Aria Dolatabadian

Zeolite influences on nitrate leaching, nitrogen-use efficiency, yield and yield components of canola in sandy soil

With regard to the low cation-exchange capacity and large saturated hydraulic conductivity of sandy soils, a field experiment was carried out in 2006–2007 to determine the impact of zeolite on nitrogen leaching and canola production. Four nitrogen (N) rates (0, 90, 180, and 270 kg ha–1) and three zeolite amounts (3, 6 and 9 t ha−1) were included as treatments. The results demonstrated that the highest growth parameters and seed yield were attained with 270 kg N ha−1 and 9 t zeolite ha−1. However, the highest and the lowest seed protein percentage and oil content were obtained with 270 kg N ha−1 accompanied by 9 t zeolite ha−1, respectively. Nitrate concentration in drained water was affected by nitrogen and zeolite. The lowest and highest leached nitrate values were found in control without N and zeolite (N0Z0) and in treatments with the highest N supply without zeolite (N270Z0), respectively. In general, nitrogen-use efficiency decreased with an increase in N supply. Application of 9 t zeolite ha−1 showed higher nitrogen use efficiency than other zeolite amounts. Also, application of more N fertilizer in soil reduced nitrogen uptake efficiency. In total, application of 270 kg N ha−1 and 9 t zeolite ha−1 could be suggested as superior treatment.

The role of calcium in improving photosynthesis and related physiological and biochemical attributes of spring wheat subjected to simulated acid rain

The response of photosynthesis parameters, catalase, superoxide dismutase and peroxidase activity, malondialdehyde, proline, chlorophyll, yield and yield components to foliar application of calcium and simulated acid rain in wheat were investigated. Foliar treatment of calcium led to significant increases in the photosynthesis rate, transpiration rate, stomatal conductance, proline, chlorophyll, yield and yield components in plants subjected to acid rain. Antioxidant enzyme activity and lipid peroxidation in the wheat leaves decreased because of calcium foliar application. Calcium hindered degradation of the rubisco subunits under acid rain treatment compared with water-treated plants. Results suggest that acid rain induces the production of free radicals resulting in lipid peroxidation of the cell membrane so that significant increase in antioxidant enzyme activity was observed. In addition, photosynthetic parameters i.e. photosynthesis rate, transpiration rate and stomatal conductance were drastically suppressed by acid rain. The cellular damage caused by free radicals might be reduced or prevented by a protective metabolism including antioxidative enzymes and calcium. We report that foliar application of calcium before acid rain may ameliorate the adverse effects of acid rain in wheat plants.

Effect of salicylic acid and salt on wheat seed germination.

Abstract The effects of pretreatment with salicylic acid on wheat seed germination (Triticum aestivum L. cv. Roshan), lipid peroxidation, and superoxide dismutase, catalase, polyphenol oxidase, and peroxidase activity were studied under conditions of salt stress. Seeds treated with different concentrations of salicylic acid were used for measuring germination traits. Salt stress was induced by sodium chloride solution. Seeds were soaked in salicylic acid solution for 24 h, dried with sterile paper, transferred to sterile Petri dishes, and treated with 10 ml NaCl solution at different concentrations. After 1 week, the number of germinated seeds, root length, seedling length, and dry weight were recorded. Antioxidant enzyme activity and lipid peroxidation were also assayed. Salinity decreased seed germination. Thus, a high concentration of NaCl (200 mM) decreased germination by 17.6% compared with control treatment. Salicylic acid significantly increased germination in stressed and control seeds. Salicylic acid increased the level of cell division of seedlings and roots, which increased plant growth. Salt stress significantly increased the activity of the antioxidative enzymes catalase, superoxide dismutase, peroxidase, and polyphenol oxidase in wheat seedlings, and salicylic acid reduced the activity of antioxidant enzymes as stress signal molecules. Our results indicated that scavenging of reactive oxygen species was effective, especially by salicylic acid, and that membrane damage was limited. The aim of the present work was to study the character of changes in enzymatic systems induced by NaCl and salicylic acid in wheat seedlings under conditions of salt stress. In brief, salicylic acid treatment reduced the damaging action of salinity on embryo growth and accelerated a restoration of growth processes; thereupon it may be effective for the improvement of seed germination in arid and semi-arid regions.

How Organic and Chemical Nitrogen Fertilizers, Zeolite, and Combinations Influence Wheat Yield and Grain Mineral Content

Nitrate leaching from agricultural soils represents substantial losses of N from fertilizer. Nitrogen leaching in sandy soil decreases fertilizer efficiency and can depress crop production. Materials with high cation-exchange capacity are hypothesized to reduce N leaching and increase N uptake in sandy soils. This randomized complete-block design study evaluated the influence of chemical, organic, and integrated fertilizer treatments and natural zeolite on growth, yield, and grain mineral content of wheat (Triticum aestivum L.) grown on sandy soils. Supply of N by urea and composted cattle manure amended with 10% (w/w) zeolite increased wheat growth, yield, and yield components. Similar results were obtained when zeolite was applied directly to soil. The highest grain Zn, Fe, and Mn contents were achieved in plots treated only with organic fertilizers. Chemical plots produced the highest N and protein content. Integrated fertilizer treatments amended with zeolite are an effective and environmentally sound method to improve wheat yield.

Influence of Diazotrophic Bacteria on Antioxidant Enzymes and Some Biochemical Characteristics of Soybean Subjected to Water Stress

Abstract Drought stress is an abiotic stress that imposes serious constraints on plants. The present investigation was carried out to determine the inter-relationship between some physiological attributes of soybeans affected by drought stress and pure isolates of Azotobacter and Azospirillum. Drought stress and bacterial application increased catalase and glutathione peroxidase activity, whereas drought stress increased superoxide dismutase activity during the pod-filling stage. Abscisic acid and proline levels increased due to drought stress and bacterial application during the flowering stage, whereas total plant nitrogen was enhanced under well-watered conditions when plants were inoculated with bacteria. The close relationship between enzyme activity and drought stress with bacteria indicated that antioxidant enzymes play an important role in alleviating the detrimental effects of water stress. In addition, the enhancement of abscisic acid and proline could be positively linked with drought stress, and drought-induced abscisic acid could induce proline accumulation and the expression of antioxidant enzyme genes.

Morphological and Physiological Characters of Aloe vera Subjected to Saline Water Irrigation

Aloe vera is grown in arid climates where salinity can limit plant growth and development. A study was conducted to examine the morphological and physiological characters under salt stress. Plants were cultivated in pots and irrigated with freshwater (EC 450 μs cm−1) or saline lake water (EC 3, 6, 9, 12, 15, 18, or 21 dS m−1). Results indicated that salinity influenced the plant growth and morphological traits and the biomass. Glucose, xylose, and mannose concentrations in leaf gel increased with increasing salinity up to 9 dS m−1 and decreased with higher saline concentrations. Aloin concentration increased with salt stress up to 15 dS m−1 that decreased at higher salinity concentrations.

Chitosan Improves Osmotic Potential Tolerance in Safflower (Carthamus tinctorius L.) Seedlings

Salinity and water-deficit stress reduce yield in agricultural crops. On the other hand, seed germination is critical in seedling establishment and subsequent plant growth. Therefore, the present investigation was carried out to evaluate the effects of chitosan (Ch) concentrations (0% [control], 0.05%, 0.1%, 0.2%, 0.4%, 0.5%, 1%, 2%, and 3%) on the tolerance of safflower (Carthamus tinctorius L.) to different osmotic potentials (0, −0.4, −0.8, and −1.2 MPa). Induced osmotic potential significantly decreased germination percentage, germination index and rate, length and weight of root and shoot, and protein content. Proline content, malondialdehyde content (MDA), and catalase (CAT) and peroxidase (POX) activity increased when osmotic potential was increased to −0.8 MPa. Under unstressed conditions (0 MPa), there were no significant differences in germination percentage among different concentrations of chitosan, whereas MDA content, CAT, and POX activity were increased by low concentrations of chitosan (0.05%–0.4%). With increasing water-deficit stress, low concentrations of chitosan increased germination percentage but decreased MDA and proline contents and CAT and POX activity. Thus, it could be concluded that low concentrations of chitosan exhibited positive effects on water-deficit alleviation through the reduction of enzyme activity. Therefore, chitosan should be an effective biostimulator to enhance seedling growth and plant tolerance to oxidative stress conditions, especially under conditions of drought stress.

Integrated fertilizer management to attain sunflower sustainable production under different irrigation regimes

Nitrogen release studies are of considerable interest in soil and environmental science. The objective of this research was to study integrated fertilizer management for the reduction of nitrogen leaching in sandy soils. An experiment was conducted during 2005–2006 to evaluate the effect of integration of zeolite, manure and urea on some traits of sunflower under different irrigation regimes. The results demonstrated that different irrigation regimes had significant effects on seed yield and yield component, final dry matter, chlorophyll content, leaf area index (LAI) and oil yield. But elements concentration in leaf and seed were not affected by irrigation regimes. Also it was observed that seed yield, oil yield, capitulum diameter, percentage protein, chlorophyll content, final dry matter, yield component, nitrogen concentration of leaf and seed, LAI and water use efficiency (WUE) were affected significantly by manure treatments. Interaction effects were significant on some traits. Finally, regarding the results of this experiment and the significant effect of the application of zeolite, the best treatment is suggested as the supply of 80 kg ha−1 N by urea and 50 kg ha−1 N by manure in combination with 15% of total manure weight zeolite, under the first irrigation regime.

Influence of root-zone temperature on growth and nitrogen fixation in three Iranian grasspea landraces

Abstract In order to study the effects of different root-zone temperature (RZT) and two Rhizobium leguminosarum strains (originating from cold area and temperate area) on some grasspea (Lathyrus sativus) landraces (Ardabil, Shahrekord, and Zanjan) of Iran, an experiment was conducted in a controlled-environment chamber. In this experiment, four root-zone temperatures (5, 10, 15, and 25°C) and a constant air temperature were considered. Results showed that there were differences among the grasspea landraces for nodulation and nitrogen fixation, growth and development, and dry matter. Low RZT reduced growth, nodulation, and nitrogen fixation in grasspea landraces. Strains had different effects on landraces. Inoculated plants with strain originating from cold areas produced the most nodule number, and plant nitrogen concentration at 15°C RZT, whereas inoculated plants with strain originating from temperate area produced the most nodule number, and plant nitrogen concentration at 25°C RZT. Nodulation, nitrogen fixation, and nitrogenase activities of inoculated plants with a strain originating from cold areas in inoculated plants were higher at low temperature than in inoculated plants with a strain originating from temperate areas. This experiment also showed that grasspea production is not likely to be successful when RZT is below 10°C, especially during vegetative development. Therefore, in the zones where soil temperature is greater than 10°C RZT, grasspea landraces have normal growth and produce average yields.