum (Vitalin T-50, BioHealth®-WSG, and BioHealth®-G) and one Bacillus subtilis (Vitalin SP-11) were investigated individually and in combination (Vitalin T-50 and Vitalin SP-11) for growth promotion and Mn/Zn uptake of take-all infected wheat in a rhizobox experiment under greenhouse conditions. Inoculation with Trichoderma and Bacillus biofertilizers did not increase the shoot dry weight and shoot to root ratio, whilst shoot length was significantly increased with Vitalin T-50 and Biohealth-G treatments in the final harvest. Biofertilizers inoculation that significantly (P < 0.05) enhanced root surface area and root dry weight were Vitalin T-50, BioHelath-G and combination of Vitalin (T-50 + SP-11). The bulk soil pH was not influenced by biofertilizer inoculation, whereas rhizosphere and rhizoplane soil pH were significantly reduced (0.3 – 0.4 pH scale) in Vitalin (T-50 + SP-11) and BioHealth-G treatments and to a lesser extent by Vitalin T-50 inoculation. Manganese uptake in shoots of wheat exhibited no significant differences among the biofertilizer treatments. On the contrary, Zn uptake was significantly higher in Vitalin T-50, Vitalin (T-50 + SP-11), BioHealth-G, and BioHealth-WSG (47, 64, 44, and 45%, respectively) inoculated plants. Therefore, Vitalin T-50 and Biohealth-G showed better performance in improving plant growth and Zn uptake.

Effect of elevated CO2 concentration on photosynthetic characteristics of hyperaccumulator Sedum alfredii under cadmium stress.

The combined effects of elevated CO2 and cadmium (Cd) on photosynthetic rate, chlorophyll fluorescence and Cd accumulation in hyperaccumulator Sedum alfredii Hance were investigated to predict plant growth under Cd stress with rising atmospheric CO2 concentration. Both pot and hydroponic experiments were conducted and the plants were grown under ambient (350 µL L(-1)) or elevated (800 µL L(-1)) CO2 . Elevated CO2 significantly (P < 0.05) increased Pn (105%-149%), Pnmax (38.8%-63.0%) and AQY (20.0%-34.8%) of S. alfredii in all the Cd treatments, but reduced chlorophyll concentration, dark respiration and photorespiration. After 10 days growth in medium with 50 µM Cd under elevated CO2 , PSII activities were significantly enhanced (P < 0.05) with Pm, Fv/Fm, Φ(II) and qP increased by 66.1%, 7.5%, 19.5% and 16.4%, respectively, as compared with ambient-grown plants. Total Cd uptake in shoot of S. alfredii grown under elevated CO2 was increased by 44.1%-48.5%, which was positively correlated with the increase in Pn. These results indicate that elevated CO2 promoted the growth of S. alfredii due to increased photosynthetic carbon uptake rate and photosynthetic light-use efficiency, and showed great potential to improve the phytoextraction of Cd by S. alfredii.