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Phytoremediation is a promising cleanup technology for contaminated soils, groundwater, and wastewater that is both low-tech and low-cost. The objective of this study was to investigate the ameliorative effect of phytoremediation on municipal wastewater (MWW). For this purpose, a phytoremediation garden was established using different aquatic plants species [Pistia stratiotes,Eichhornia crassipess,Hydrocotyle umbellatta,Lemna minor,Tyhpa latifolia, andScirpus acutus] in seven earthen pond systems (P1-P7) for the cyclic treatment of MWW. The physico-chemical analysis of MWW was carried out before and after the cyclic phytoremediation. Results showed that pH, EC and turbidity of MWW were reduced by 5.5%, 33.7%, and 93.1%, respectively after treatment (from P1 to P7). Treatment system also reduced total dissolved solids (TDS) by 35.2%, Cl by 61%, HCO3by 29.2%, hardness by 45.7%, Ca by 32.3% and Mg by 55.9%. Nitrate concentration was reduced by 77.6% but SO4was enhanced slightly. An ameliorative combined effect of wetland plants namelyL. minor,T. latifolia, andS. acutuson MWW was noticed. Sequential phytoremediation with a mixture of plants was more effective than that relying only on a single plant species. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effect of silicon (Si) on soybean seedlings under (combined) drought and ultraviolet-B (UV-B) radiation stresses. Specifically, we determined dry matter accumulation and partitioning of the mineral elements in different organs of soybean seedlings using the inductively coupled plasma mass spectrometry (ICP-MS). The amount of dry matter accumulated in root, stem, and leaf of seedlings treated with (combined) drought and UV-B radiation stresses were lower than that of the control. Also, the content of macroelements in seedlings under the combined stress was lower than in those under control conditions. Changes in the contents of microelements varied according to the intensity of drought, UV-B radiation, and the organs of soybean. The relationship between the contents of mineral elements and the accumulation of dry matter also varied similarly. These results demonstrated that drought and UV-B radiation induced an alteration in the distribution of mineral elements in root, stem and leaf, leading to decreases in dry matter accumulation and inhibition of soybean growth. [ABSTRACT FROM PUBLISHER]

The aim of this study was to investigate the potential of silicon (Si) for alleviating Ultraviolet-B (UV-B) radiation stress based on changes in biomass, physiological attributes and photosynthetic characteristics of two soybean (Glycine maxL.) cultivars, Kenjiandou 43 (‘K 43’) and Zhonghuang 35 (‘ZH 35’). The cultivars were raised with and without Si in the greenhouse, and then subjected to ambient, ambient + 2.7 kJ m−2d−1and ambient + 5.4 kJ m−2d−1of UV-B radiation. Depending on cultivar, plants suffered severe growth limitations under UV-B radiation, but the application of Si alleviated the adverse effects on growth and development by increasing the stem length, net photosynthetic rate (PN) and leaf chlorophyll content. Concurrently, it decreased the stomatal conductance (Sc) and intercellular carbon dioxide (CO2) concentration (Ci). In response to the UV-B radiation stress, the antioxidant enzyme activities of superoxide dismutase (SOD) increased by 41.2–72.7%, peroxidases (POD) by 49.5–85.7%, malodialdehyde (MDA) by 6.7–20.4% and soluble protein by 4.2–7.6%. The overall results indicated that media treatment with Si might improve soybean growth under elevated UV-B radiation through positive changes in biomass and some physiological attributes that were dependent on cultivar. [ABSTRACT FROM PUBLISHER]

The present study aimed to assess the concentrations of phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) in poultry litter (PL) and poultry litter ash (PLA) using eight chemical solutions (acids, chelating agents, salts solution and water). The relationship of maize (Zea maysL.) growth to the P extractability by these extractants was determined. For this purpose, PL was ashed at 600°C. Both PL and PLA were applied to two types of soils at the rate of 100, 200 and 300 kg P ha−1. Poultry litter, PLA and amended soils were analyzed for extractable P, K, Ca, and Mg using 1Mnitric acid (HNO3), 0.1MHNO3, 0.01MHNO3, ethylenediaminetetraacetate (EDTA), ammonium nitrate (NH4NO3), ammonium acetate (NH4OAc), calcium chloride (CaCl2) and deionized H2O extractions. For both PL and PLA, nutrients were varied in the order of P > Ca > K > Mg. Except water, all extractions released higher P in PLA than PL. The extractable nutrients seemed to have positive correlations with the application rate. Ashing of PL released higher concentrations of K, Ca, and Mg among all extractants. The extraction methods for P release differed in the order of 1MHNO3> 0.1MHNO3≈ EDTA > 0.01MHNO3> NH4NO3≈ NH4OAc > CaCl2> H2O in PL and PLA amended soils. Soils amended with PLA produced higher maize biomass than PL treated soils. Plant growth increased under increasing applications of PL and PLA. Plants under PLA treatments exhibited higher concentration of nutrients. Phosphorus availability was highly correlated to P uptake and plant biomass. [ABSTRACT FROM PUBLISHER]

Genotypic differences in potassium (K) uptake and utilization were compared for eight cotton cultivars in growth chamber and field experiments. Four of the cultivars ('SGK3', 'SCRC18', 'SCRC21' and 'SCRC22') typically produce lower dry mass and the other four ('Nannong8', 'Xiangza2', 'Xinluzao12' and 'Xiangza3') produce greater dry mass in K-deficient solution (0.02 mM). The mean dry weight of seedlings (five-leaf stage) of cultivars with greater biomass was 155% higher than that of cultivars with lower biomass yield under K deficiency. However, all the genotypes had similar dry matter yields in K-sufficient solution (2.5 mM). Thus, the four cultivars with superior biomass yield under low K medium may be described as K efficient cultivars while the inferior cultivars may be described as K inefficient. Although seeds of the studied cultivars originated from different research institutes or seed companies, there were little differences in seed K content among them, irrespective of their K efficiency. Consequently, there were no significant differences in K accumulation in seedlings (4 d after germination in a K-free sand medium) just before transferring to nutrient solutions. However, the K efficient genotypes, on average, accumulated twice as much K at 21 d after transferring to K-deficient solution (0.02 mM). A much larger root system as well as a slightly higher uptake rate (K uptake per unit of root dry weight) may have contributed to the higher net K uptake by the K efficient cultivars. In addition, the K efficiency ratio (dry mass produced per unit of K accumulated) and K utilization efficiency (dry mass produced per unit of K concentration) of the K efficient cultivars exceeded those of the K inefficient genotypes by 29% and 234%, respectively, under K deficiency. On average, the K efficient cultivars produced 59% more potential economic yield (dry weight of all reproductive organs) under field conditions even with available soil K at obviously deficient level (60 mg kg-1). We noted especially that the four K inefficient cultivars studied were all transgenic insect-resistant cotton, suggesting that the introduction of foreign genes (Bt and CpTI) may affect the K use efficiency of cotton. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine if treatment with silicon (Si) may improve nutrient uptake by soybean under ultraviolet-B (UV-B) radiation stress. Soybean (Glycine max L.) cultivars, 'Kennong 18' (K 18) and 'Zhonghuang 13' (ZH 13), were grown in hydroponic cultures under ambient and supplemental levels of ultraviolet-B (UV-B, 280-315 nm) with and without Si. Supplemental UV-B radiation simulating 30% stratospheric ozone depletion significantly decreased plant biomass by 74.9 to 135.6%, increased leaf nitrogen (N) and phosphorus (P) by 9% and 16%, respectively, decreased leaf magnesium (Mg) contents by 9%, and calcium (Ca) by 24%. UV-B radiation caused a substantial increase in the allocation of P, potassium (K) and Ca to roots compared with stem and leaves, presumably to ensure sustained nutrient uptake under the stress. Silicon application improved the uptake of P and Mg by 11%, which favored the partitioning of dry mass to shoots under UV-B radiation and the allocation of tissue P and Ca to roots. The overall changes due to Si supported a reasonable increase in dry mass of the 'K 18' cultivar. [ABSTRACT FROM AUTHOR]

Recycling combusted poultry litter ash as a soil amendment would potentially ameliorate problems normally associated with poultry waste management. We evaluated the effect of chicken litter ash (CLA) and duck litter ash (DLA) as nutrient sources for Japanese mustard spinach (Brassica rapa L. var. perviridis) grown on a sand dune soil. Chicken and duck litter were ashed at five temperatures: 200, 400, 600, 800, and 900°C and the resulting ash samples were applied at the rate of 100 kg phosphorus (P) ha-1. Laboratory analysis showed the highest P extraction with citric acid from CLA and DLA obtained at 600°C. Chicken litter ash was richer in P and potassium (K) than DLA but the later contained more calcium (Ca) and magnesium (Mg). The amount of ammonium acetate soluble calcium (Ca), magnesium (Mg), and K recovered increased with increasing temperature except for Ca and Mg at the highest temperatures, 800 and 900°C. Plants grown in pots with the CLA and DLA obtained at 400°C had the highest P concentration, yielding significantly more biomass with dense green leaf color but on average, the DLA amended soil had greater biomass. However, the P level was higher in CLA treated plants than DLA due to the higher available P level (citric acid soluble). Increases in electrical conductivity and pH of the soil were noted after harvest due to litter ash application. Our experiment demonstrated that poultry litter is potential source of P and other nutrients for horticutural crops. [ABSTRACT FROM AUTHOR]

Saline irrigation water has a tremendous impact on the yield potential of crops. Distribution of mineral elements in the parts of maize plant in response to saline water and nitrogen (N) nutrition was studied in a pot experiment for six weeks. Plants were irrigated either with tap water or saline water (ECw: 3.2 dSm-1). Nitrogen was applied at the rate of 0, 50, 100 and 200-kg ha-1 denoted as N0, N1, N2, and N3, respectively. Plants were separated into leaf, stem and root and analyzed for N, calcium (Ca), magnesium (Mg), sodium (Na), and potassium (K) concentrations. Dry matter production of leaf, stem and root was significantly reduced with saline water. The partitioning of elements in plants was the function of nitrogen and saline water. The N concentration of plant parts varied in the order of leaf > stem > root. A significant decrease in the N content was noted in plants under saline water. The root contained the highest Na content, Ca and Mg were higher in the leaf, whereas K was highest in the stem under saline water. Sodium was highest in the root and the remainder elements were greatest in the stem under tap water. Potassium and Cl were significantly reduced by N level whereas the reverse was true for Ca, Mg and Na content. The Na/K, Na/Ca, and Na/Mg ratios were also higher in salt stressed plant parts due to higher accumulation of Na ion. Among N-fertilizer treatments the Na/Ca and Na/Mg ratios were highest in control whereas Na/K increased with the addition of N. This study indicated that interaction of saline water and nitrogen has mixed effects on the partitioning of mineral elements in maize. [ABSTRACT FROM AUTHOR]

The effects of defoliation on soybean [Glycine max (L.) Merr.] growth and yield have been well studied, but relatively little is known about its nitrogen (N) accumulation after defoliation. An experiment was conducted to examine soybean recovery and N accumulation following defoliation. The indeterminate cultivar ('Tousan 69') was planted in a greenhouse, and two defoliation treatments (no defoliation and 67% defoliation) were imposed at the R2 stage when plants had at least one flower in the two uppermost nodes. At 0, 15, 30 and 45 days after defoliation (DAD), plants were destructively sampled to measure dry mass production, nitrogen accumulation and nitrogen fixation. Seed yield and N concentration also were measured at maturity. Neither the seed yield nor its N concentration was affected by defoliation. Although defoliation temporarily reduced soybean dry weight and N accumulation during 15 DAD, defoliated plants completely recovered their dry weight and N accumulation 30 DAD. There was little difference in N concentration between defoliated and non defoliated plants, indicating that N acquisition was restored during the recovery process. Recovery of N accumulation in defoliated plant was due to complete recovery of N2-fixing ability and maybe related to improvement in N absorption after defoliation. [ABSTRACT FROM AUTHOR]

Soil salinity is a major abiotic factor limiting crop production but an amendment with synthetic zeolite may mitigate effects of salinity stress on plants. The objective of the study was to determine the effects of zeolite on soil properties and growth of barley irrigated with diluted seawater. Barley was raised on a sand dune soil treated with calcium type zeolite at the rate of 1 and 5% and irrigated every alternate day with seawater diluted to electrical conductivity (EC) levels of 3 and 16 dS m-1. Irrigation with 16 dS m-1 saline water significantly suppressed plant height by 25%, leaf area by 44% and dry weight by 60%. However, a substantial increase in plant biomass of salt stressed barley was observed in zeolite-amended treatments. The application of zeolite also enhanced water and salt holding capacity of soil. Post-harvest soil analysis showed high concentrations of calcium (Ca2 +), magnesium (Mg2 +), sodium (Na+), and potassium (K+) due to saline water especially in the upper soil layer but concentrations were lower in soils treated with zeolite. Zeolite application at 5% increased Ca2 + concentration in salt stressed plants; concentrations of trace elements were also increased by 19% for iron (Fe2 +) and 10% for manganese (Mn2 +). The overall results indicated that soil amendment with zeolite could effectively ameliorate salinity stress and improve nutrient balance in a sandy soil. [ABSTRACT FROM AUTHOR]

Field water stress is a common problem in crop production, especially in arid and semi-arid zones and it is widely hypothesized that silicon (Si) could reduce water stress in plants. We set up a greenhouse study to evaluate some silicon sources - potassium silicate (K2SiO3), calcium silicate (CaSiO3) and silica gel for growth and nutrient uptake by four grass species under adequate and deficit irrigation. The four species studied were Rhodes grass (Chloris gayana), Timothy grass (Phleum pratense), Sudan grass (Sorghum sudanense) and Tall fescue (Festuca arundinacea). For all species, the biomass yield response to applied silicon under deficit irrigation was significantly better than under adequate irrigation. The yield response of Rhodes grass across silicon sources was 205% under deficit irrigation compared with only 59% under adequate irrigation; for Sudan grass it was 49% compared with 26% and for Timothy, it was 48% compared with a mere 1%. The higher responses under deficit irrigation suggest that the plants relied more on silicon to endure drought stress. Biomass yield of individual plants also differed according to soil water levels with Timothy grass being the most sensitive to water stress as it exhibited the highest yield response (209%) to adequate irrigation. This was followed by tall fescue (122%) and Rhodes grass (97%). Sudan grass was the least affected by deficit irrigation, possibly on account of improved root mass and its natural drought tolerance. Strong associations were noted between the uptake of silicon and those of nitrogen (N) and phosphorus (P) irrespective of soil water condition, but the uptake of potassium (K) was more strongly correlated with that of Si under deficit than adequate irrigation. Improvements in plant growth following Si application could therefore be linked to enhanced uptake of major essential nutrients. [ABSTRACT FROM AUTHOR]

An experiment was conducted to determine if salinity stress alters the response and tolerance of soybean to defoliation. Four soybean [ Glycine max (L.) Merr.] cultivars (‘Tachiutaka,’ ‘Tousan 69,’ ‘Dare’ and ‘Enrei’) in a growth chamber were exposed to two salinity treatments (0 and 40 mM NaCl) and two defoliation treatments (with and without defoliation). The interactive effects of salinity stress and defoliation on growth rate, leaf expansion, photosynthetic gas exchange, and sodium (Na + ) accumulation were determined. The decrease in growth rate resulting from defoliation was more pronounced in plants grown under salinity stress than in those grown without the stress. Without salinity stress, defoliated plants of all four cultivars had leaf-expansion similar rates to those of the undefoliated ones, but the photosynthetic rates of their remaining leaves were higher than those of undefoliated plants. However, with salinity stress, defoliated ‘Tachiutaka’ and ‘Tousa 69’ had lower leaf expansion and photosynthetic rates than undefoliated plants. For cultivars ‘Dare’ and ‘Enrei,’ the defoliated plants had leaf-expansion rates similar to undefoliated ones, but the photosynthetic rate of the remaining leaves did not increase. Except for cultivar ‘Dare,’ defoliated plants grown under salinity stress had higher Na + accumulation in leaves than undefoliated ones, and this result may be related to slow leaf expansion and photosynthesis. Salinity stress negatively affects soybean response and tolerance of defoliation, and the effects varied according to the salt tolerance of the cultivar. [ABSTRACT FROM AUTHOR]

Conserving irrigation water resources is a most important measure for sustainable wheat production in the North China Plain. In the present study, the effect of phosphorus (P) application for saving irrigation water was evaluated. The application of fertilizer P increased nitrogen and phosphorus uptake, shoot biomass, head number, seed number and, consequently, grain yield, and increased soil water use and seasonal evapo-transpiration. The lower the volume of irrigation water applied, the more obvious were these effects. When winter wheat was basally fertilized with 88.5 kg P 2 O 5 /ha and irrigated with 90 mm at the jointing stage, the highest fertilizer P use efficiency, apparent P recovery and net profit (due to irrigation and/or fertilizer P) were obtained. The results suggested that fertilizer P should be used for saving irrigation water resources in the North China Plain. [ABSTRACT FROM AUTHOR]

An environmentally controlled experiment was conducted in growth chambers to investigate the interactive effects of salinity and air humidity on two cultivars of tomato (Lycopersicon esculentum Mill.), Daniela (relatively salt tolerant) and Naomi (relatively salt sensitive). One month after germination, the plants were exposed for 15 days to factorial combinations of two salinity levels, 0 (control) and 80 mM sodium chloride (NaCl), and two relative humidity (RH) levels, 30% and 70%. The NaCl treatment decreased the growth of cv. Naomi by 34% and 21% at 30% and 70% RH, respectively, while there was no decrease in the growth of cv. Daniela at 30% RH and only a slight decrease at 70% RH. Under NaCl treatment, cv Daniela had significantly lower Na+concentrations in leaves and stems and a higher root-to-shoot ratio than cv. Naomi at both relative humidities. Salt tolerance of cv. Daniela may be related to its high root-to-shoot ratio and its ability to exclude Na+from the shoot. NaCl-treated plants of cv. Daniela had a lower biomass at 70% than at 30% RH. Conversely, NaCl-treated plants of cv. Naomi had a greater biomass at 70% compared with 30% RH. The ameliorating effects of high RH on NaCl-induced growth reductions in cv. Naomi could be attributed to an increase in leaf area, root growth, photosynthetic rate, and stomatal conductance and a decrease in Cl- concentration in leaves. The overall findings of this study suggest that the growth of salt-sensitive tomato cultivars under saline conditions could be improved by increasing air humidity. [ABSTRACT FROM AUTHOR]

Animal manures contain significant amounts of plant-available nutrients which could increase crop yields. They also contain heavy metals which may be exported outside soil systems by plants, animal and surface and underground water following application to soils. The effect of some animal manures on rice yield and extractability of iron (Fe), zinc (Zn), manganese (Mn), and copper (Cu) were determined in fours soils with different properties. The manures were applied at the rate of 100Mg ha-1, and rice was grown for two consecutive seasons. In the second of the two seasons, rice yield and yield components were determined. Immediately after the second season rice harvest, soils were sampled and analyzed for DTPA extractable Fe, Zn, Mn, and Cu. Averaged across the soils, the level of extractable Fe increased by between 5% in chicken manure (PM) and 71% in cattle manure (CM); Zn by between 312% in CM and 871% in swine manure (SM); Mn by between 61% in PM and 172% in SM and Cu by between 327% in PM and 978% in SM. Mixing these manures before application reduced the level of extractable trace elements. Although there was increased yield following application, the results of this study indicated a possible risk of trace element export to the environment within a year, if high levels of the manures are applied. [ABSTRACT FROM AUTHOR]

One of the measures being adopted for relieving environmental problems arising from agricultural production is to recycle animal manure and other organic products as fertilizers and soil amendment. In Japan, this is a usual practice among farmers. In this study, we evaluated the effects of chicken manure (PM), cattle manure (CM), swine manure (SM) and mixed manure (MM = PM + CM + SM) on the growth, dry matter yield, and nutrient [nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg)] uptake of rice (Oryza sativa Var. koshihikari). Four naturally infertile soils, andosol (A), red-yellow soil (RY), sandune soil (SD), and masatsuchi (M), were amended with 100 Mg ha-1 (dry weight) of each of the manure and allowed to stabilize for 4 weeks before rice was seeded. Changes in rice growth as indicated by plant height and number of leaves and tillers were monitored for 6 weeks, and the biomass yield was determined. Shoot samples were also analyzed for nutrient uptake. The amended A and RY soils produced the best effects on all the rice parameters studied. However, the number of rice leaves were significantly higher in RY than A. The manure effects on rice growth and biomass yield were ranked as CM > MM > SM > PM. Amending the soils with manure significantly delayed seedling emergence. Andosol amended with CM and MM produced significantly greater roots than with other manures. Masatsuchi amended with PM had lower shoot and root biomass than even the control. Among the manures, the uptake of all nutrients was highest in CM. The higher dry matter yield of rice in soils amended with CM and MM may be due to better nutrient balance and relatively lower levels of toxic factors in the material. [ABSTRACT FROM AUTHOR]