Growing vegetables
Azadeh Omidi; Ali Reza Astaraei; Hojat Emami
Abstract
IntroductionChromium pollution of the soil due to natural processes or industrial activities such as metal refining, chrome plating, stainless-steel production, leather tanning, and chemical dye production is a globle environmental issue. Excessive soil Cr levels cause detrimental effects on plant physiological ...
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IntroductionChromium pollution of the soil due to natural processes or industrial activities such as metal refining, chrome plating, stainless-steel production, leather tanning, and chemical dye production is a globle environmental issue. Excessive soil Cr levels cause detrimental effects on plant physiological processes including photosynthesis, water relations and mineral nutrition as well as the growth of roots, stems and leaves, which may decrease the biomass and yield of plants. Currently, soil application of organic amendments particularly humic acid seems to be an effective procedure to enhance relative plant tolerance to Cr stress. Humic acids are complexes of heterogeneous poly electrolytes with abundant functional groups that act as a weak poly electrolytic acid. Their structures, the degree to which these functional groups are protonated or ionized and environmental conditions influence the interaction between HA and soil pollutants. The complex compounds form by interaction of HA and heavy metals that cannot be uptaken by plants. Humic acid may play a significant role in the mobility and uptake of Cr which leads to a significant increase in plant biomass and growth. The aim of this research was to investigate the ability of humic acid to reduce Cr uptake and translocation by lettuce (Lactuca sativa L.) from Cr-contaminated soil. Materials and MethodsThe present study through a greenhouse pot experiment was conducted in the greenhouse of Ferdowsi university of Mashhad. The experiment was arranged in a factorial manner in a randomized complete design with three replications and treatments consisted of 3 levels of Cr (0, 25, and 50 mg kg-1as K2Cr2O7) and 3 rates of HA (0, 5 and 10 %). The soil samples were dried at room temperature, ground and sieved with a 2-mm mesh screen for further analysis. The bioavailable concentrations of Cr in the soils were assessed by DTPA. Three lettuce seedlings were grown in each pot containing five air-dried soil and watered to a near field capacity with distilled water as needed. After 100 days plant tissues were harvested, carefully washed with deionized water and the leaf, stem and root parts separated. All of them were oven-dried at 65-75 °C to constant weight and the dry weight of lettuce tissue samples was recorded. To determine the Cr concentrations, the tissues were ground, passed through a 0.3-mm sieve and digested in di-acid mixture (HNO3:HClO4). Concentrations of Cr in the digested solutions and soil extractions were determined using an Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES). Translocation factor (TF) is determined from the ratio of the concentration of Cr in the plant’s shoots compared to that in the plant’s roots. Bioaccumulation factor (BAF) was evaluated as defined as the accumulated concentration of Cr in plant divided by concentration to that in respective soil. A two-way analysis of variance was done by using a statistical package, JMP version 8.0. The differences between the treatments were determined using LSD multiple range tests at significance level of P ≤ 0.05 and P ≤ 0.001.Results and DiscussionThe results of the present study clearly demonstrate that all Cr treatments significantly reduced leaf, stem, shoot and root dry weights. In unamended soils, both Cr treatments alone reduced leaf, shoot, stem and root dry weights 83%, 101%, 207% and 65% (for Cr 25 mg kg-1) and 194%, 219%, 355% and 92% (for Cr 50 mg kg-1) respectively as compared to control. Using HA (5 and 10%) and Cr treatments (25 and 50 mg kg-1), showed that leaf, shoot, stem and root dry weights were significantly increased as compared to Cr contaminated control. The lowest values of these parameters were recorded in Cr treatments without addition of HA, whereas at each Cr level, the highest values of them were obtained with application of 10% HA. The Cr concentrations in shoot and root samples significantly were affected by adding HA and Cr levels in soil. It was observed that Cr contents in shoots and roots, transfer factor and bioaccumulation factor of shoots and roots significantly increased by increasing soil Cr levels. Moreover, HA application negatively affected Cr content in shoot compared to Cr treatment alone. The interaction of chromium and humic acid caused a significant decrease in the concentration of chromium in the aerial parts, the shoot accumulation factor and a significant increase in the concentration of chromium in the roots and consequently reduced translocation factor. The highest value of Cr in shoot (47.7 mg kg-1) was obtained in those plants grown in soil with addition of 50 mg kg-1 Cr alone, whereas at each Cr level the lowest value of Cr in shoot was found in those plants grown in soil with the application of 10% HA. HA application in soil increased Cr concentration in root compared with Cr contaminated control. The maximum Cr concentration in the root (367 mg kg-1) and root bioaccumulation factor (28.5) was obtained after exposure to 50 mg kg-1 Cr +10% HA treatment. Also, the regression models showed that the transfer factor and shoot bioaccumulation factor decreased significantly and linearly with increasing shoot dry weight. Moreover, the regression model of shoot dry weight and shoot bioaccumulation factor was able to predict traslocation factor and shoot bioaccumulation factor with Adjusted R2 = -0.78** and R2 = -0.93**, respectively. ConclusionResults demonstrated that Cr toxicity markedly reduced plant growth parameters for instance leaf, stem, shoot and root dry weight and enhanced the concentration of Cr in shoot and root as compared to control. Humic acid application in Cr contaminated soil induced increased plant biomass, root bioaccumulation factor, Cr contents in roots and reduced Cr concentration in leaves, translocation factor and shoot bioaccumulation factor. Therefore, the application of HA specially at higher dose (10%) seems to be a cost-effective and environmentally friendly method for the restriction of Cr accumulation and its transfer from contaminated soil to edible parts of lettuce, thus helping to enhance food security.
Growing vegetables
Javad َAhooei; Ali Reza Astaraei; Reza Khorassani; Amir Lakzian
Abstract
Introduction
Management of municipal wastes as well as their reuse is one of major concerns of researchers in recent decades due to the expansion of urbanization and increase in production of municipal waste. Composting and use of municipal waste is one of the solutions used in the management ...
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Introduction
Management of municipal wastes as well as their reuse is one of major concerns of researchers in recent decades due to the expansion of urbanization and increase in production of municipal waste. Composting and use of municipal waste is one of the solutions used in the management of these materials. Implementation of various additives to enrich and improve the properties of the produced compost is one of the common methods to increase the efficiency of produced compost. Different organic and inorganic compounds are used to enrich the produced compost. The aim of this study was to investigate the effect of two organic compounds (blood powder and bone powder) and a mineral compound (phosphate soil) on the composting properties of municipal waste. It was also our goal to find the effect of these treatments on growth characteristics and concentration of nutrients in shoot of spinach was evaluated.
Materials and Methods
This research was conducted in two stages. The purpose of the first part was to investigate the effect of organic and inorganic additives on the properties of municipal waste compost. Experimental factors included four types of composts including control compost (without additives); compost plus 1% blood powder; compost plus 1% bone powder and compost plus 5% phosphate soil. After sieving the waste and removing the waste leachate, about 60 kg of waste was weighed for each treatment and placed in plastic barrels with a volume of 100 liters for better control of aeration conditions. The compost ripening factors were stable after 90 days, when it was screened and materials were separated, then some of its properties include acidity, electrical conductivity, organic carbon, total nitrogen, C/N ratio, iron, humic acid, fulvic acid, and other parameters including humification ratio, humification index and degree of polymerisation were measured. In the second phase, the effect of compost enriched with blood powder, bone powder and phosphate soil treatments was compared with control treatment (without compost) on growth characteristics and nutrient concentrations in spinach shoots in a greenhouse experiment. For this purpose, pots (with a diameter of 25 cm and a height of 30 cm) were packed with 8 kg of soil in which enriched composts was mixed in 5 g compost/kg of soil ratio. After preparing the pot, the humidity reached 65% of the field capacity and after 25 days, 6 spinach seeds (Spinacia oleracea L.) were planted. After 50 days of planting, the plants were harvested and parameters such as shoot dry weight, leaf area, nitrogen, iron and phosphorus were measured.
Results and Discussion
Results of enriched compost showed that the highest amount of reduction in EC (with 14.5%) and OC (with 8.9%) was resulted in phosphate soil treatment and the highest reduction in C/N ratio (with 46.8%) was related to blood powder treatment. Regarding to the other variables, the highest N and Fe concentrations was related to the blood powder treatment with 2.5% and 706.6 mg/Kg and the highest P content with 1.66% was observed in phosphate soil treatment which had a significant difference with control. Regarding to the Humification indices the highest difference with the control treatment in Fulvic acid content with 24.5% was related to bone powder treatment, that of Humic acid content with 32.4% and Polymerization rate with 43% was related to phosphate soil. In this experiment, the amount of organic carbon was expected to increase in blood powder and bone powder treatments, which was not the case. This may be due to the effect of these treatments on increasing microbial activity such as microbial respiration and increasing the decomposition of organic carbon which ultimately leads to a decrease in the amount of organic carbon. The increase in EC in organic treatments compared to inorganic treatments may be due to weight loss of organic matter and release of various mineral salts. The effect of experimental treatments in the greenhouse section also showed that highest difference in plant dry weight compared to the control was related to the blood powder treatment with 59% increase and regarding to the leaf area with 31.9% increase through application of the blood powder and phosphate treatments. The highest amount of Fe and N absorption in spinach shoots was also observed in blood powder treatment with 1177 mg/Kg and 3.13% respectively. Phosphate soil with high amounts of phosphorus increased the amount of this element in the shoots of spinach. The two combinations of blood powder and bone powder caused a significant increase in these elements in the compost and in most of the measured parameters, due to their high amounts of nitrogen and iron. These two organic substances were significantly different from the control.
Conclusion
The results of this study showed that the enrichment of municipal waste compost using organic and inorganic additives can compensate for the lack of some elements in the compost and further increase the growth of spinach. Adding blood powder increased the concentration of iron and nitrogen in the shoot and decreased the C/N ratio compared to the control treatment. Also, the positive effect of phosphate soil and bone powder are effective in increasing the phosphorus content of compost. In addition, the combination of phosphate soil with municipal waste compost due to the formation of more stable materials such as humic acid and folic acid prevents their subsequent wastage. Finally, it can be concluded that in this experiment, two treatments of blood powder and phosphate soil have the best effect on enrichment and they had increased growth characteristics of spinach and in general, and blood powder was selected as the best treatment.
Saba Nejatie Zadeh; Saeid Malekzadeh Shafaroudi; Ali Reza Astaraei; Nasrin Moshtaghi
Abstract
Introduction: An emerging field of nanotechnology in recent years is the use of nanoparticles and nanomaterials in agricultural systems which is due to their excellent mechanical, electrical, optical, surface properties, crop protection and nano-fertilizers. Titanium dioxide (TiO2) is a class of nanoparticles ...
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Introduction: An emerging field of nanotechnology in recent years is the use of nanoparticles and nanomaterials in agricultural systems which is due to their excellent mechanical, electrical, optical, surface properties, crop protection and nano-fertilizers. Titanium dioxide (TiO2) is a class of nanoparticles which widely used in the food industry, cosmetics, papers, pharmaceuticals, plastics and industrial raw materials. The widespread industrial application of TiO2 is due to its white pigment, ultraviolet blocking property, and chemical features commonly used to alleviate pollutants concentration in water, soil and air. Owing to its increasing use in the industry, a large part of TiO2 residues are released into the environment, and currently, TiO2 nanoparticles are being considered an emerging environmental contaminant. However, there have been a number of studies reporting beneficial effects of TiO2 on growth and physiological traits of crops. It has been postulated that the TiO2-induced improvement of crop growth is not merely related to the promotion of photosynthesis; other biochemical processes especially nitrogen metabolism are also involved in this event. Ethylene diamine tetraacetic acid (EDTA) is a widely used as a chelating agent, i.e., the chemical is able to sequester metal ions such as Ca2+ and Fe3+. EDTA is used as nitrogen source for doping of TiO2 nanoparticles which improves TiO2 photocatalytic features. The present study was conducted to investigate the effects of TiO2 nanoparticles and EDTA on growth indices and biochemical parameters in spinach (Spinacia oleracea). For detailed evaluation of treatment effects, different concentrations of TiO2 nanoparticles were sprayed on spinach leaves and the samples were collected in a time course.
Materials and Methods: A factorial experiment was carried out in the form of completely randomized design (CRD) with three replications. Soil samples were taken before cultivation of spinach (S. oleracea) seeds (Var VIROFLAY) and analyzed for nutrients’ concentration. Treatments include different levels of TiO2 (T1=0, T2=0.05mg/l and T3=0.1mg/l) and two concentrations of EDTA (E1=0 and E2=130mg/l) sprayed on spinach plants in research greenhouse of agriculture faculty, Ferdowsi University of Mashhad. Aqueous solutions of nanoparticles were treated by ultrasound for 10 min to enhance homogeneity. The solutions were sprayed on the plant at six- leaves stage. The plant samples were taken before reproductive phase for measurement of biochemical parameters. Nitrogen content of plant samples was measured by PDV 500 Macro- Kjeldahl device; Potassium content was determined by 310c flame photometer; phosphorus concentration in plant samples was measured by spectrophotometer model 2100. Chlorophyll and carotenoid contents were measured by the method proposed by Lichtenthaler (1978). For analysis of growth parameters, plant samples were taken a week after TiO2 treatments and leaf area, shoot fresh/dry weight, stem length, internode length, root area, root fresh/dry weight and total root diameter were measured.
Results and Discussion: Application of 0.05mg/l of TiO2 nanoparticles without EDTA resulted in 13.5% and 9.48% increase in nitrogen and protein; respectively, however by increasing nanoparticles to 0.1mg/l, nitrogen and protein content in the treated plants were respectively reduced to 21% and 19.57% of those of control group (p
