Shoot Uptake Research Articles

Dry Matter Yield of Sunflower as Affected by EDTA and EDDS Application in Soil Remediation from Ibadan, Metropolis, Nigeria

Phytoremediation has been found to be cost effective in removing heavy metals (HM) from polluted soils. Enhanced phytoextraction with the use of chelating agents for solubility of metal in soils and their uptake in the aerial parts of plants had also been employed. Phytoextraction efficiency of plants will depend on the metal accumulated in the dry matter yield of plant. An attempt was made to study the influence of Ethylene diamine tetra acetic acid (EDTA) and ethylene diamine disuccinic acid (EDDS) on the growth and dry matter yield content of sunflower planted in heavy metal polluted soils in a greenhouse pot experiment. Total heavy metal contents of five metals (Cu, Cd, Cr, Pb and Zn) were determined by acid digestion with aqua regia solution. A greenhouse experiment was conducted to assess the phytoextraction potential of sunflower with EDDS and EDTA applied at seven weeks after planting. Treatments were laid out in a completely randomized design with four replicates. Data were collected on metal accumulation in root and shoot, Total metal uptake, shoot and root dry matter yield and analyzed using descriptive statistics and ANOVA at α0.05. Original Research Article Thomas and Omueti; IJPSS, 7(1): 67-79, 2015; Article no.IJPSS.2015.132 68 The result shows a significant increase in the overall accumulation of metals in the root and shoot of sunflower and dry matter yield with EDDS except for Zn. However, Zinc only recorded significant increase in shoot uptake at 3 mmol/kg EDDS. The application of EDDS at 3 and 9 mmol/kg did better in total uptake of Cu, Pb and Cd. Ethylene diamine disuccinic acid (EDDS) was more efficient than EDTA in mobilizing metal uptake in sunflower root and shoot and also in increasing total dry matter yield. Translocation factor of Cd, Pb and Cu were enhanced by the addition of EDDS than EDTA application.

Physiological and Biochemical Evaluation of Fe-Efficiency in Fe-Deficient Maize Genotypes

Iron (Fe) deficiency is prevalent particularly in calcareous soils of arid and semiarid regions. The present study aimed to investigate the response of eight local maize genotypes to Fe deficiency. In addition, a Fe- efficient (WF9) and a Fe-inefficient (ys1) indicator genotypes were used in this study. All genotypes were grown in growth chamber for 21 days in two levels of Fe, sufficient [+Fe (FNS) = 20 µM Fe EDTA] and deficient [-Fe (FNS) = 2 µM Fe EDTA] Fe supply. Shoots dry weight, Fe concentration and uptake in shoots, active iron concentration, peroxidase activity and cholorophyll content were determined and their validities as screening parameters were discussed. Generally, genotype (WF9) as the Fe efficient indicator and genotype (34) were the less affected by Fe-deficiency. Genotype (ys1) as the Fe inefficient indicator and genotype (62) were highly affected when grown in the nutrient solution with the deficient Fe supply. The present study emphasize that shoot dry weight, Fe uptake, active Fe content, chlorophyll content and peroxidase activity could be used for evaluating the present maize genotypes for Fe efficiency.

Effect of Different Strains of Arbuscular Mycorrhizal Fungi (AMF) on Macro and Micro Nutrient uptake in Micropropagated Chrysanthemum Plantlets

Effect of different Arbuscular Mycorrhizal Fungi (AMF) on uptake of macro and micronutri-ents by in vitro raised plantlets of chrysanthe-mum cv. Yellow Bangla has been studied. Four AMF strains namely, Acaulospora laevis, Acau-lospora scorbiculata, Glomus fasciculatum and mixed AMF strains (Nutrilink®) were used to screen the suitable AMF strain for micropropa-gated chrysanthemum plantlets. These plantlets showed maximum accumulation of N, P and Ca both in shoots and roots at 90 DAI. Maximum K and Mg accumulation was observed at 60 DAI with the same fungal strain. The predominant effect of mixed AMF (Nutrilink®) was also ob-served in uptake of Fe and Mn at 90 DAI in both shoot and root samples. However, maximum ac-cumulation of Zn was observed in shoots of Glo-mus fasciculatum inoculated plantlets. The ex-periments revealed significant increase of nutri-ent uptake in both shoot and roots in the plant-lets inoculated with mixed AMF strains (Nutrilink®) followed by Glomus fasciculatum inoculated microplants.

The phytotoxicity of ZnO nanoparticles on wheat varies with soil properties.

Zn is an essential element for plants yet some soils are Zn-deficient and/or have low Zn-bioavailability. This paper addresses the feasibility of using ZnO nanoparticles (NPs) as soil amendments to improve Zn levels in the plant. The effects of soil properties on phytotoxicity and Zn bioavailability from the NPs were studied by using an acidic and a calcareous alkaline soil. In the acid soil, the ZnO NPs caused dose-dependent phytotoxicity, observed as inhibition of elongation of roots of wheat, Triticum aestivum. Phytotoxicity was mitigated in the calcareous alkaline soil although uptake of Zn from the ZnO NPs occurred doubling the Zn level compared to control plants. This increase occurred with a low level of Zn in the soil solution as expected from the interactions of Zn with the soil components at the alkaline pH. Soluble Zn in the acid soil was 200-fold higher and shoot levels were tenfold higher than from the alkaline soil correlating with phytotoxicity. Mitigation of toxicity was not observed in plants grown in sand amended with a commercial preparation of humic acid: growth, shoot uptake and solubility of Zn from the NPs was not altered by the humic acid. Thus, variation in humic acid between soils may not be a major factor influencing plant responses to the NPs. These findings illustrate that formulations of ZnO NPs to be used as a soil amendment would need to be tuned to soil properties to avoid phytotoxicity yet provide increased Zn accumulations in the plant.

Influence of transgenic ath-miR399d tomato lines on microbial community and diversity in rhizosphere soil

Transgenic ath-miR399d tomatoes (Solanum lycopersicum L. cv Zhongshu No. 4) have enhanced phosphorus (P) uptake and accumulation in shoots, and have the potential to improve P-use efficiency in agricultural soils. However, the effects of transgenic ath-miR399d tomatoes on soil microbial community and diversity are poorly understood. Soil carbon source utilization patterns and phospholipid fatty acid (PLFA) profiles were evaluated after a 35-d cultivation of transgenic tomato lines C1 and C2 and wild-type tomato at 0, 150 and 300 mg phosphorus pentoxide (P2O5) kg−1 soil. Microbial diversity indices deduced from carbon source utilization patterns were significantly decreased after cultivating transgenic tomato lines compared to wild-type tomato. So were the average well color development (AWCD) for general carbon sources, carbohydrates and amino acids. The AWCD for general carbon sources was increased with P levels, while the microbial diversity indices did not differ significantly among three P levels. The amounts of total, bacterial and Gram-positive bacterial PLFA significantly declined after cultivating transgenic tomato lines. So were Gram-negative bacterial PLFA at 0 and 150 mg P2O5 kg−1 soil. In contrast, the numbers of individual PLFA, the PLFA ratio of fungi:bacteria and Gram-positive bacteria:Gram-negative bacteria were not significantly affected by genotype or P level after the 35-d cultivation of transgenic tomato lines. Principal component analysis (PCA) for both substrate utilization patterns and PLFA profiles showed good separation of soil microbial communities between the transgenic tomato lines and wild-type tomato. Our results suggest that transgenic ath-miR399d tomatoes have transient adverse effects on microbial community and diversity in rhizosphere soil.

Soil and Crop Micronutrient Concentrations as Modified by Wastewater Sludge

Soil extracts are used to provide a measure of plant nutrient bioavailability, but their predictive capacity is variable. In a greenhouse experiment, soil was amended with sewage sludge from textile manufacturing wastewater. We investigated the correspondence between maize ( Zea mays L.) shoot uptake and concentrations in soil extractions for plant essential micronutrients concentrated in the sludge: B, Cu, Mn, and Zn. Hot water extract was used for B, whereas diethylene triamine pentaacetic acid (DTPA) extract was used for Cu, Mn, and Zn. Separate pots with NH 4 NO 3 amendment, but no sludge, allowed comparison of soil micronutrient extraction and plant uptake under conditions of elevated mineral N fertility similar to those with sludge amendment, but in the absence of sludge. Addition of sludge did not change soil extractable concentrations nor shoot concentrations of B and Zn. B was abundant in the sludge but likely remained strongly bound as organic complexes, whereas the quantity of Zn was not high enough to register difference. Shoot Mn was increased by both sludge amendment and an NH 4 NO 3 effect, likely from pH decrease associated with nitrification of the ammonium in the sludge and in the fertilizer. DTPA-extractable Mn increased in sludge-amended plots. DTPA-extractable Cu increased strongly following sludge amendment, but, in contrast to Mn, shoot Cu concentration was not changed. Thus, selectivity of roots to avoid Cu is not revealed by DTPA. The correspondence between extraction-based estimation of availability and the actual plant uptake varies among micronutrients due to effects of soil conditions and selectivity of roots.

Nano-CuO and interaction with nano-ZnO or soil bacterium provide evidence for the interference of nanoparticles in metal nutrition of plants.

The expansion of nanotechnology raises concerns about the consequences of nanomaterials in plants. Here, the effects of nanoparticles (NPs; 100-500mg/kg) on processes related to micronutrient accumulation were evaluated in bean (Phaseolus vulgaris) exposed to CuO NPs, a mixture of CuO and ZnO (CuO:ZnO) NPs, and in CuO NP-exposed plants colonized by a root bacterium, Pseudomonas chlororaphis O6 (PcO6) in a sand matrix for 7days. Depending on exposure levels, the inhibition of growth by CuO NPs was more apparent in roots (10-66%) than shoots (9-25%). In contrast, CuO:ZnO NPs or root colonization with PcO6 partially mitigated growth inhibition. At 500mg/kg exposure, CuO NPs increased soluble Cu in the growth matrix by 23-fold, relative to the control, while CuO:ZnO NPs increased soluble Cu (26-fold), Zn (127-fold) and Ca (4.5-fold), but reduced levels of Fe (0.8-fold) and Mn (0.75-fold). Shoot accumulations of Cu (3.8-fold) and Na (1-fold) increased, while those of Fe (0.4-fold), Mn (0.2-fold), Zn (0.5-fold) and Ca (0.5-fold) were reduced with CuO NP (500mg/kg) exposure. CuO:ZnO NPs also increased shoot Cu, Zn and Na levels, while decreasing that of Fe, Mn, Ca and Mg. Root colonization reduced shoot uptake of Cu and Na, 15 and 24%, respectively. CuO NPs inhibited ferric reductase (up to 49%) but stimulated cupric (up to 273%) reductase activity; while CuO:ZnO NPs or root colonization by PcO6 altered levels of ferric, but not copper reductase activity, relative to CuO NPs. Cu ions at the level released from the NPs did not duplicate these effects. Our findings demonstrate that in addition to the apparent phytotoxic effects of NPs, NP exposure may also have subtle impacts on secondary processes such as metal nutrition.

Antioxidant enzymes and proteins of wetland plants: their relation to Pb tolerance and accumulation.

Constructed wetlands used to clean up toxic metals such as lead (Pb) from contaminated wastewater are considered as an effective and low-cost technology. The effect of Pb on the biomass, tolerance, soluble protein, and antioxidant enzymes in 18 candidate wetland plant species grown in soils without (control) and spiked with 900 and 1800 mg Pb kg(-1) was studied in a pot trial. Our pot experiment showed that the biomass, tolerance, and leaf protein contents decreased with increasing concentrations of Pb in soil. There were significant differences between the plants in their Pb tolerance indices (29-82 % in the 900 mg Pb kg(-1) amended soil) and also Pb uptake (13-749 mg kg(-1) in shoots and 1112-4891 mg kg(-1) in roots, in the same treatments). Activities of superoxide dismutase (SOD) and peroxidase (POD) in leaves of most of the plants increased with increasing level of soil Pb concentration. Conversely, catalase (CAT) activity in leaves declined when plants were subjected to Pb stress. Lead accumulation by the 18 wetland plant species screened was strongly dependent on the species and Pb concentrations in the soil. However, Pb translocation from root to shoot was generally low in all species. Increases in SOD and POD activities suggest that the antioxidant system may play an important role in alleviating Pb toxicity in wetland plants. The data obtained should help in future species selection for the use in designing wetlands in Pb-contaminated environments.

Cadmium accumulation and tolerance of two castor cultivars in relation to antioxidant systems

To investigate the effects of Cd on tolerance and antioxidant activities of castor, two different castor (Ricinus communis L.) cultivars (Zibo No. 5 and Zibo No. 8) were used for a hydroponic experiment (0, 1 and 2mg/L Cd) and a pot experiment using Cd-contaminated soil (34mg/kg) with the addition of ethylenedinitrilotetraacetic acid (EDTA). The results indicated that there were significant differences between the two cultivars with respect to Cd uptake in shoots (113–248mg/kg for Zibo No. 5 and 130–288mg/kg Zibo No. 8), biomass tolerance indexes (64.9%–74.6% for Zibo No. 5 and 80.1%–90.9% for Zibo No. 8) in the hydroponic experiment and survival rates (0% for Zibo No. 5 and 100% for Zibo No. 8) determined by the addition of EDTA in the pot experiment, suggesting that Zibo No. 8 has higher tolerance than Zibo No. 5. Moreover, the castor cultivars have low bioconcentration factors (4.80% for Zibo No. 5 and 5.43% for Zibo No. 8) and low translocation factors (<1%). Consequently, Zibo No. 8 can participate in Cd phytostabilization in highly Cd-polluted areas. The results indicated that glutathione (GSH) as a non-enzymatic antioxidant, and antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT) and guaiacol peroxidase (GPX), were cultivar- and dose-dependent. The higher tolerance of Zibo No. 8 compared with Zibo No. 5 can be attributed to the higher GSH levels in the root and higher GPX activity in the leaf.

Genetic and physiological analysis of tolerance to acute iron toxicity in rice.

BackgroundFe toxicity occurs in lowland rice production due to excess ferrous iron (Fe2+) formation in reduced soils. To contribute to the breeding for tolerance to Fe toxicity in rice, we determined quantitative trait loci (QTL) by screening two different bi-parental mapping populations under iron pulse stresses (1,000 mg L−1 = 17.9 mM Fe2+ for 5 days) in hydroponic solution, followed by experiments with selected lines to determine whether QTLs were associated with iron exclusion (i.e. root based mechanisms), or iron inclusion (i.e. shoot-based mechanisms).ResultsIn an IR29/Pokkali F8 recombinant inbred population, 7 QTLs were detected for leaf bronzing score on chromosome 1, 2, 4, 7 and 12, respectively, individually explaining 9.2-18.7% of the phenotypic variation. Two tolerant recombinant inbred lines carrying putative QTLs were selected for further experiments. Based on Fe uptake into the shoot, the dominant tolerance mechanism of the tolerant line FL510 was determined to be exclusion with its root architecture being conducive to air transport and thus the ability to oxidize Fe2+ in rhizosphere. In line FL483, the iron tolerance was related mainly to shoot-based mechanisms (tolerant inclusion mechanism). In a Nipponbare/Kasalath/Nipponbare backcross inbred population, 3 QTLs were mapped on chromosomes 1, 3 and 8, respectively. These QTLs explained 11.6-18.6% of the total phenotypic variation. The effect of QTLs on chromosome 1 and 3 were confirmed by using chromosome segment substitution lines (SL), carrying Kasalath introgressions in the genetic background on Nipponbare. The Fe uptake in shoots of substitution lines suggests that the effect of the QTL on chromosome 1 was associated with shoot tolerance while the QTL on chromosome 3 was associated with iron exclusion.ConclusionTolerance of certain genotypes were classified into shoot- and root- based mechanisms. Comparing our findings with previously reported QTLs for iron toxicity tolerance, we identified co-localization for some QTLs in both pluse and chronic stresses, especially on chromosome 1.

Effects of Salinity and Copper on Growth and Chemical Composition of Pistachio Seedlings

The effects of five salinity levels and four copper levels on growth and chemical composition of ‘Ghazvini, pistachio seedlings were studied under greenhouse conditions in a completely randomized design with three replications. Leaf area, stem height, shoot and root dry weights were determined on 24th week after planting. Copper (Cu), phosphorus (P), sodium (Na), and chlorine (Cl) total uptake in shoot and root of plant were measured. The results showed that salinity decreased growth parameters. Low levels of Cu application had no significant effect on leaf area, shoot and root dry weights while decreased stem height. The highest level of Cu (7.5 mg Cu kg−1 soil) significantly increased leaf area and shoot dry weight but decreased stem height. Salinity decreased Cu and P uptake in the shoot and root, but increased total sodium and chloride uptake. Cu application increased shoot total P uptake and decreased root total Na uptake.

Effects of Soil and Foliar Application of Boron on Nutrient Uptake, Growth, and Yields of Red Bayberry

The results of a three-year field experiment showed that boron application significantly increased spring shoot length, spring shoot incidence, leaf area, and uptake of N, P, and K in red bayberry (Myrica rubra Sieb. et Zuca). Soil application of boron gave a significantly higher fruit yield than foliar application of boron in 2009 and 2008. On average, over three years the increases in uptake amounts of N, P, and K as well as fruit yield were in the following order: soil application of boron every year > foliar B application every year > soil B application only in the first year > foliar B application only in the first year.

EFFECTS OF AMELIORANT COMPOSITIONS ON NITROGEN MINERALIZATION AND UPTAKE BY SWEET CORN IN DEGRADED PEATLAND

Peat soil is characterized by poor nitrogen (N) availability. Ameliorants are expected to rectify this problem. This research aimed to study the effect of ameliorant on N availability and N uptake by sweet corn plant in degraded peatland. The experiment was conducted in the greenhouse in May-July 2011 and on peatland of Kalampangan Village, Palangkaraya, Central Kalimantan in September-December 2011. Burnt peat soil of Kalampangan was used in the greenhouse experiment and sweet corn was used as an indicator plant. The treatments consisted of two factors, i.e. compositions of ameliorants by weight (A1 = 80% chicken manure + 20% dolomite; A2 = 80% local farm weed + 20% dolomite; A3 = 80% mineral soil + 20% dolomite; A4 = 20% chicken manure + 20% local farm weed + 20% residue of Chinese water chestnut (Eleocharis dulcis) + 20% mineral soil + 20% dolomite; and A5 = 19% chicken manure + 71.5% mineral soil + 9.5% dolomite) and rates of those ameliorants (5, 10, 15, 20 and 25 t ha-1). The experiment was arranged in a completely randomized block design with three replications. Data were collected every two weeks for five times. Observations were made on soil pH, available N (NH4+, NO3-), plant height, and N uptake in root and shoot. The results showed that treatment A1 increased soil pH and availability of NH4+ and NO3- in peat soils at the maximum vegetative stage. Treatment A1 provided the highest N availability and N uptake by the plant. Field experiment showed that N uptake increased with the plant yield. Optimum yield of fresh corn cob was obtained from treatment A1 at the rate of 20 t ha-1. This research reconfirms the effectiveness of chicken manure and dolomite as peat soil ameliorant.

EFFECTS OF AMELIORANT COMPOSITIONS ON NITROGEN MINERALIZATION AND UPTAKE BY SWEET CORN IN DEGRADED PEATLAND

Peat soil is characterized by poor nitrogen (N) availability. Ameliorants are expected to rectify this problem. This research aimed to study the effect of ameliorant on N availability and N uptake by sweet corn plant in degraded peatland. The experiment was conducted in the greenhouse in May-July 2011 and on peatland of Kalampangan Village, Palangkaraya, Central Kalimantan in September-December 2011. Burnt peat soil of Kalampangan was used in the greenhouse experiment and sweet corn was used as an indicator plant. The treatments consisted of two factors, i.e. compositions of ameliorants by weight (A1 = 80% chicken manure + 20% dolomite; A2 = 80% local farm weed + 20% dolomite; A3 = 80% mineral soil + 20% dolomite; A4 = 20% chicken manure + 20% local farm weed + 20% residue of Chinese water chestnut (Eleocharis dulcis) + 20% mineral soil + 20% dolomite; and A5 = 19% chicken manure + 71.5% mineral soil + 9.5% dolomite) and rates of those ameliorants (5, 10, 15, 20 and 25 t ha-1). The experiment was arranged in a completely randomized block design with three replications. Data were collected every two weeks for five times. Observations were made on soil pH, available N (NH4+, NO3-), plant height, and N uptake in root and shoot. The results showed that treatment A1 increased soil pH and availability of NH4+ and NO3- in peat soils at the maximum vegetative stage. Treatment A1 provided the highest N availability and N uptake by the plant. Field experiment showed that N uptake increased with the plant yield. Optimum yield of fresh corn cob was obtained from treatment A1 at the rate of 20 t ha-1. This research reconfirms the effectiveness of chicken manure and dolomite as peat soil ameliorant.

EFFECTS OF SALINITY AND CALCIUM ON THE GROWTH AND CHEMICAL COMPOSITION OF PISTACHIO SEEDLINGS

Poor quality of irrigation water (high salinity) has reduced the yields of pistachio over recent years, especially in Kerman. The effects of four salinity levels [0, 30, 60, and 90 mM sodium chloride (NaCl)] and three calcium (Ca) levels [0, 0.5, and 1 mM Ca as calcium nitrate (Ca(NO3)2.4H2O)] on growth and chemical composition of pistachio seedlings cv. ‘Badami’ were studied in sand culture under greenhouse conditions in completely randomized design (CRD) with four replications. After 170 days, leaf area, leaf number, shoot and root dry weights were determined. Also shoot and root sodium (Na), potassium (K), Ca, and magnesium (Mg) concentrations were measured. Results showed salinity decreased all growth parameters. Ca application increased shoot and root Ca concentrations and root K concentration, while Ca application decreased shoot K concentration and shoot and root Mg concentrations. Salinity decreased shoot Ca, root K, and root Mg concentrations, while salinity increased shoot and root total sodium uptake, and shoot and root Cl concentrations.

Chromium phytoextraction from tannery effluent-contaminated soil by Crotalaria juncea infested with Pseudomonas fluorescens

The aim of present study was to remediate chromium (Cr)-contaminated soil by Crotalaria juncea in the presence of Pseudomonas fluorescens. Inoculation of P. fluorescens in pot soil grown with C. juncea significantly increased (~2-fold) the water-soluble (Ws) and exchangeable (Ex) Cr contents in contaminated soil under greenhouse condition. It also enhanced the chlorophyll content by 92 % and plant biomass by 99 % as compared to the uninoculated C. juncea plant. The analysis showed that root and shoot uptake of Cr in C. juncea inoculated by P. fluorescens was 3.08- and 2.82-fold, respectively. This research showed that the association of C. juncea and P. fluorescens could be a promising technology for increasing the soil Cr bioavailability and plant growth for successful phytoextraction of Cr from the contaminated soil.

White clover living mulch controlled only by mowing supplies nitrogen to corn

A field experiment was conducted to investigate the effects of white clover (Trifolium repens L.) living mulch controlled only by mowing on the nitrogen (N) nutrition and yield of silage corn (Zea mays L.). Eight treatments were tested: one living mulch treatment without N application and seven conventional cultivation treatments with different N applications (0–200 kg ha−1). White clover was sown in the living mulch treatment in August. The next May, white clover shoots in the living mulch treatment were clipped and left in the field. After tilling the conventional cultivation treatments, corn was sown. At the time when the corn was sown, the N uptake of the white clover shoots was 173 kg ha−1. Measurements at 40 days after the sowing of corn (40 DAS) revealed that the N concentration of corn shoots grown in the living mulch treatment was lower than that in the conventional cultivation treatment without N application. At harvest (123 DAS), compared with that in the conventional cultivation treatment without N application, the N uptake of corn shoots in the living mulch treatment increased by 31.8 kg ha−1. Based on the N uptake and the yield of corn, the fertilizer N equivalencies of living mulch were 62 and 70 kg ha−1 at harvest, respectively. These results indicate that living mulch controlled only by mowing increases the N uptake of corn and may reduce the N application required for corn production.

Interactive Effect of Soil Salinity and Copper Application on Growth and Chemical Composition of Pistachio Seedlings (cv. Badami)

The effects of five salinity levels and four Cu levels on growth and chemical composition of Badami pistachio seedlings were studied under greenhouse conditions in a completely randomized design with three replications. Growth parameters were determined on the 24th week after planting. Total elemental uptake amounts in shoot and root of plant were measured. Results showed that salinity decreased leaf area, stem height, and shoot and root dry weights. Application of 2.5 and 5 mg copper (Cu) kg−1 soil significantly increased root dry weight, whereas it had no significant effects on shoot dry weight and leaf area. Application of 7.5 mg Cu kg−1 soil had a negative effect on stem height. Salinity declined shoot and root total Cu and phosphorus (P) uptake amounts but increased shoot and root total sodium (Na) and chlorine (Cl) uptake amounts. Copper increased shoot and root total Cu uptake amounts, root total P uptake, and shoot total Na uptake but decreased shoot total Cl uptake.

Effects of plant growth-promoting rhizobacterium (PGPR) and arbuscular mycorrhizal fungus (AMF) on antioxidant enzyme activities in salt-stressed bean (phaseolus vulgaris l.)

Abstract Plant Growth-Promoting Rhizobacterium (PGPR) represents a wide variety of soil bacteria that, when grown in association with a host plant, result in stimulation of growth of their host. The aim of this study was to investigate the influence of inoculation with a PGPR, Pseudomonas fluorescence, alone or in combination with an arbuscular mycorrhizal fungus, Glomus mosseae (Nicol. &amp; Gerd.), on antioxidant enzyme activities (catalase (CAT) and peroxidase (POX)), phosphatase activity, solutes accumulation, growth and minerals nutrient uptake in shoots of bean (Phaseolus vulgaris L.) affected by three levels of salt stress. Salinity decreased bean growth, regardless of the biological treatment and the salt stress level. The plants inoculated with P. fluorescence had significantly greater shoot biomass than the control plants at all salinity levels, whereas the mycorrhizal inoculation treatments were only effective in increasing shoot biomass at a low salinity level. The plants inoculated with P. fluorescence presented higher concentrations of shoots’ K+ and lower concentrations of shoots’ Na+ under high salt conditions. Salt stress increased shoots’ proline concentration, particularly in plants inoculated with the PGPR. Increasing salinity stress raised significantly the antioxidant enzyme activities, including those of total POX and CAT, of bean shoots compared with their corresponding nonstressed plants. The PGPR strain induced a higher increase in these antioxidant enzymes in response to severe salinity. Inoculation with selected PGPR could serve as a useful tool for alleviating salinity stress in salt-sensitive plants.

Nitrogen Uptake and Use Efficiency in Upland Rice under Two Nitrogen Sources

Upland rice is an important crop in South America, including Brazil. Nitrogen (N) is one of the most yield-limiting nutrients in upland rice production in Brazil. A greenhouse experiment was conducted to evaluate N uptake and use efficiency as influenced by N sources. The soil used in the experiment was an Oxisol. The N sources were ammonium sulfate and urea, and N rates were 0, 50, 100, 150, 300, and 400 mg kg−1 of soil. Nitrogen concentrations in the root, shoot, and grain were significantly influenced by N sources. The N rate and N source significantly influenced the N uptake in root, shoot, and grain. Similarly, nitrogen rate by N source interaction was also significant for N uptake in the root, shoot, and grain, indicating N source has a significant influence on uptake of N. Overall, concentration (content per unit dry weight) of N was greater in the grain, followed by root and shoot. Agronomical efficiency, apparent recovery efficiency, and utilization efficiency of N were significantly influenced by N rate and varied with N sources. However, physiological and agrophysiological efficiencies were only influenced significantly by N sources. Overall, N recovery efficiency was 33% for ammonium sulfate and 37% for urea. Hence, the large amount of N lost from soil–plant system may be by denitrification or voltilization.