Journal of Plant Process and Function

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1 Department of agronomy and plant breeding, College of Agricultural, Isfahan University of Techchnology, Iran *Corresponding Author: Abstract: The effects of salt stress on the activity of ascorbate peroxidase (APX), glutathione reductase (GR), superoxide dismutase (SOD) enzymes, carotenoid content, the rate of lipid peroxidation (LP) in term of thiobarbituric acid-reactive substances (TBARS) content and grain yield were investigated. Eighteen triticale lines comprising 9 doubled haploid (DH) lines and 9 their corresponding F8 lines as well as two bread wheat cultivars ('Roshan' as a drought tolerant and 'Kavir' as a salt tolerant cultivar), were used. A randomized complete block design with three replications was used for each environmental condition (non-stressed and salt-stressed conditions) at the Research Farm of College of Agriculture, Isfahan University of Technology in a silty clay loam soil in 2008-2009. Both salt stressed and non-stressed experiments were irrigated with water having EC of 1 dS m-1 until mid-jointing stage (43 growth stage of Zadoks scale), and afterward salt-stressed experiment was irrigated with saline water containing 175 mM NaCl and EC= 16 dS m-1. Salinity led to an increase in the enzymes activities and LP and decrease in carotenoid content in the leaves of both triticale and wheat genotypes. An inverse and significant relationship between grain yield loss due to salinity stress with carotenoid content was observed under salinity stress (r = -0.54*). Under both conditions, negative and significant correlations (r = -0.61**) were observed between grain yield and LP. The orthogonal comparison between triticale line and wheat cultivars revealed the superiority of triticale lines for the production of antioxidants and less LP in triticale than wheat under both environmental conditions, which may be related to the development of relatively higher salt tolerant in triticale.

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Atefeh Payez1, Faezeh Ghanati1*, Mehrdad Behmanesh1, Parviz Abdolmaleki1, Mina Ghahremaninezhad1 1*Faculty of Biological Sciense, Tarbiat Modares Univercity, Tehran (Received: 2 January 2012 Accepted: 4 May 2013) Abstract: Several studies have shown that magnetic fields can exert an influence on a large variety of cellular functions however, the exact mechanism of this interaction in living cells is still unclear. One possible explanation for the adverse effects of magnetic fields on living organisms is oxidative stress resulting from an increase in the production of reactive oxygen species through iron as a mediator. Oxidative stress also brings about changes in enzyme activity, gene expression, and the release of calcium from intracellular storage sites. In the present study the effects of 30 mT static magnetic field and a 10 KHz electromagnetic field on the root and shoot length, activity of antioxidant system, membrane integrity, and the total of calcium and iron content of wheat (Triticum aestivum L.) at vegetative stage were estimated. The results showed that magnetic field caused promotion of antioxidant system, maintenance of membrane integrity and changes in calcium and iron balance, compared to the control group. These effects vary depending on many factors e.g., the sort of magnetic field and the plant organs being exposed to the field.

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A field experiment was conducted to evaluate the interference effects of wild barley (Hordeum spontaneum L.) on wheat (Triticum aestivum L.) yield, in 2009. The effects of different densities of wild barley (0, 25, 50, 75, 100, 125 plants m-2) in interferences with wheat at density of 300 plants m-2 were studied in a completely block design with three replications. Results showed that with increase in wild barley density, wheat yield decreased linearly and H. spontaneum at highest density treatment caused 24% yield loss in wheat. Also a significant decrease was observed in 1000- grain weight, leaf area index, crop growth rate and relative growth rate of wheat. However wheat height, seed number in spike and net assimilation rate of wheat was not affected by weed interference. Results clearly showed that Hordeum sponstaneum in high density can reduce growth and yield of wheat under irrigation condition in dry land regions.

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In recent decades, the increasing trend of concurrent soil salinity and heavy metal stresses in arid and semi-arid regions all over the world has become a serious threat for agricultural production and human food security. Cadmium (Cd), as a heavy metal, can be readily absorbed by plant roots, leading to disruptions in plant physiological and biochemical activities. A factorial pot experiment was carried out based on a completely randomized design with the aim of investigating the beneficial effects of root symbiosis with mycorrhizal fungi and azotobacter on the responses of two bread wheat (Roshan and Bahar) and two durum wheat (Yavarus and Behrang) cultivars grown in a naturally Cd-contaminated soil to salinity stress. Experimental factors were consisted of (1) irrigation water salinity in three levels including 0, 75 and 150 mM NaCl and (2) inoculation treatments in four levels including no-inoculation as control, plus separate inoculation by Rhizophagus intraradices and Funneliformis mosseae mycorrhizal fungi and Azotobacter sp. bacteria. Salinity stress was observed to cause an increase in shoot Cd concentration, antioxidant enzymes activity and the levels of proline, hydrogen peroxide and malondialdehyde, while it decreased shoot dry weight. Under saline condition, the salt tolerant cultivars (Roshan and Behrang) showed a lower increase rate of shoot Cd concentration as compared to salt sensitive cultivars (Bahar and Yavarus), while they showed a higher increase rate of antioxidant enzymes and proline content. Wheat plants inoculated by F. mosseae, Rh. intraradices and Azotobacter sp. revealed a higher shoot dry weight (20, 12 and 7%, respectively) as well as higher activities of catalase (22, 18 and 12%), peroxidase (39, 32 and 20%) and ascorbate peroxidase (64, 56 and 47%) antioxidant enzymes, while a lower shoot Cd concentration (24, 11 and 5%) and lipid peroxidation activity (14, 10 an 5%) as compared to non-inoculated plants. The results from this experiment showed that soil salinization increased cadmium concentration in wheat plants but the inoculation by mycorrhiza and rizobacter stimulated antioxidant enzyme defense system and reduced lipid peroxidation and cadmium absorption from soil.

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In order to investigate the effect of plant density and foliar application of kaolin on rainfed wheat cultivars, a factorial-split plot study was conducted in a RCBD with four replications under rainfed conditions in Koohdasht. Plant density factor viz. 350, 500, 650 and 800 plants per square meter and cultivar factor including three dryland wheat cultivars Karim, Kuhdasht and Qaboos as factorial in main plots and kaolin foliar application in two levels of non-application and application of Kaolin were placed in sub-plots. The results showed that with increasing plant density, the amount of polyphenol oxidase and peroxidase antioxidants (26.2% and 9.1%, respectively) as well as grain carbohydrates (11.9%) increased, whereas the amount of grain protein (4.3%) decreased, at the highest density compared to the control. The amount of nitrogen, potassium and iron in the grain decreased with increasing plant density. The highest amount of phosphorus, zinc and grain protein belonged to Qaboos cultivar, so that in Qaboos cultivar the amount of phosphorus was 6.4% and 1.9%, respectively, at the same time, the amount of zinc was 4.6% and 1.3%, respectively, and the amount of protein was 2.5% and 0.3%, respectively, more than Karim and Kuhdasht cultivars. Foliar application of kaolin increased the uptake of all essential elements studied in the shoot and the amount of nitrogen, phosphorus, iron, zinc and carbohydrates in the grain; but reduced the antioxidants of the shoot and the amount of potassium and protein in the grain compared to the non-use of kaolin. In total, Qaboos cultivar at a density of 500 plants per square meter with the use of kaolin was recommended as the best treatment for grain production and enrichment at Kuhdasht region.