Journal of Soil and Plant Interactions

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A completely randomized factorial experiment was set up with 16 treatments and three replicates to study the effect of nitrogen and boron on yield, shoot and root dry weights and leaf concentration of nutrient elements in hydroponically grown tomato in greenhouse of Agricultural College of Zanjan University in 2008. In this experiment, tomato seed of Rio Grande Ug was selected and simple and interaction effect of four levels of N (100, 200, 300 and 400 mgL-1) and four levels of B (0.5, 1.0, 1.5 and 2.0 mg L-1) on tomato yield, shoot and root dry weights and leaf concentration of nutrient elements was investigated. The results indicated that the simple and interaction effect of nitrogen and boron on yield and tomato shoot and root dry weights were significant. Te highest yield and root dry weights were obtained in N200B1.0 treatment and the highest shoot dry weight was obtained in N300B1.0 treatment. By increasing the nitrogen level in the nutrient solution, leaf N and Mn concentration increased while B, Fe and Zn concentration of leaves decreased significantly. In contrast, by increasing the boron levels, leaf N, B and Zn concentration increased and Fe and Mn concentration of leaves decreased significantly. With respect to the results of this study, applications of 200 mg L-1N and 1.0 mgL-1 B of nutrient solution are recommended to obtain higher yield and better quality for tomato in hydroponic culture.

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Interveinal chlorosis induced by iron deficiency is considered to be one of the problems in rose production in greenhouses all over the world. This experiment was conducted to elucidate the capability of chlorophyll fluorescence imaging technique to recognize early iron deficiency and also determination of relationship between leaf iron concentration and leaf chlorophyll content index and photosystem II photochemical efficiency of rose flower (Rosa hybrida L., cv. First Red). Rose plants were grown and subjected to 5 levels of iron (1.5, 3, 6, 12 and 24 μM) based on randomized complete blocks design with 4 replicates in hydroponic greenhouse of Wageningen University, The Netherlands. The results revealed that increased concentration of iron in nutrient solution from 1.5 to 24 μM led to the meaningful increase of average photosystem II photochemical efficiency from 0.062 to 0.590 (P<0.01). This was clearly obvious in the map of photosystem II photochemical yield of rose leaves. The results indicated significant (P<0.05) correlations between leaf iron concentration and leaf chlorophyll content index (r= 0.91) and average photosystem II photochemical efficiency (r= 0.85). Also, a significant correlation (P<0.05) was found between leaf chlorophyll content index and photosystem II photochemical efficiency (r=0.86). The results clearly demonstrated that it is possible to detect early hidden hunger of iron in rose flower with the use of chlorophyll fluorescence imaging and therefore increasing the yield and quality of rose flower in greenhouses.

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Silicon (Si) nutrition may alleviate biotic and abiotic stresses including heavy metal deficiency and toxicity in plants. Iron deficiency and toxicity are important limiting factors in growth of rice. In the present study, role of Si nutrition on alleviation of iron deficiency and toxicity was investigated in rice plants. Plants were cultivated in greenhouse in hydroponics, using Yoshida solution, under different iron treatments (0, 2, 10, 20, 50, 100 and 250 mg/L as Fe- EDTA) and Si nutrition (0 and 1.5 mM as sodium silicate). Results revealed that both iron deficiency and toxicity imposed significant reduction in fresh and dry weight and length of plants. The activity of catalase was decreased in shoots due to iron deficiency. Activity of catalase in roots and cell wall peroxidase in shoots increased under iron toxicity compared with control plants. Si nutrition increased Si content in plants and improved plant growth in both iron deficiency (not in the absence of iron) and toxicity. Application of Si increased the activity of catalase in shoots and polyphenol oxidase in both roots and shoots under iron deficiency. Also, the activity of catalase in roots and polyphenol oxidase in shoots raised following iron toxicity. This in turn may reduce the oxidative stress in plants. In addition, increase of lignin in extreme iron toxicity due to Si nutrition may enhance sites of iron absorption in plant cell walls and decrease iron toxicity. The results indicated that Si nutrition could ameliorate harmful effects of iron deficiency and toxicity in rice plants possibly through improvement of antioxidant enzyme activity and reduction of oxidative stress.

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In order to assess the effects of different levels of nitrogen (N) and foliar application of iron amino chelate on yield and growth traits of dill medical plant, a factorial experiment was conducted in 2011 using a completely randomized design and three replications. In this experiment, five levels of N (0, 50, 100, 200 and 400 kg/ha N from urea source) and two levels of foliar spray of iron amino chelate (with and without foliar spray) with concentration of 2 g/liter were used. At the end of growth period, fresh and dry weight of aerial parts, leaf, stem and roots, ratio of fresh and dry leaf weight to stem weight, height, stem diameter, 1000-seed weight and iron concentration and uptake in the aerial parts were measured. The results of ANOVA showed that the effects of N were significant on all measured traits, except fresh and dry weights of roots. Foliar spray of iron amino chelate increased significantly all measured traits, except fresh and dry weights of roots and plant height. The interactive effects of N and foliar spray were significant on all measured traits except the fresh and dry weight of stem, dry matter, ratio of fresh weight of leaf to stem, fresh and dry weights of roots, and iron concentration and uptake in the aerial parts. The highest fresh and dry weights of aerial parts (714.2 and 102.7 g/m2, respectively) were obtained from the application of 400 kg N/ha plus foliar spray of iron amino chelate. The lowest fresh and dry weights of aerial parts (199.7 and 45.6 g/m2, respectively) were obtained in the control treatment.

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In drought stress conditions, besides the inhibition of water uptake, the plant nutrients availability and uptake are also limited. Proper nutrition is known as a management procedure for plant production under different environmental-stress conditions. Generally, the combined effects of drought and deficiency of potassium and zinc on plant water content and some physiological parameters reduce yield quantity and quality. This investigation was conducted to assess the interactive effect of different levels of potassium as KNO₃ (0.6, 3 and 6 mM) and zinc as ZnSO₄ (0, 1 and 2 μM), under drought stress conditions induced with PEG 6000 (0, 55 and 110 g/L PEG 6000) on some water status indices and physiological parameters of tomato in hydroponic culture. The results showed that interaction of drought, potassium and zinc on shoot and root dry weight, leaf chlorophyll and proline content and percentage of root ion leakage was significant. Both potassium and zinc improved water status of the plants however the effect of zinc on leaf water potential was not significant. Drought stress increased the chlorophyll content and decreased the sulfhydryl groups. Application of a high level of potassium in the nutrient solution increased root ion leakage.

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To date, limited research has been done worldwide on uptake and translocation of nanoparticles (NPs) by plants. To evaluate such processes, soybean (Glycine max L.) was cultured in modified Hoagland nutrient solution containing Fe3O4 NPs with concentration of 60 mg/L, and 33 mg/L iron chelate (Fe-EDTA) was taken as control. After 28 days, the strength of magnetic signal was measured in different organs of the soybean by vibrating sample magnetometer (VSM) instrument. Result showed no magnetization signal from the control plants, but signals with various strengths were found in the tissue samples of the treated plants. Strong magnetic signal in soybean leaves clearly indicated the uptake and translocation of Fe3O4 NPs by roots and xylem. The strongest magnetic signal (138 memu/g) was detected in roots, and transfer coefficient of NPs from roots to leaves was about 0.9 percent. Exudates and surface charge of roots caused accumulation of magnetite NPs on soybean roots' surface. A small fraction of particles moved through simplastic pathways into the xylem and streamed to leaves via sap flow. NPs were accumulated in the crown more than other aerial parts, due to vascular change in structure (root to shoot). In summary, results demonstrated that Fe3O4 NPs can be taken up by soybean and be translocated to other plant tissues in molecular form

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One of the fast responding methods of plants to fertilizer application is foliar application, which saves fertilizer consumption too. Foliar application of micronutrients is a useful method, especially when roots are unable to absorb necessary elements from soil. The amount of available iron (Fe) in calcareous soils, with high pH, is low for sensitive plants, such as sorghum, to Fe deficiency. To compare the effect of foliar application of different Fe sources on growth traits, concentration and uptake of nutrients in sorghum, a greenhouse experiment was conducted as a completely randomized design with three replications. Treatments consisted of three levels of Fe (0, 90 and 180 mg Fe/L) from three sources of Fe (Fe nano-chelate, Fe-EDDHA and FeSO4.7H2O). Results showed that application of all three sources of Fe increased shoot and root dry matter yield, plant height, leaf chlorophyll content, shoot Fe concentration and uptake as compared to control treatment. Foliar application of Fe reduced concentrations of P and Mn in shoot, but had no significant effect on root P, Mn and Fe concentrations. Concentration of Zn and Cu in shoot and root of sorghum was not affected by level of Fe application. Based on the results of this experiment, foliar application of FeSO4.7H2O compared to Fe-EDDHA and Fe nano-chelate can increase growth and improve some characteristics of sorghum plants under greenhouse conditions. This result is economically affordable as well.

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Presence of heavy metals (such as lead, Pb) in plants is one of the major environmental stresses that decrease plant growth. Therefore, it is essential to determine the threshold of the plants' tolerance to these elements. In this regard, to evaluate the effect of different concentrations of Pb on eco-physiological traits of petunia plant, an experiment was carried out in the hydroponics greenhouse of Tabriz University, Tabriz, Iran, as a completely randomized design with 8 treatments and 4 replications. Treatments consisted of different concentrations of Pb (0, 0.25, 0.5, 0.75, 1, 1.5, 2 and 4 mg/L as Pb(NO₃)₂). After applying the treatments, at the end of the growing season, the eco-physiological indices including photosynthesis, transpiration, stomatal conductance, stomatal resistance and leaf temperature were measured. Results showed that concentrations higher than 0.75 mg/L Pb(NO₃)₂ reduced the rate of photosynthesis, transpiration and stomatal conductance as compared to control. The highest stomatal resistance (8.754 M/m².s) was observed in 4 mg/L treatment though it didn't have significant difference with 1.0, 1.5 and 2 mg/L treatments. The lowest stomatal resistance (7.285 M/m².s) was seen in 0.25 mg/L treatment, which had no significant difference with control. The highest leaf temperature (33.26 ْC) was observed in 2 mg/L treatment though it didn't have significant difference with 1.5 and 4 mg/L treatments. The lowest leaf temperature (26.19 ْC) was obtained in the control treatment. After 0.75 mg/L, the increase in leaf temperature was sensible. Based on the results, it appears that in soils having Pb concentration of &le 0.75 mg/L, petunia plants are recommendable for cultivation in landscapes, accumulation of Pb, and phytoremediation.

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Mint is an important medicinal herb that is cultivated in different parts of the world. In order to investigate the effects of salinity stress on morphological characteristics of spearmint (Mentha spicata L.), an experiment was conducted in 2013, based on complete randomized design, under hydroponic conditions, at Research Greenhouse of Faculty of Agriculture, Ferdowsi University of Mashhad, Iran. Treatments were five salinity levels (0, 30, 60, 90 and 120 mM of sodium chloride) with four replications. Growth medium was 2:1 cocopeat to perlite, and complete nutrients solution was used. Supplying plants’ nutrients was twice a week along the irrigation water application. When plants’ height was 30 cm, salinity treatments were applied and were continued till full flowering. At the end of the experiment, morphologic traits including plant height, number of main stems, number of lateral branches, leaf area, specific leaf weight, stem diameter, number of nodes, fourth internode length, and spike length were measured. Results showed that salinity stress had significant effects on leaf area, fresh and dry weights of leaf, stem and root, plant height, number of lateral branches, number of nodes, fourth internode length, and spike length. The highest leaf area, leaf dry weight, plant height and number of lateral branches were observed in control treatment. The lowest leaf area and leaf dry weight were obtained in salinity level of 120 mM, and the lowest plant height and number of lateral branches were observed in salinity levels of 90 mM and 120 mM. Salinity had no significant effect on fresh weight of shoot to root ratio, fresh weight of leaf to root ratio, specific weight of leaves, number of main stems and stem diameter. According to the results, it appears that spearmint is sensitive to salinity stress and it can't tolerate salinity levels higher than 30 mM sodium chloride.

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Recently, attentions have been taken on the investigations regarding the use of nano-sized compounds in different fields including agricultural sector. Due to the importance of evaluating the fate and operation of nano-particles in plant systems, in this survey, responses of 13 wheat genotypes to the effect of nano-iron chelate fertilizer in the Hoagland solution under the conditions of ordinary iron chelate and nano-iron chelate, with concentration of 22.5 mg/L, was studied. This experiment was carried out in Research Greenhouse of Soilless Culture Research Center, Isfahan University of Technology, Iran, in the spring of 2013. Results showed that there were considerable positive and negative variations among wheat genotypes in response to application of nano-sized iron chelate fertilizer. Under the application of iron chelate, among the different measured traits, number of tillers and root/shoot ratio had the highest coefficient of variations, and the lowest values were observed for chlorophyll flourescence and green leaf surface. Under the application of nano-iron chelate, number of tillers and root/shoot ratio had the highest coefficient of variations, and the lowest value was observed for chlorophyll flourescence content. Nano-iron chelate fertilizer caused reduction of average dry matter yield of shoots, leaf area and root volume by 14.1, 9.5 and 8.9 percent, respectively, and increased root/shoot ratio by 13.7% for some wheat varieties, in comparison with the ordinary iron chelate. In response to nano-iron chelate fertilizer, compared to ordinary iron chelate, Line-9-shoory produced the highest total dry matter (14.49% increase) and Star variety had the lowest total dry matter (-51.82%).

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The required water for greenhouses in Kishestan, Soume-e-Sara town, Guilan province, Iran, is mainly provided by underground resources that have inappropriate quality. One way to reduce the impact of salinity an plant growth is proper nutrition. This greenhouse research was conducted to evaluate the effect of water salinity and foliar spray of calcium (Ca) and silicon (Si) on growth and vase life of gerbera in a factorial experiment based on compeletly randomized design with two factors. The first factor was salinity of irrigation water at two levels (0 and 1.5 dS/m) and the second factor was foliar spray at seven levels (without spray, twice Ca spray, four times Ca spray, two times Ca spray + once Si spray, twice Ca spray + twice Si spray, four times Ca spray + once Si spray, and four times Ca spray + twice Si spray), each with three replications. Results showed that four times Ca foliar spray led to an increase in stem hight, stem and neck diameter, postharvest life and Ca concentration of shoots. In all spray treatments, number of flowers in zero salinity was more than 1.5 dS/m treatments. In general, in case of using low-quality water (electrical conductivity of 1.5 dS/m), the effects of salinity on dry and fresh weights of gerbera plant and vase life of its flowers can be reduced by foliar application of Ca and Si. Since inappropriate water quality in Rasht Greenhouse Complex, Soume-e-Sara town, is one of the main problems of the farmers, especially in growing the ornamental plants, effects of salinity on plant growth could be alleviated with foliar spray of nutrients, especially Ca and Si. In this respect, four times spray of Ca and also twice spray of Ca + twice spray of Si are recommended.

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In greenhouse culture, in addition to increasing the quantity and quality of crop production in comparison with traditional methods, the agricultural inputs are saved, too. Recently, using new methods, designs and materials, and higher automation in greenhouses, better management has become possible for enhancing yield and improving the quality of greenhouse crops. The constructed and evaluated central controller unit (CCU) is a central controller system and computerized monitoring unit for greenhouse application. Several sensors, one CCU, several operators, and a data-collection and recorder unit were the major components of this system. The operators included heating, cooling, spraying, ventilation and lighting systems, and the sensors are for temperature, humidity, carbon dioxide, oxygen and light in inside and outside the greenhouse. Environmental conditions were measured by the accurate sensors and transmitted to the CCU. Based on this information, the CCU changed variables to optimize the greenhouse environmental conditions to predetermined ranges. This system was totally made of local instruments and parts and had the ability to integrate with the needs of the client. The designed and implemented CCU was tested in a greenhouse located in Agriculture and Natural Resources Research Center of Khuzestan Province during summer season of 2011. The CCU was operated successfully for controlling greenhouse temperature in the range of 22-29 ˚C, relative humidity of 35-55%, artificial lighting in the case of receiving radiation of less than 800 Lux and turning on the ventilation units if the concentration of carbon dioxide was more than 800 mg/L.

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Soil salinity and compaction are probably the most prevailed limitations for crop growth and production. Their mitigation and control may be important crop management keys that can ensure yield sustainability and optimum use of land and water. This research was performed to investigate the combined effect of soil salinity and soil compaction on some growth characteristics of corn (Zea mays L.) root. For this purpose, a factorial pot experiment on the basis of completely randomized blocks design with three replications was performed. The experimental factors were three levels of soil salinity (electrical conductivity of saturated paste extract of 1.5, 2.5 and 4.5 dS/m) and three levels of soil compaction (bulk density of 1.3, 1.55 and 1.75 g/cm³). For salinity treatments, different amounts of NaCl was dissolved in the required volume of distilled water to have soil water content to 16% and then were added to the soil. For soil compaction treatments, a 4.5 kg solid cylinder was allowed to fall freely from 45 cm height over the soil surface in the pots. During the 3 months of experimental period, the pots were irrigated with distilled water through regular weighing. Results showed that the main effects of soil salinity and compaction at 1% probability level and their combined effects at 5% probability level led to significant reduction in root dry weight, root volume, root length, root mean diameter and ratio of root weight to soil weight. Combined effects of soil salinity and compaction reduced growth characteristics of the corn roots 20% more than their individual effect. Therefore, it can be concluded that soil salinity and compaction intensify their negative effects and suppress growth and development of corn roots.

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Fragrant tuberose is the most important scented cut flower of Iran, which rank 4^th among other cut flowers, based on the cultivation area and production. Due to the scarcity of water resources, soil constraints, and the aim of comparison and possible substitution of soil cultivation with soilless cultivation of tuberose, a pot experiment was conducted as factorial, based on completely randomized design with four replications, on two cultivars of tuberose (‘Mahallati’ and ‘Dezfuli’), in two greenhouse production systems, with soil and soilless medium. Based on the ANOVA results, photosynthetic capacity [number of leaves and leaf area, stomatal conductance and photosynthetic pigments content (chlorophyll a, b and total)], flower-stem height, number of florets, diameter of florets, nutrients uptake and flower vase life were significantly (P≤0.01) affected by culture system. Soilless system increased the flower-stem height and vase life (as the main quality indices of cut flowers) by 50% and 35%, respectively, as compared with soil cultivation. In addition, peroxidase activity, calcium, and potassium uptake were significantly (P≤0.05) affected by cultivar. Analysis of variance indicated that interaction of cultivar and cultivation system had significant effects on calcium uptake and number of leaves per plant. According to the results, soilless culture improved photosynthetic capacity and mineral uptake and subsequently increased quality and vase life of cut tuberose. This culture system showed high ability and potential to replace soil cultivation of tuberose.

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Calcareous soils with high pH in Jiroft region have caused difficulties in uptake of micronutrients, particularly iron (Fe), by strawberry plant.  In the present greenhouse research, treatments consist of combination of different sources, application method and amount of iron application. Results showed that soil application of 10.5 kg/ha chelated iron (Fe-EDDHA) had the highest fruit yield, average fruit weight and vitamin C content. Based on the orthogonal comparison, in general, applying iron with any method of application and combination significantly affected most of the measured plant traits (with the exception of fruit acidity and vitamin C content). Therefore, regardless of the type and method of iron application, its application is necessary to increase yield and other quality parameters of the strawberry under greenhouses conditions in Jiroft region. Economic evaluation of the treatments showed that spraying iron sulfate and Fe-HEEDTA is not economically justified due to the costs imposed on greenhouse owner. Generally, soil application of Sequestrene-138-Fe is economically valuable, compared with spraying of iron sulfate and Fe-HEEDTA. Using 4.5 kg/ha Sequestrene-138-Fe has higher economic justification and higher profitability rate (1979.95% in comparison with 1345 and 1176.89%, respectively) compared to 7.5 and 10.5 kg/ha. Thus, soil application of 4.5 kg/ha Sequestrene-138-Fe (Fe-EDDHA) for greenhouse production of strawberry in Jiroft region, which have similar conditions to the present experiment, is recommended.

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Iron is an essential element for plant growth which is involved in many plant processes such as photosynthesis and activating enzymes involved in mitochondrial and photosynthetic electron transfer. In order to compare the effect of different sources of iron on yield and physiological characteristics of two varieties of lettuce in hydroponic culture, a complete random factorial experiment was done in Nutrition Film Technique (NFT system). The factors involved cultivar in two levels (Leaf lettuce and head gardesco) and iron fertilizer in three levels (Ferrous sulfate, Fe-EDDHA and Nano Fe-chelate, all with the 20 micro-molar concentration). The results indicated that the maximum yield and physiological parameters (Fv/Fm, PI, soluble sugars, proline, chlorophyll a, b, total and carotenoids) were obtained for the treatment of Fe-EDDHA and leaf lettuce gardesco cultivars, but the highest absorption of nutrients (iron, copper, manganese, nitrogen and phosphorus) belonged to the treatment of Fe-EDDHA and head lettuce gardesco cultivar. According to the results, it is recommended to use Fe-EDDHA chelate to increase the yield of lettuce in hydroponic systems.

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In order to determine the best source of iron fertilizer for green pepper under alkaline conditions, the experiment was conducted as factorial with three factors include of iron fertilizer (control, Fe-EDDHA and nano iron chelate), sodium bicarbonate (0 and 10 mM) and two cultivars (Bonanza and Griffaton) with three replications. Plants were treated with bicarbonate 45 days after planting for 2 month. The results indicated that the maximum vegetative parameters (root and shoot fresh and dry weight), reproductive parameters (number of fruits, fruit length, fruit weight and fruit diameter) and physiological paramneters (RWC, PI and F_v/F_m) were found in control treatment. Under the alkaline condition maximum and the minimum chlorophyll a and b and carotenoid contents were obtained in control and Fe-EDDHA treatment, respectively. Sodium bicarbonate significantly decreased the Fe concentration in root and shoot of pepper. According the results obtained from this work, Fe-EDDHA was the best iron fertilizer under the alkaline conditions and nano chelate iron was next in this situation.

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Sunlight, as a natural resource, is an important factor in agriculture, which is supplied indefinitely and without any charge by the sun. But some phenomena such as cloudy weather or shortening the length of the day throughout the year, cause restrictions on access to this important source. This is very important for cultivation in controlled environments such as greenhouses, which usually produce off-season. This paper is aimed at evaluating the economic exposure of artificial lighting to increase cucumber production to compensate for the lack of light due to weather cloudiness. For this purpose, by using daily meteorological data of the study area and cucumber production from one of the greenhouses in Hamadan city, which didn’t have artificial lighting system, the damage of cloudy hours was assessed. Daily time series data were collected for the period of April 2007 to July 2010, and the amount of crop reduction per hour of cloudiness was estimated by using an autoregressive distributed lag model (ARDL). Results showed that on the average, in each production period, atmospheric cloudiness has 3.8% negative effect on greenhouse cucumber production. On the other hand, based on this research’s findings, compensating for the lack of sunlight due to atmospheric cloudiness by artificial lighting in this area isn’t economically feasible, and the benefit/cost ratio is 0.11

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In order to study the effect of zinc (Zn) nutrition on relative tolerance of olive (Olea europea L.) seedlings to salinity, a factorial pot experiment was conducted, based on completely randomized design with three replications, during fall 2013. One-year seedlings of two olive cultivars (‘Frontoio’ and ‘Conservolea’) were planted in 10-litre plastic pots containing sand and perlite (1:1 ratio) and treated with nutrient solutions having different levels of sodium chloride (0, 40, 80 and 120 mM) and Zn (0, 1 and 5 µM zinc sulfate). Results showed that salinity reduced root and leaf dry weight, seedling height, number of leaves, potassium/sodium (K/Na) ratio of roots and leaves, and calcium (Ca) molarity ratio in roots and leaves of both cultivars. With increasing Zn content to 5 µM, all the growth traits of the two cultivars were increased significantly. This trend was observed in the leaf K content and K/Na ratio of roots and leaves as well. Interaction of Zn×cultivar and salinity×cultivar was significant only on root dry weight. The Frontoio cultivar had maximum root dry weight at all salinity levels. The Zn had a positive and significant effect on root and leaf dry weight. Interactions of Zn×salinity and Zn×cultivar were not significant on leaf dry weight. Frontoio cultivar was more tolerant cultivar to salinity according to the maximum root and leaf dry weight, as well as other studied traits. Application of Zn not only raised growth indices, but also increased K absorption, K/Na ratio, and Ca molarity ratio. This role led to improved nutrition conditions and finally increased dry leaf and root weights. In general, Ca molarity ratio is more proper index in comparison with K/Na ratio to determine tolerance to salinity in the olive seedlings

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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.