Journal of Soil and Plant Interactions

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In order to assess the effect of salinity on root traits and yield of two wheat cultivars, an experiment was conducted in Agricultural, Medical and Industrial Research School, Nuclear Science and Technology Research Institute, Karaj, Iran, using factorial experiment based on complete randomized design with 3 replications. The first factor included sensitive wheat cv. (Tajan) and tolerant cv. (Bam) and the second factor was salinity stress at four levels (6, 8, 10 and 12 dS/ m). In each treatment, 10 days after anthesis, the variation of root dry weight, shoot dry weight, root/stem ratio, and root area and volume were analyzed. The results showed significant reduction (P≤0.01) in root dry weight, root area and root volume per plant. Root/shoot dry weight ratio decreased 35.1% and 8.2% in Tajan and Bam cultivars, respectively, at 8 dS/m compared to 6 dS/m. Results revealed that grain yield per plant was affected by root dry weight, as the highest grain yield was observed in Bam cultivar. Increased grain yield in this cultivar was due to higher root dry weight. Also, Tajan cultivar had the lowest grain yield and root dry weight in 12 dS/m treatment. There were positive correlations among root surface and volume with root dry weight and therefore with grain yield. Therefore, based on the parameters studied in this experiment, it can be stated that a large part of the traits associated with sensitivity or tolerance of wheat cultivars to salinity could be attributed to their roots’ characteristics.

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To alleviate water scarcity problem in arid and semiarid regions of Iran, different irrigation methods such as deficit irrigation, pressurized irrigation and partial rootzone drying (PRD) method have been suggested. In PRD method, half of the rootzone is watered and the other half is kept dry intermittently. The objective of this research was to study yield, yield components and water use efficiency (WUE) of tomato, using PRD irrigation method and a growth stabilizer in two soil textures, under greenhouse conditions. The factorial experiment, based on complete randomizal design and three replications, included three irrigation managements (T1, full irrigation T2, 50% of full irrigation, with PRD method and barrier T3, 50% of full irrigation, with PRD method and no barrier), two levels of stabilizer (B1, spraying sodium salicylate and B2, without spraying sodium salicylate) and two soil textures (S1, clay loam and S2, sandy loam). Results showed that the highest plants (176.2 cm) were in T1 treatment and the shortest plants (131.3 cm) were in T3 treatment. With 50% reduction of water in T2 compared to T1 treatment, number of flower stems was decreased by 15.2%. The highest and the least biomass and fruit yield were measured in T1 (506.8 and 342.5 g per plant) and T3 (126.2 and 54.8 g per plant) treatments, respectively. WUE was increased by 9.9% (changing from T1 to T2) and was decreased by 71.4% (changing from T2 to T3). The highest and the least fruit yield (216.7 and 174.4 g per plant) were obtained in S2 and S1 soils, respectively. Sandy loam soil with production of 7.22 kg/m3 had higher WUE than clay loam soil, which produced 5.38 kg/m3. Application of stabilizer increased fruit yield by 16% and WUE by 16.86%. In general, the effect of PRD irrigation method (with barrier) and spraying sodium salicylate on reducing water use and increasing productivity in greenhouse production of tomato was positive and recommendable.

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Micaceous minerals, including phlogopite, are frequently used as the growth medium with different commercial names for greenhouse plants. The objective of this investigation was to understand the effect of phlogopite size on the release and supply of potassium (K) under greenhouse conditions. A pot experiment was carried out with a completely randomized design using factorial arrangement and 3 replications. Treatments consisted of 4 particle sizes of phlogopite and a control, as well as 2 types of nutrient solution (with/without K). Alfalfa was the test plant which was grown on a mixture of sand and phlogopite for a period of 6 months. During the growing period, shoot was harvested 4 times and the root was collected at the end of the experiment and their K concentration was measured. Under the K-free nutrient solution, the K concentration and total uptake was highest in pots containing the smallest phlogopite size. As the size of mineral decreases, the conditions for mineral weathering seem to become more favorable and therefore, mica releases its K more quickly. Therefore, if the long term K supply is important, coarse-sized phlogopite should be used. In contrast, fine-grained phlogopite is suitable when K is to be supplied very quickly.

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A greenhouse experiment was conducted to evaluate the effect of vermicompost and sodium chloride (NaCl) on growth of spinach cv. Viroflay and some chemical properties of post-harvest soil. The greenhouse experiment was factorial, arranged in a completely randomized design with three replications. Treatments included three vermicompost levels (0, 1 and 2% w/w) and four salinity levels (0, 1, 2 and 3 gr NaCl/kg soil, equivalent to 0.7, 4.5, 8 and 11.5 dS/m, respectively). The highest relative yield of spinach shoots was obtained by application of 10% vermicompost, whereas, application of NaCl had no significant effect on relative yield of spinach shoots. Application of vermicompost increased mean leaf area and chlorophyll of shoots, organic matter (OM), electrical conductivity (EC), total nitrogen (N), available phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na) and chloride (Cl) of post-harvest soil. Addition of NaCl increased EC, P, K, Ca, Mg, Na and Cl of post-harvest soil, but had no significant effect on leaf area and chlorophyll content of shoots, OM and N of post-harvest soil. Addition of vermicompost had positive effect on spinach growth and plant nutrients availability in post-harvest soil. However, increased soil salinity, especially when high level of vermicompost is applied, should be considered. Application of NaCl, even up to the salinity of 11.5 dS/m, didn’t decrease significantly the spinach yield. Therefore, Viroflay cultivar could be introduced as a relatively resistant to salinity although, before any recommendations, it is needed to do further experiments, especially under field conditions, to confirm the results of this study

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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.

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Environmental stresses such as deficit irrigation and ultraviolet radiation can influence plant growth and development. Among the environmental variables, ultraviolet radiation is an important factor in plant response to other stresses, such as deficit irrigation. The purpose of this study was to investigate the effects of ultraviolet B radiation (UV-B), irrigation stress and combined effects of UV-B radiation and deficit irrigation on the morphological and biochemical responses of two basil species. Five treatments of UV-B radiation duration (0, 5, 10, 15 and 20 minutes per day) as well as four irrigation levels (100, 75, 50 and 30% of field capacity), two green and violet types of basil, based on a factorial experiment in a completely randomized design, were considered. Results indicated that the effects of duration of UV-B radiation, drought stress and basil type as well as their interaction on morphological and biochemical responses of both basil types were significant. At the highest level of UV-B radiation (i.e., 20 min/day), the measured traits such as photosynthetic pigments decreased by 18.2%, stem height by 11.2% and root length by 10.1% as compared to control, and the other traits such as leaf thickness increased significantly by 32.3%, malondialdehyde (MDA) content by 7.6%, anthocyanin by 40.6% and proline content by 19.1% as compared to control. While leaf area, number of leaves, root and shoot dry weights were firstly increased by radiation duration and then were reduced as compared to control. Five-minute irradiation treatment increased the stem dry weight (5.8%), leaf area (9.3%) and number of leaves (10.0%) as compared to the control. Deficit irrigation stress had 46.3% greater effect than UV-B radiation in reducing the measured basil characteristics. Simultaneous use of UV-B radiation and deficit irrigation prevented the reduction of growth factors due to low irrigation stress, indicating a synergistic state.

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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.

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Under water stress conditions, growth-promoting rhizobacteria could alter root characteristics, leading to increased plants yield. A controlled experiment with two barley cultivars, Dasht, and Kavir, was carried out with four inoculations of Bacillus simplex strains (31-2, 42-3, 51-4, and control), in two irrigation levels of 80 and 50% of field capacity. The results showed that inoculation with the mentioned bacteria increased the biological yield of barley by 28% under water stress condition compared to the control treatment. The effect of bacteria was cultivar dependent. B. simplex 31-2 had the most significant effect on the biological yield of Kavir cultivar, and B. simplex 42-3 on the Dasht cultivar. Linear relationships between root characteristics and barley's biological yield were observed. The highest coefficients of determination (R²) were obtained with fresh root weight (84%), root volume (83%), and root surface (81%). Considering the relationship between root traits and the biological yield of barley and the role of B. simplex 31-2 in a 121% increase in root area under water stress, it seems that this trait is the essential mediator of yield. Due to the insignificance effect of B. simplex 3-32 on the root characteristics, against the increase of shoot performance by this bacterium, its mode of action may be due to inducing improvement on other physiological pathways. Overall Bacillus bacteria are effective in mitigating the negative effect of water stress on barley and these bacteria can be considered effective candidates for the production of biofertilizers.
 

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Abstract
In some saline areas, pollutants such as heavy metals have been spread due to industrial activities. Halophyte plants can be useful for phytoremediation of such areas. To investigate the effect of salinity and heavy metal copper and their interaction effect on the halophyte plant Bassia scoparia L., two factorial experiments were conducted in a completely randomized design in hydroponics laboratory of Birjand University. In the first experiment, interaction effects of five levels of salinity (0, 100, 200, 300, and 400 mM) and five levels of copper (0, 50, 100, 200, and 300 mg/L) on the germination characteristics of B. scoparia seeds were measured. Results of this experiment showed that the increase in salinity and copper concentration had a significant negative effect on the germination and growth of seedlings. In the second experiment, the effects of three levels of salinity (0, 100, and 300 mM) and three levels of copper (0, 50, and 100 mg/L) on the traits related to growth and sodium and copper contents in root and shoot were investigated in pot culture. Salinity significantly increased the amount of sodium in root and shoot but did not affect the amount of copper in root and shoot. In the copper treated conditions, amount of this metal increased in root and shoot of B. scoparia. However, by having accumulation factors of less than one, B. scoparia does not seem suitable for plant extraction of copper, although it can be used to stabilize this metal by having a suitable biomass and considerable absorption of copper in root.

Background and Objective: One of the serious environmental pollutants is heavy metals, which have been rapidly increasing over the years due to industrial processes and human activities. Copper (Cu) is one of the heavy metals that causes toxicity in many plant species. Screening different plants is very important to know their capability for phytoremediation of heavy metals, especially under stressful environmental conditions such as salt stress. This research examines the phytoremediation capability of Bassia scoparia L. for copper under salt stress.

Methods: To investigate the effect of different levels of salinity and Cu and their interaction on B. scoparia, two factorial experiments were conducted in a completely randomized design with three replications. In the first experiment, the interaction effects of five levels of salinity (0, 100, 200, 300, and 400 mM NaCl) and five levels of Cu (0, 50, 100, 200, and 300 mg/L) on the germination characteristics of B. scoparia seeds were measured. In the second experiment, the effects of three levels of salinity (0, 100, and 300 mM) and three levels of Cu (0, 50, and 100 mg/L) on the lengths and dry weights of root and shoot, the amounts of chlorophyll a, b, and carotenoid, the amounts of Na and Cu in the root and shoot were investigated. After measuring the concentrations of Na and Cu in the roots and shoots, the accumulation coefficients of these elements, including bioconcentration factor (BCF), accumulation factor (AF), and translocation factor (AF) were also calculated.

Results: The results of the first experiment showed that the increase in salinity and Cu had a significant effect on the percentage, index, and speed of germination, lengths of shoot and root, and dry weights of shoot and root of seedlings so that both treatments and their combination reduced these germination traits. Germination almost stopped under the simultaneous treatment of Cu and salinity at high concentrations. According to the results of the second experiment, salt and Cu at high concentrations caused a decrease in the growth and development of the plant, and this decrease was greater under their combined stressful conditions. Salinity significantly increased the amounts of sodium in the root and shoot but did not affect the amounts of Cu in the root and shoot. In the copper treated conditions, the amount of this metal was increased in the root and shoot of plants.

Conclusions: Although B. scoparia shows high resistance to salinity and tolerates moderate concentrations of Cu, it is unable to tolerate the simultaneous treatment of Cu and salinity. It is also sensitive to high concentrations of Cu. Moreover, considering that the accumulation coefficients (AF, BCF, and TF) for Cu in B. scoparia were less than one, this plant does not seem to be suitable for plant extraction of Cu, although it can be used to stabilize this metal by having suitable biomass and significant absorption of Cu in the root.

References:
1. Al Defferi, M. E., AL-Janabi, Q. A., Mustafa, S. A., AL-Muttarri, A. K., 2019. Phytoremediation of lead and nickel by Bassia scoparia. Plant Arch. 19(2), 3830–3834. http://dx.doi.org/10.13140/RG.2.2.22142.13128.
2. Mousavi Kouhi, S. M., Moudi, M., 2020. Assessment of phytoremediation potential of native plant species naturally growing in a heavy metal-polluted saline–sodic soil. Environ. Sci. Pollut. Res. 27(9), 10027–10038. https://link.springer.com/article/10.1007/s11356-019-07578-6.
3. Usman, A. R. A., Kuzyakov, Y., Stahr, K., 2018. Effect of immobilizing substances and salinity on heavy metals availability to wheat grown on sewage sludge-contaminated soil. Soil Sediment Contam. 14(4), 329–344. https://doi.org/10.1080/15320380590954051.

 

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Calcium carbide (CaC₂) is a good source of acetylene and ethylene, these compounds have an effective role on the physiological processes of plants and the expression of sex in cucumber. To investigate the effect of the method, amount and time of consumption of different levels of calcium carbide on the growth indicators and yield of monoicous cucumber (Cucumis sativus L.), a factorial experiment was conducted in the form of a randomized complete block design in three replications in a farm located in Galugah city of Mazandaran province. The treatments included different amounts of calcium carbide (zero, 5, 10, 15 g m^2-) which were applied in three forms (solid, liquid and gas) and in three growth stages of the plant (4, 6 and 8 leaves). The results showed that the highest number of fruits and fruit yield with 30.4 and 3.08 kg plant^-1 were obtained in the treatment of calcium carbide 15 g m^2- by liquid method and at the time of six leaves, respectively. Also, the highest fresh weight of shoots and roots, plant height, leaf area, leaf nitrogen content and total chlorophyll content were observed in the calcium carbide treatment of 10 g m^2- by gas method and at the time of six leaves. According to the obtained results, applying calcium carbide at the six-leaf stage with concentrations of 10 g m^2- as a gas and 15 g m^2- as a liquid increased the vegetative indicators and the yield of monoicous cucumber, respectively.