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  Spinach is a leafy vegetable rich in nutrients and can be consumed either raw or prepared in various ways. Incorporating micro-elements like Zn and Fe can increase nutrient concentration in agricultural products and boost plant yield. This, in turn, plays a crucial role in improving food quality and promoting better health for society. High concentrations of Zn can impede plant growth by affecting photosynthesis and oxygen-free radical production. Conversely, Fe is a vital micronutrient contributing to several plant metabolic processes. This study aims to identify the optimal levels of Fe and Zn elements to enhance spinach yield, element concentration, and vegetative growth.

The plants were cultivated in washed sand media (free from any nutrients). Plants were treated with Zn (0.22, 5, and 10 mg L-1) and Fe (3, 6, and 12 mg L-1). After the first two leaves appeared in each pot, 500 ml of nutrient solution was manually added.

The ANOVA results indicate that varying levels of Zn and Fe have a significant impact on various traits in spinach, including leaf size, fresh and dry shoot, and root weight, photosynthetic pigments, total antioxidant activity, total soluble protein and carbohydrate content, as well as leaf and root elements. It is important to note that the nutritional components of both spinach leaves and roots were impacted by the combinations of treatments applied. Specifically, the levels of Mg, Zn, and Cu increased after using varying concentrations of Fe and Zn compared to those plants watered with the lowest levels of these minerals. The simultaneous application of Zn and Fe increased the Fe content of leaves and roots. Still, with the increase in the concentration of these treatments, it was observed a reduction in the Fe content so that the lowest amount of Fe in the leaves and roots was observed in the highest concentration of Zn in the food solution (12 mg L-1 Fe + 10 mg L-1 Zn). Spinach plants under irrigation by 5 mg L-1 Zn + 6 mg L-1 Fe had the highest leaf K content, which improved by 31.79% compared to the control treatment. When the concentration of Zn in the nutrient solution was increased to 10 mg L-1, it resulted in a decrease in K content in both leaves and roots. The treatment of Fe 6 mg L-1 + Zn 5 mg L-1 had the highest fresh weight (33.977 g) and dry weight (3.487 g) content and also resulted in an increase in leaf size (length 8.933 mm and width 4.477 mm). However, with the increment of Fe concentration to 12 mg L-1 + 10 mg L-1, these traits showed a significant decrease, as well as the highest content of chlorophyll a and b and carotenoids were obtained at a concentration of 6 mg L-1 of Fe + 5 mg L-1 of Zn, which showed an increase of 289, 687 and 406% compared to the plants treated with the lowermost Zn and Fe concentration, respectively, and the lowest values of chlorophyll a and b, and carotenoids were found in the control plants, the protein content varied from 1.038 mg g-1 FW in the lowest treatment to 4.256 mg g-1 FW in the 12 mg L-1 Fe + 5 mg L-1 Zn treatment, the highest total soluble content was observed in 6 mg L-1 Fe + 5 mg L-1 Zn, which was led to an increase of 72%. The lowest total soluble carbohydrate was also observed in the control plants. The highest and lowest total antioxidant activity was recorded in 12 mg L-1 Fe + 5 mg L-1 Zn (10.75%) and the control spinach plants (6.705%), respectively.

Increasing the Zn concentration up to 10 mg L-1 caused a reduction in growth parameters and the content of photosynthetic pigments and elements of K and Fe in leaves and roots. However, the measured trait concentration for the studied treatments was higher than in the control plant. The present results showed that the spinach plant is somewhat resistant to the high concentration of Zn micronutrient. Based on the obtained results, Fe and Zn treatments combined were more effective for promoting healing than separate treatments. 6 mg L-1 of Fe and 5 mg L-1 of Zn was the most effective treatment.

Okra (Abelmoschus esculentus) is a tropical and sub-tropical vegetable that is mainly grown by transplantation. Technological advances in agriculture have also contributed to the progress of the transplanting industry because they have reduced the cost of transplant production. Arbuscular mycorrhizal fungi (AMF) have symbiotic relationship with many plants’ root and their importance in growth and yield improvement has been proven. Mycorrhizal symbiosis is one of the most common symbiosis in plants. The main advantage of AMF for host plants is the expansion of the root penetration zone. Also, seaweed extract (SWE) acts as a bio-stimulant to plant growth enhancement. These products are widely used in improving agricultural sustainability and can actually facilitate the production process by reducing environmental effects. And, the co-application of AMF and SWE could be attributed to promoting the growth and yield of agricultural crops.

In order to study the effect of SWE foliar application and AMF inoculation on okra transplants, a factorial experiment was conducted based on a completely randomized design with two factors and four replications under greenhouse condition. The first factor was AMF (Glomus mosseae) inoculation at two levels included 0 (as control) and 5 g kg-1 and the second factor was SWE (Ascophyllum Nodosum) foliar application at four levels included 0 (as control), 1, 2 and 4 g L-1. The morphological traits of the transplants such as plant height, number of leaves, length and width of the leaves, fresh and dry weight of the root and shoot, and stem diameter were measured. Also, in order to assess physiological responses of transplants to used treatments, some important traits such as photosynthesis pigments content, total soluble carbohydrates, total soluble proteins, total antioxidant activity and some macro- and micronutrients were evaluated.

The results showed that the morphological, physiological, and biochemical characteristics, as well as the nutrient content of okra were significantly affected by SWE spraying and AMF inoculation. These treatments improved the growth parameters, photosynthetic pigments content, osmolytes (total soluble carbohydrates and total soluble protein), total antioxidant activity, and macro and micro-nutrients of okra transplants. The foliar spraying of 4 g L-1 SWE along with AMF increased the stem diameter, plant height and leaf length by 72, 85 and 55%, respectively, compared to the control plants. AMF inoculation improved the leaf width by 12.83% compared to control. Foliar application of SWE at 4 g L-1 concentration increased the leaf width by 25% compared to control. The treatment of 4 g L-1 SWE along with AMF inoculation caused an increase in fresh and dry weight of root by 132.83 and 204.54 %, respectively. The highest content of chlorophyll a (36.51 and 35.79 mg g-1 FW) was observed in transplants treated with SWE 2 and 4 g L-1 and AMF, respectively, and the lowest content (12.01 mg g-1 FW) was observed in control. The highest content of chlorophyll b (22.21 mg g-1 FW) was obtained in transplants treated with SWE 4 g L-1 and AMF, and the lowest value was recorded in control (6.51 mg g-1 FW). Foliar spraying of SWE and AMF inoculation led to a 2.7-fold enhancement in total soluble protein compared to control. The highest antioxidant activity (35.89 %) was recorded in transplants treated with SWE 2 g L-1 and the lowest value (25.44 %) was for control plants.

The results of the current study have shown that application of SWE and AMF as separate or combined treatments led to a significant improvement in okra transplants morphological characteristics such as plant height, leaf length, number of leaves, stem diameter, leaf width, and stem and root fresh and dry weight, as well as enhanced physiological traits such as protein content, chlorophyll a and b content, antioxidant activity rate, carbohydrate and carotenoid content, and the amounts of macro- and micro-nutrients. Based on obtained results of this study, foliar application of SWE at concentration of 4 g L-1 along with AFM inoculation could be recommended as useful treatment to produce okra transplants with suitable morpho-physiological characteristics.

One of the principle factors influencing the plant's growth parameters and yield is nutrition with micro-elements. Boron and zinc are dominant micro-nutrients directly or indirectly affect the plants biochemical potential and hence the yield of plants. In the present experiment, we aimed to study the effects of Zn and B on some growth attributes and quality of Lactuca sativa L. cv. 'paris island'. The experiment was conducted at the Research Greenhouse of the University of Maragheh as factorial based on CRBD with Zn (0, 5 and 10 mg L-1) from ZnSO4,7H2O and B from H3BO3 at three levels (0, 2 and 4 mg L-1 ) with three replications. The results revealed that with increasing Zn concentrations in the nutrient solution, the fresh weight, dry weight, chlorophyll index, chlorophylls a and b content, total chlorophylls content, carotenoids amount, soluble proteins concentration and Zn concentration were increased in the lettuce leaf tissue (p≤0.01). Furthermore, with increasing nutrient solution's B concentration, the proline, MDA, GPX, CAT and APX levels and activities as well as the boron content in the plant tissue were significantly influence and increased. Zn up concentrations under boron high availability reduced the aforementioned traits quantities (p≤0.01).

To assesse the iron and silicon effects on the yield and physiological characteristics of green pea, Wando cultivar by ASGrow Corporation was used in three levels of iron chelate (0.05, 0.1 and 0.3 gr per l-1) and silicon (0, 14 and 28 mg per l-1), as a factorial experimental in completely randomized design with three replications. In this experiment, characterisics such as fresh and dry weight of grain, the number of grain per pod, concentration of Fe, Cu, Mn, Zn and Si in leaf and grain were measured. Results showed that the interaction of Fe and Si was significant at p<0.01 on grain fresh and dry wigeht, concentratin of leaf and grain Fe, leaf Mn, leaf and grain Zn and leaf Si and the application of Fe and Si was significant separately, on other traits such as number of grain per pod, concentration of leaf and grain Cu, Mn and Si in grain. The Mean squares showed that the application of Fe and Si significantly increased fresh and dry grain weight and Si laef concetration and decreased the concentratin of leaf and grain Fe and Mn as well as grain Mn. The enhancement of Fe and Si application separately decreased the concentration of Mn, Cu and zinc leaf and grains, but the Si concentration of leaf and grain were increased by Si application. The concentration of Fe, Mn, Cu and Zn were decreased in leaf and grain because of antagonistic effects. It can be concluded that Si reduces the harmfull effects of high levels of iron toxicity and the application of 0.1 g/l and 25 mg/l can be recommended as the best treatments.

The presence of cadmium in the soil is a major threat to plant growth and productivity. Plants often accumulate cadmium in their edible part, reducing the yield and quality of the product. In order to evaluate the effect of different concentrations of potassium (100, 200 and 300 mg L-1) under different levels of cadmium (0, 2 and 4 mg L-1) stress in tomatoes and potassium efficiency in reducing stress effects, a factorial experiment based on a completely randomized design was carried out with 3 replications. The results showed that with raising the cadmium concentration, malondialdehyde content, hydrogen peroxide content and guaiacol peroxidase activity were increased. The interaction effect of cadmium and potassium on the Fe concentration in the fruits and Zn concentrations in the leaves and fruits of tomatoes was not significant; however, the use of each of them alone had a significant effect; so, potassium consumption increased the concentrations of Fe, Zn and K in the fruits and decreased the malondialdehyde and hydrogen peroxide. The results of greenhouse experiments showed that the use of potassium nitrate fertilizer improved the efficiency of the plant phytoremediation in reducing the cadmium stress, although it is necessary to continue research in the field.

The chickpea (Pisum sativum) are an herbaceous annual plant, with a short growth period which gives the best result in a cool climate. Although, exictence of some heavy metals like iron in soil and nutritional solution are essential for growth of plants but the high concentration of them can be an inhibitor of growth and causing toxicity by creation of oxidative stress and increasing ROS toxicity. On the other hand, silicon can increase the yieid and quality of the crops under stress conditions caused by the toxicity of heavy metals such as iron, manganese and aluminum in plants. In this research, the effects of silicon in presence of several iron levels on some biochemical traits in chickpea were studied.

The experiment was conducted as a factorial based on a completely randomized block design which Si at three levels (0, 14 and 28 mg/l) from sodium metasilicate (Na2SiO3.5H2O) and Fe in three levels (0.05, 0.1 and 0.3 g/l) from iron chelate used at three replications in greenhouse conditions. Hoagland's solution was used as nutritional solution, the amounts of Si and Fe were added to it and then consumed. Biochemical traits such as total chlorophyll, total soluble protein, malondialdehyde (MDA) level, hydrogen peroxide (H2O2) concentration, and specific activity of catalase (CAT), guaciole peroxidase (GPX) and ascorbate peroxidase (APX) were evaluated.

The results showed that the interaction of Fe and Si on total chlorophyll, protein, hydrogen peroxide, CAT and APX were significant. The increasing of Fe concentration, chlorophyll and protein reduced but Si caused increasing of them. In other words, by application of Si, the effects of stress which caused by high concentrations of Fe diminished. In the interaction of Fe and Si on H2O2 content, Fe raised and Si decreased it at all the levels of the treatments. Both Fe and Si treatments increased the activity of CAT and APX enzymes. On the other hand, the interaction of treatments on GPX activity and MDA content were not significant. But the simple effects of the treatments caused significant differences in GPX and MDA, so that Fe increased both of them, but Si reduced MDA and increased GPX.

Based on the results, it can be concluded that high concentrations of Fe in chickpea, such as most plants, increase the oxidative stress and Si has somewhat reduced the effects of this stress. Therefore, Si can be studied and used as a useful ingredient in cutting down biotic and abiotic stresses. Based on this study, 0.1 g/l of Fe along with 28 mg/l had the best effect on improving some biochemical characteristics of chickpea.

Manganese is a microelement for plants and is not actually counted as a metal pollutant. Manganese toxicity in some agricultural soils due to its excessive regeneration leads to undesirable symptoms in plants. Silicon is well known as reducing stress and toxic effects of some elements. A hydroponic experiment was conducted to evaluate the effect of silicon and manganese on leave of lettuce (Lactuca sativa L. cv. Siahoo) in greenhouse of Agricultural Faculty of Maragheh, Iran in 2016. The experimental design was completely randomized factorial design with three replicates. The treatments were three level of manganese (0.5, 2.5 and 5 mg/l) from MnSO4 source and three level of silicon (0, 14 and 28 mg.L-1) from Sodium metasilicate source. The results showed that with increasing manganese concentration, the levels of malondialdehyde, catalase, ascorbate peroxidase and hydrogen peroxide increased and total protein and fresh weight and dry weight of plant decreased. The highest plant fresh and dry weight loss was observed in 5 mg.L-1 manganese. Sodium metasilicate significantly reduced the level of malondialdehyde and hydrogen peroxide and increased the activity of the enzyme catalase, ascorbate peroxidase, total protein, plant fresh and dry weight. In general, application of high concentrations of manganese in nutrient solution decreases the plant growth and yield, while silicon application reduce the toxic effects of manganese and enhances the plant yield.

This greenhouse experiment, consisted of a completely randomized factorial design, was conducted to investigate the changes in antioxidant enzyme activities of lettuce plants cv. Syahoo inoculated with Piriformospora indica fungus under different levels of zinc (0, 2.5, 5 and 10 mg l-1) in the research laboratory of Maragheh university in spring 2016. Fungal treatment was added at two leaf stage of seedling on the lettuce roots in the sandy substrate. The plant samples, at 35 days after sowing, were measured for dry and fresh weights of shoot, total soluble protein, malondialdehyde (MDA) concentration and activities of antioxidant enzymes superoxide dismutase (SOD), guaiacol peroxidase (GPOX), and catalase (CAT). The results revealed that the effect of P. indica and zinc application on dry and fresh weights of shoot, total soluble protein and activity of SOD were significant at P≤0.01. The main effect of zinc on MDA concentration, activity of GPOX and CAT was significant at P≤0.01. Highest amount of dry and fresh weights and total soluble protein, and maximum activity of SOD were obtained in presence of P. indica under 10 mg L-1 Zn. Maximum activity of CAT, GPOX, and MDA concentration were observed in treatments without zinc application. Results from our research showed that inoculation by P. indica and zinc application (especially at 10 mg L-1) have an important role in enhancing the growth parameters and modulating the activities of antioxidant enzymes in lettuce.

Plants often accumulate cadmium (Cd) in their edible parts that causes a decrease in crop yield and quality. In order to evaluate the effect of different concentrations of potassium (100, 200 and 300 mg/L) in tomatoes under Cd stress (0, 2 and 4 mg/L) and its efficiency in reducing stress effects, a factorial experiment was carried out based on completely randomized design with 3 replications. Results showed that application of Cd significantly increased Cd concentration in fruits. Existence of Cd in nutrient solution significantly decreased fresh and dry weight of fruit, firmness, titratable acidity, and finally yield. Also, the negative effect of Cd stress on fruit titratable acidity and firmness was neutralized by increasing the potassium (K) level. Potassium caused an increase in total soluble solids and color by affecting a* color parameter and fruits had more red color and ripeness. The treatments had no significant effect on fruit pH and pericarp thickness

Todays, contamination of agricultural soils by different ways of salinity is increasing as a result of human and environmental factors that would reduce yield and quality of agricultural crops. However, there are some plants that can tolerate some degrees of salinity. Tomato is one of the horticultural crops, moderately sensitive to salinity even that salinity can improve its quality. So, a study was conducted using four varieties of tomato under normal and salt stress (3, 6 and 9 dS m-1) hydroponic conditions to evaluate tomato quality. The results showed that increasing in salinity improves the quality and taste of tomato with a reduction in pericarp thickness, fresh weight and total protein. However, when the degree of salinity exceeds 6 dS m-1, a significant difference was observed in fruit yield which was variety dependent. Also, there is a significant difference between salt tolerance, performance, and taste of different varieties. Furthermore, it is found that the activity of guaiacol peroxidase and catalase enzymes increased as well as an increase in the level of salinity. Tomato cv. Super Chief with the highest number of fruits per plant, high level of proline as well as catalase activity, has the best performance against salinity levels of soil and was more resistant to salinity than other varieties. Also, tomato ‘Super Chief’ had the highest taste index with a slightly decline in the yield. Salt stress tomatoes have more carotenoid than controls but the level of 9 dS m-1 salinity was not tolerable by all varieties.

Cadmium(Cd) is a non-essential and toxic element, without any metabolic significance, whereas zinc(Zn) is an essential element. Since both Cd and Zn have similar electronic configurations and valence, the increase of Zn in rhizosphere can adjust the toxic effects of Cd. To study the effects of Cd and Zn on growth and yield of Beta vulgaris L. cv. dark red, a greenhouse experiment was carried out in a factorial experiment with a randomized complete block design and four replications. Three levels of Cd (0, 45 and 90 µM) and three levels of Zn(0.5, 155 and 310 µM) were added to nutrient solution. The seed bed was perlite and the seeds of dark red cultivar of red beet were planted. Results showed that Cd application significantly increased Cd concentration but decreased Zn concentration in leaves and roots. Application of Cd significantly decreased photosynthesis, chlorophyll content, leaf number, leaf area and yield in plants. Application of Cd in 90 µM (Zn1Cd2) decreased dry weight, leaf area, photosynthesis, chlorophyll content and Zn concentration by 72%,32%,39%,29% and 60% respectively, compared with control(Zn1Cd0). Application of Zn in nutrient solution significantly increased yield, chlorophyll content and leaf number, leaf area and also Zn concentration in leaves and roots of red beet. Application of Zn increased Cd concentration in leaves and roots of red beet. The interaction between Zn and Cd in chlorophyll content was statistically significant and application of Zn alleviated Cd toxic effect on chlorophyll degradation.

Cadmium (Cd) as a heavy metal induces some disorders in normal metabolism in plants. Furthermore، Silicon (Si) is able to ameliorate the deleterious effects of some toxic elements like Cd. Keeping this in view، an experiment was conducted to find out the effects of Cd and Si on growth and some physiological aspects of Beta vulgaris L. cv. Dark Red. The experiment was arranged as a factorial scheme based on randomized complete block design with four replications. Three levels of Cd (0، 2. 5 and 5 mg L-1) from CdSO4 and three levels of Si (0، 28 and 56 mg L-1) from Na2SiO3 were added to nutrient solution. Perlite was used as growing media and the seeds of red beet were planted in the pots (14 L). The results showed that Cd addition significantly increased Cd concentration in leaves and roots. Application of Cd significantly decreased photosynthesis rate، chlorophyll content، leaf number، leaf area and total soluble solids (TSS) in the roots. Additionally، increased Cd concentration in the growing media led to increased malondialdehyde (MDA) and hydrogen peroxide (H2O2) concentration in leaves. At 5 mg L-1 Cd، concentrations of H2O2 and MDA in leaves were 2. 4 mM/g Fwt and 84. 5 nM/g Fwt، respectively. The rate of photosynthesis in 5 mg L-1Cd، control and 56 mg L-1 Si treatments were 7. 9، 18. 25 and 25. 76μ mol CO2 m-2s-1، respectively. Application of Si in nutrient solution significantly increased leaf number، leaf area، photosynthesis، chlorophyll content، total soluble solids (TSS) in roots and dry weight in plants. Increased Si in nutrient solution had no effect on the Cd concentration in leaves and roots of red beet. Nevertheles، malondialdehyde (MDA) and H2O2 concentrations in leaves of red beet were reduced with Si addition to the nutrient solution. In general، it is recommendable to take into consideration the benefits of Si addition to red beet growth media، but more investigations are needed.