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Irrigation of plants by contaminated water with metals is very common in countries facing freshwater scarcity. To enhance plant growth via improved absorption of essential metals including Zn from wastewater the magnetization of water as a modern approach, can be used. With the aim of investigating the effects of brown coal application and magnetizing contaminated water on the absorption of Zn and the yield of maize, a greenhouse experiment was conducted. The experiment was factorial arranged in a completely randomized design with four levels of brown coal (0, 1, 2, and 4% w/w), and 5 types of irrigation water (distilled water, water contaminated with Cu-sulfate, water contaminated with Cu-nitrate, magnetized water contaminated with Cu-sulfate, and magnetized water contaminated with Cu-nitrate). Maize was irrigated according to the treatments of irrigation types, so that the total concentration of Zn added to the pots receiving Zn-contaminated water reached 1200 mg kg−1 at the end of experiment. Results showed that plants irrigated with Zn contaminated water significantly increased shoot dry matter yield, as compared to that of control treatment, due to high buffering capacity of the studied calcareous soil for stabilization of Zn. Magnetized water significantly increased mean shoot and root Zn uptake, uptake efficiency, phytoextraction efficiency, translocation factor, and translocation efficiency. Due to the improvement of Zn uptake by maize following the use of magnetized water, it is tentatively concluded that magnetization of waters with high level of Zn may be used for correcting Zn deficiency in calcareous soils. [ABSTRACT FROM AUTHOR]

Although crude oil contamination is a constraint for crop production, some plants can develop under crude oil contaminated conditions by utilizing crude oil as nutrients after decomposition. A greenhouse trial was conducted to investigate growth, nutritional composition and enzymatic response of vetiver grass in confronting with crude-oil contamination as affected by gibberellic acid (GA) and Tween 80. Application of GA or co-application of GA with Tween 80 significantly increased mean shoot dry weight. Application of Twee 80 alone or in combination with GA significantly increased mean root dry weight as compared to control which was attributed to the effectiveness of Tween 80 alone or in combination with GA on the removal of total petroleum hydrocarbons from polluted soil. Application of crude oil diminished shoot phosphorus, iron, zinc and manganese uptakes. Application of GA and Tween 80, however, compensated the decrease in nutrient uptakes in vetiver grass resulted from crude-oil contamination. Application of crude oil at both 2 and 4% (W/W) levels increased catalase (CAT) activity and proline (PRO) content. Superoxide dismutase (SOD) activity increased only following the application of 2% crude oil level, while addition of all amendments decreased CAT activity. Addition of GA decreased activity of SOD. None of the studied amendments had a significant effect on PRO content. Application of a combination of GA and Tween 80 under crude oil contamination are recommendable since such treatments not only inhibited adverse effect of crude oil on nutrients uptake but also caused that vetiver grass tolerated high level of crude oil contamination. [ABSTRACT FROM AUTHOR]

In order to study the effect of plant growth promoting rhizobacteria (PGPR), vermicompost and phosphate sources on the growth and nutrients uptake by lettuce, a greenhouse experiments was conducted. Treatments consisted of PGPR (Pseudomonas fluorescens) (with and without inoculation), vermicompost (0 and 1% w/w) and phosphate sources (control, rock phosphate (RP), tricalcium phosphate and triple super phosphate (TSP) at 25 mg P kg−1 level). Biological fertilizers, RP and TSP significantly increased shoot dry matter (SDM) and some measured nutrients uptake. Co-application of PGPR and RP, in non-vermicompost treatments significantly increased SDM, shoot nitrogen, phosphorus (P), potassium, zinc and manganese uptake rates. Shoot P uptake had no significant difference between TSP and RP treatments. Co-application of PGPR, vermicompost and TSP significantly decreased SDM, which may be due to the P toxic levels in the plant aerial parts and/or the inhibition of the bacterial activities in the rhizosphere soil. [ABSTRACT FROM AUTHOR]

Iron (Fe)-deficiency chlorosis is a common constraint when soybean (Glycine max L.) is grown on calcareous soils. Considerable differences exist among soybean genotypes for susceptibility to Fe chlorosis. In order to evaluate the effectiveness of iron-ethylenediamine di-o-hydroxyphenylacetic acid (Fe-EDDHA) for three soybean genotypes (A3237, Black hack, and Wells), field studies were conducted for the years 2001 and 2002 in a calcareous soil. Although, available Fe of the studied soils was either lower than critical level or in marginal range, application of Fe-EDDHA did not result in a significant increase in soybean yield probably, due to the antagonistic relationships between Fe and manganese (Mn). It appears that Fe soil test as the only criterion for Fe fertilizers recommendation is not appropriate and soil test for Mn is also recommended. Significant quadratic equations were obtained between chlorophyll meter readings (CMR) in growth stage 3 (GS3) with seed yield (SY) of A3237 and Black hack. However, SY of Wells showed close relationships with CMR in growth stage 4 (GS4). A tentative conclusion is that the chlorophyll meter is a reliable and non-destructive tool for the prediction of SY for the studied soybean genotypes in GS3 or GS4. Due to the fact that use of Fe fertilizer might cause nutritional disorder, use of Fe-efficient genotypes remains as an effective and economic sound practice. However, positive responses to Fe-chelate treatments are expected for genotypes with shoot Fe: Mn ratio less than 0.4 when both nutrients are in the sufficiency range. Obviously, such a requirement limits the utilization of Fe-chelate to post-emergence fertilization. [ABSTRACT FROM AUTHOR]

Most agricultural soils in Iran are usually low in organic matter (OM). Therefore, increasing OM in these soils is of great concern. Environmental pollution caused by chemical fertilizers has created an interest in the integrated use of organic wastes with inorganic fertilizers. The main purpose of this greenhouse study was to evaluate the impact of two organic wastes and phosphorus (P) on the growth, and elemental composition of spinach (Spinacia oleracea L.) and soil chemical properties. Treatments consisted of four levels of municipal waste compost, MWC (0, 1, 2, and 4%), five rates of poultry manure, PM (0, 1, 2, 3, and 4%), and three P levels (0, 25, and 50 mg kg−1 as KH2PO4). Application of P and MWC alone or in combination significantly increased the top dry weight of spinach. However, spinach growth was markedly increased up to 3% PM and suppressed with the higher rate, probably due to an excess of soluble salts in the soil. Moreover, the enhancing influence of P on spinach seedling growth was more pronounced at lower levels of MWC and PM. Plant P concentration tended to increase with increasing P, MWC, and PM application rates, whereas nitrogen (N) concentration was only affected by the two organic wastes treatment. Manganese (Mn) concentrations decreased, and copper (Cu), lead (Pb), and cadmium (Cd) increased by soil P application. However, P addition significantly decreased zinc (Zn) concentration only in MWC-treated spinach. Spinach plants enriched with either of the two biosolids accumulated more Mn, Zn, Pb, Cd, chloride (Cl), and sodium (Na) than control plants. Furthermore, spinach grown on MWC-amended soil contained higher Mn, Zn, Cu, and Pb and lower N, Cl, and Na than those raised on PM-treated soil. Postharvest soil sampling indicated that application of the two biosolids significantly increased concentration of soluble salts, (ECe), OM, TN, NaHCO3-extractable P, and DTPA-extractable iron (Fe), Mn, Zn, Cu, Pb, and Cd. [ABSTRACT FROM AUTHOR]

Iron (Fe) deficiency is common in calcareous soils. Application of FeEDDHA is effective in correction of Fe deficiency in such soils. However, it may decrease concentration and uptake of some micronutrients including manganese (Mn). The effect of Fe on Mn status of different soybean [Glycin max (L.) Merr.] genotypes was studied in a greenhouse experiment in a completely randomized design with three replicates. The treatments consisted of three Fe levels (0, 2.5, and 5 mg Fe kg−1 as FeEDDHA) and 12 soybean genotypes. Results showed that application of Fe increased top dry weight of Wells, Black hack, Elgin, and A3237, but decreased that of Steel and A3935 and had no effect on other genotypes. Addition of Fe increased concentration and uptake of Fe, but decreased that of Mn in all genotypes. The Fe:Mn ratio greater than 0.4 in plant tops when both Fe and Mn were in the nutrient sufficiency range were considered to be an indication of tolerance to Fe deficiency, as these genotypes did not respond to Fe fertilizer. Regression equations showed that the highest reduction of Mn concentration occurred at 2.5 mg Fe kg−1. Manganese concentration was reduced by 13, 17, and 19% due to the dilution effect only in Black hack, A3237, and Elgin, respectively. Iron application did not cause either Fe toxicity in soybean or suppression in root:shoot ratio. It seems that Fe addition reduced Mn concentration in some soybean genotypes probably either by reduction of Mn concentration and/or translocation of Mn from root to shoot. The fact that soybeans are highly sensitive to Fe and Mn deficiencies and use of expensive FeEDDHA might accentuate Mn deficiency or imbalance in soybeans demonstrates a need to screen out and select soybean genotypes resistant to Fe stress. [ABSTRACT FROM AUTHOR]