Journal of Soil and Plant Interactions

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This experiment was conducted to determine the effect of salinity and nitrogen on growth and yield of tomato and concentration and total uptake of some nutrients in different parts of plant in hydroponics culture. Nitrogen (N) was used at 0, 1.5 and 3% levels as NH4Cl and NH4H2PO4 and salinity consisted of 0, 30 and 60 mM as NaCl and CaCl2 (2:1 w/w). A completely randomized design experiment was carried out under greenhouse conditions. Results showed that fruit fresh weight increased with N application but salinity treatment decreased fruit yield. Maximum fresh weight was observed in treatment with 3% N and without any salinity application, whereas minimum fresh weight was obtained with 30 mM salinity and without any N application. Application of 30 and 60 mM salinity increased fruit phosphorous concentration significantly (P<0.05), but it did not affect shoot and fruit concentration. Nitrogen application increased fruit, shoot and root phosphorous concentration significantly. Root, shoot and fruit N uptake increased with N application (without salinity) whereas at high salinity level, increase in N uptake was lower than at low salinity level. Salinity increase without N decreased fruit phosphorous and manganese uptake, root copper, zinc and manganese concentration and shoot manganese uptake. Furthermore, results showed that at low salinity level, N application can alleviate the negative effects of salinity on growth and yield of plant.

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Salinity plays an important role in the reduction of tomato growth, especially in arid and semi-arid regions. Nitrogen (N) may increase tomato tolerance to salt stress by increasing plant growth. In order to investigate the interaction effect of salinity and nitrogen on tomato growth, fruit quality, and micronutrient concentration in tomato plants, a hydroponic experiment was conducted in a completely randomized design with three replications. Treatments included 3 salinity levels (0, 30 and 60 mM), and 3 nitrogen rates (0, 1.5, and 3 mM). Results indicated that salinity decreased tomato height, shoot and fruit fresh weight, and increased citric acid in tomato fruit and consequently caused blossom-end rot in tomato fruit. However, salinity improved fruit quality (flavor). The use of N increased plant height, shoot, and fruit fresh weight compared to control. By application of N to saline nutrient solution, plant height increased. Salinity increased concentration of iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) in roots, as`well as Fe and Cu in fruit. Increasing N rates in nutrient solution increased micronutrients concentration in tomato roots. Interaction of 60 mM salinity and N decreased micronutrients concentration in root, compared to control. Our tentative conclusion shows that the addition of N to the nutrient solution may decrease detrimental effect of salinity on the growth of tomato plants.

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The effect of salinity and nitrogen on yield, vitamin C, citric acid and nutrient distribution of tomato in hydroponics culture was investigated. Tomato seeds were first let germinate in yonolit pots with wet coco peat and then their seedlings were transferred to plastic tanks containing 5 liters nutrient solution. Treatments were three levels of salinity (0, 30 and 60 mM as NaCl and CaCl2) and three levels of nitrogen (0, 1.5 and 3% as NH4Cl and NH4H2PO4 and 2:1 w/w). The results showed that nitrogen application increased wet and dry weights but salinity decreased them. Furthermore, salinity application had no effect on vitamin C, but 60 mM salinity increased citric acid compared to that of control. Nutrients distribution varied in different parts of then plants. Salinity increased iron and manganese uptake, but it had no effect on uptake of other nutrients. Salinity and nitrogen application reduced this inappropriate effect.

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To determine the effect of application of phosphorus (P) and organic matter on soil-plant P relationship at different growth stages of spinach, an experiment was conducted at greenhouse conditions. Treatments consisted of two levels of organic matter (0 and 2% of sheep manure) and three levels of P as Ca(H2PO4)2 (0, 20 and 60 mg P kg-1soil). Soil and plant samples were collected at five growth stages (the first sampling was in the fourth week after emergence, and the other samplings were each one week after the first sampling). The results showed that crop yield increased with the increase of soil P at all growth stages, whereas it had no significant effect on plant P content. In the 4th week of growth, plant P increased with an increase of soil P, and it remained relatively unchanged in the 5th week. But it decreased significantly in the 6th to 8th week. Concentration of plant nutrients depends not only on soil nutrients concentration but also on plant age and availability of other nutrients. In some stages of the plant growth, the growth rate might be too fast such that total uptake of the nutrients is not enough to maintain the necessary concentration. Plants required adequate P at early growth stages for optimum growth. Phosphorus uptake was increased with plant growth in all samples. Soil P content was higher in all organic matter treatments (especially in the 6th week after emergence). Phosphorus uptake in samples with organic matter, and no addition of P, was more than the samples which received P. This might be due to mineralization of organic P added to the soil.

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A greenhouse experiment, as hydroponic, was carried out in order to investigate the response of sunflower genotypes (Hison125, Iroflor and Bliezer) to different levels of salinity (0, 60 and 120 mM of NaCl) and Fe (0, 50 and 100 mM) in nutrient solution. The experiment was arranged as factorial, based on a completely randomized blocks design with four replications. Results showed that plant height, leaf area, shoot and root dry weight, ratio of shoot/root dry weight, K concentration, the ratio of K/Na concentration in shoot and roots were reduced and the concentration of Na was increased as the level of salinity was increased in the nutrient solution. There was a significant increase in the values of plant height, leaf area, shoot dry weight and the ratio of shoot/root dry weight as the level of Fe in the nutrient solution was enhanced from 5 to 50 mM. However, with a further increase from 50 to 100 mM, there appeared no significant changes in the amount of these traits. The interaction between genotype and Fe level was significant on the root dry weight and K concentration in the leaves. The lowest and the highest increase in root dry weight, in response to increased level of Fe, was observed in Hison125 and Bliezer cultivars, respectively. However, the difference between cultivars became less in treatments containing higher levels of Fe in the nutrient solution. Considering the K concentration in leaves, only Bliezer cultivar showed positive response to increasing Fe level. The interaction between salinity, genotype and Fe level was significant on the concentration of Fe in plant. Based on the results, increasing Fe concentration in the nutrient solution improves sunflower growth. However, the increased concentration of Fe could not significantly alleviate the negative effects of salinity.

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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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In order to study the response of rice genotypes to different levels of nitrogen (N), an experiment was conducted to evaluate growth and development of 28 selected rice genotypes (improved and local from north of Iran, and cultivated in Central Iran) under two levels of N including 2.85 mM (N concentration of Yoshida solution) and 1.42 mM (half the N concentration of Yoshida solution) from ammonium nitrate source. The experiment was arranged as factorial, based on a completely randomized blocks design, with three replications. Results showed that the effects of genotype, N level and their interaction were significant on the number of tillers, leaf area, SPAD index, dry weight of roots, shoot and total, shoot and root length and biomass. The extent of reductions in the values of all measured traits, except for root length and dry weight, were higher in north local genotypes as compared to other tested groups. The reductions in total dry weight were 14.82, 5.80 and 2.67 percent for north local, north improved and genotypes from center of Iran, respectively. There was significant variation among genotypes in response to nitrogen deficiency. Nitrogen efficiency was highest in Fajr and Khazar within north improved genotypes, in Hassani and Kazemi within north local genotypes and in Line2 Firozan within genotypes from center of Iran. However, the lowest values for nitrogen efficiency were achieved in Nemat and Shirodi within north improved genotypes, in Tarom-mantaghe and Ahlami Tarom within north local genotypes and in Zayandehrud within genotypes from center of Iran. Results showed that correlation between shoot dry weight (as plant yield) with number of tillers and plant leaf area were higher under N deficiency (r= 0.74 and r= 0.57) than under nitrogen sufficiency (r = 0.13 and r = 0.41) conditions.

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This pot experiment was conducted to investigate the effects of ordinary and nano forms of zinc oxide on growth and ion content of four wheat cultivars (Niknejad, Iniya, Rowshan and Moghan2) under three salinity levels (0, 75 and 150 mM NaCl). In this experiment, shoot and root dry weight, and concentration of potassium, sodium and zinc in shoots were measured. Results showed that with an increase in salinity level, the shoot and root dry weight and concentration of potassium and zinc in shoot was decreased, but shoot/root dry weight ratio, sodium concentration and sodium/potassium ratio in shoots were increased. Plants provided with nano zinc oxide had higher concentration of zinc, as compared to the ordinary form of zinc oxide. Significant reduction of sodium/potassium ratio in shoots occurred due to plant nutrition of nano zinc oxide. As a result of application of nano zinc oxide, shoot dry weight was increased in Niknejad and Iniya wheat cultivars, but it was decreased in Rowshan and Moghan2 cultivars. The results of this experiment showed that there was significant variation among wheat cultivars in response to the application of nano zinc oxide.

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An experiment was conducted to determine the responses of 27 Iranian local and improved rice genotypes to two salinity levels (0 and 100 Mm NaCl) at Soilless Culture Research Center of Isfahan University of Technology. The treatments were arranged as factorial in a completely randomized design with three replications. The results showed that there was considerable variation in agro-morphological characters among Iranian rice genotypes under saline and non-saline conditions. A great variation in salt tolerance was observed among local genotypes of north, improved genotypes of north and local genotypes of center of Iran. Root growth was more sensitive to salt stress than shoot growth and responds more quickly to the stress. The salt-tolerant rice genotypes had more green leaf area duration as a major factor for salinity tolerance. Average total biomass of local genotypes of north, improved genotypes of north and local genotypes of center of Iran under non-saline conditions were 0.94, 1.09 and 1.38 and under saline conditions were 0.46, 0.59 and 0.58 g/plant, respectively. The highest and lowest tolerance to 100 mM NaCl salinity among local genotypes of north were observed in Daylamani and Domsorkh, among improved genotypes of north in Neda and Shiroodi, and among local genotypes of center of Iran in Jozdan and Zayandehrood, respectively. The genetic variation for salinity tolerance in Iranian rice genotypes may improve salt tolerance and increase rice production under saline conditions.

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One of the most important limiting factors in cultivation of strawberry in greenhouses during winter season is short day-length. An experiment was conducted to evaluate the effect of end-of-day red light on growth characteristics, yield and fruit quality of strawberry (cv. Queen Elisa) in a completely randomized design with 4 treatments in winter of 2013. Strawberry plants were exposed to red light (660 nm, 12 µmol/m.s) for 2, 4 and 8 hours, using LED light source, from 6 pm, and were compared with control (plants without red light treatment). Results showed that 8 hours of red light radiation caused a significant increase in number of leaves, petiole length, leaf length and width and leaf area of the plants. Fresh and dry weight of plants, as well as weight and length of Queen Elisa strawberry fruits were increased in red-light treatments. Also, soluble-solids content of fruits in radiated treatments, especially in 8 hours red light treatment, was increased. But, fruit’s titratable acidity and pH were not significantly affected by the red light. Results clearly demonstrated that end-of-day red light, emitted from LED source, improved morphological characteristics, growth, yield and fruit quality of strawberry cv. Queen Elisa.

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