Journal of Soil and Plant Interactions

---

In order to investigate phosphorus efficiency (PE) of the barley genotypes in the presence of phosphate-solubilizing microorganisms (PSMs), a greenhouse factorial experiment was conducted as a completely randomized blocks design and 3 replications with 10 Iranian and foreign barley genotypes. The effects of different phosphorus (P) fertilizer treatments including control (P0), phosphate rock (RP), phosphate rock inoculated with phosphate solubilizing fungi (RP+F), phosphate rock inoculated with phosphate solubilizing bacteria (RP+B), phosphate rock inoculated with both fungi and bacteria inoculum (RP+B+F), and soluble phosphate (PS) was studied. After 9 weeks, plants were harvested and shoot dry weight (SDW) and P concentration (PC) was measured and then PE indices were calculated. The results indicated that barley genotypes had significant differences (P<0.01) in the SDW, PC, P content (TP), P acquisition efficiency (PACE) and P utilization efficiency (PUTE). Gara-arpa genotype and line AltICB-98 produced the highest and Rihane-03 genotype produced the lowest shoot dry mass at the P-free treatment (P0). The inoculation with PSMs significantly increased plant growth parameters and PACE as the fungi inoculation was more effective than bacteria and mixed inoculation of fungi and bacteria. With fungi inoculation, the average PC increased from 1.58 to 2.9 mg/g SDW, PACE from 0.12 to 0.27 and PE from 0.40 to 0.69. Among the varieties, Yea-168 was efficient in P acquisition, Sahand was efficient in P utilization, and Gara-arpa and line AltICB-98 were efficient in both acquisition and utilization of P. Thus, it is concluded that selecting P-efficient varieties along with inoculation by phosphate-solubilizing microorganisms could decrease application of chemical fertilizers due to increasing P absorption from phosphate rock and insoluble forms of P in the soil.

---

Zinc (Zn) deficiency is one of the most widespread micronutrients deficiencies in plants that causes severe reduction in their growth and yield. An increase in reactive oxygen species (ROS) levels and a decrease in efficiency of detoxification mechanisms may be the major reasons for impairment of various cellular functions in Zn-deficient plants. This study was conducted in order to investigate the effects of individual and simultaneous inoculation of endophytic fungus, Piriformospora indica, and plant growth-promoting rhizobacterium, Azotobacter chroococcum, on biochemical properties, antioxidant enzyme activities and growth of wheat plant (Niknejad cultivar) in Zn deficiency and sufficiency conditions. The experiment was conducted in greenhouse of the Soilless Culture Center of Isfahan University of Technology by using the sterile sand-perlite (2:1 v/v) medium, as factorial in a completely randomized design with three replications. The results showed that Zn deficiency decreased shoot dry weight, carotenoids' content, total amount of Zn in shoot and antioxidant enzyme activities in control treatment (plants were not inoculated with fungi and bacteria). Inoculation of individual and simultaneous of P. indica and A. chroococcum resulted in increase of shoot dry weight at Zn deficiency condition. However, the highest shoot dry weight belonged to individual inoculation of A. chroococcum. Inoculated plants with P. indica had the highest total amount of Zn in shoot and concentration of carotenoids at both levels of Zn. Whereas, individual inoculation of A. chroococcum and also in combination with P. indica had only significant effect on increasing the total amount of Zn in shoot at Zn deficiency condition. Inoculation of A. chroococcum alone and also in combination with P. indica resulted in inducing antioxidant enzyme activities of ascorbate peroxidase and peroxidase in response to Zn deficiency. Whereas, individual inoculation of P. indica resulted in increasing and decreasing the activities of peroxidase and ascorbate peroxidase, respectively. In general, inoculation of wheat plant (Niknejad cultivar) with the studied microorganisms in this research, particularly inoculation of A. chroococcum, can serve as a useful method for alleviating deleterious effects of Zn deficiency stress.

---

Information about the effect of endophytic fungus Piriformospora indica on wheat response to stress conditions is very limited and sometime contradictory. This greenhouse research was conducted in a hydroponic culture to investigate the inoculation effects of mycorrizhal-like fungus, P. indica, on enzymatic and non–enzymatic defense mechanisms of wheat (Triticum aestivum L., cv. Niknejad) at two levels of phosphorus (P) supply (deficient and sufficient). The experiment was factorial, based on a completely randomized design with three replications. Sixty days after applying the treatments, plants were harvested and shoot dry weight and concentration of P, iron, zinc and activity of antioxidant enzymes like catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX) and chlorophyll a, b and carotenoids contents were measured. Results showed that P-deficiency reduced shoot dry weight and concentration of P and iron and increased concentration of zinc in the shoots. Inoculation of wheat roots with P. indica in P-deficiency condition resulted in significant increasing of shoot dry weight and P concentration. Also, chlorophyll a, b contents and concentration of carotenoids in P-deficiency condition was significantly higher than P-sufficiency condition. Inoculation of P. indica to wheat roots decreased chorophyll a, b contents and concentration of carotenoids. Inoculation of P. indica in P-deficiency condition significantly decreased the activity of GPX and significantly increased the activity of CAT and GPX in P-sufficiency condition. In general, inoculation of fungus P. indica to wheat plant could be recommended as an effective method to alleviate deleterious effects of P-deficiency and increase its tolerance to this stress.

---

In order to determine the critical period for weed control of greenhouse cucumber, an experiment was conducted in 2012 in a soil greenhouse located 25 km from Mashhad, as a randomized complete blocks design with three replications. The experiment consisted of two treatment series of weed interference. The first series consisted of weed-interference periods (including 14, 28, 42, 56, 70 and 84 days after emergence and the entire growth period of greenhouse cucumber) and the second series consisted of weed-free periods (including 14, 28, 42, 56, 70 and 84 days after emergence and the whole period of greenhouse cucumber growth). Results of this study showed that red root pigweed, common purslane, black nightshade, dwarf mallowand and common lambsquarters were the weeds with the highest density and biomass. Increasing or decreasing the weed-interference and weed-free periods led to changes in density, biomass, relative density and relative biomass of these plants. If 10, 5, and 1% of greenhouse cucumber yield loss are acceptable, then weed control must be carried out from 23 to 77 days (54 days), 18 to 94 days (76 days), and 16 to 107 days (91 days) after the greenhouse cucumber emerges, respectively. In general, the results of this experiment demonstrated that weed control in greenhouse cucumber production is necessary to achieve optimal yield.

---

Abstract
Recently, with the rapid growth of industry and agriculture, the contamination of agricultural soils with the cadmium (Cd) and microplastic particles has become a serious issue. Simultaneous presence of microplastics and Cd in soil can cause various biological effects, especially in the early stages of plant growth. In this research, the effect of Cd stress in the presence of polyvinyl chloride (PVC) microplastic particles was investigated in the early stages of the growth of foxtail millet (Setaria italica L., cv. Bastan). The experiment was arranged in a factorial according to the completely randomized design with three replicates based on five concentrations of Cd (0, 50, 100, 150, and 200 µM) and PVC microplastic (0, 1, 2, 4, and 6%). The studied traits included percentage and inhibition of germination, rate and mean germination time, seedling vigor index, weight of mobilized seed reserve, seed reserve utilization efficiency, seed reserve depletion percentage, relative seed germination, seedling toxicity level, germination tolerance index and root tolerance index. The results showed that both pollutants led to the decrease of most germination indices, however, certain concentrations of PVC with Cd stress improved the desired indices. So that germination percentage and seed reserve utilization efficiency in 200 µM Cd concentration with 1% of PVC increased by 43.2 and 206%, respectively, compared to the concentration of 200 µM Cd alone. The highest inhibition of germination percentage belonged to 200 μM Cd concentration, which was reduced by 52.4% with the application of 1% microplastic. Although PVC microplastic particles had adverse effects on the germination process of foxtail millet seeds, but in the presence of Cd in the soil, low concentrations of PVC can have some moderating effects on Cd toxicity.

Background and Objective: Simultaneous contamination of soil with microplastics and heavy metals may pose a more severe threat to the soil and plants than the contamination of one of them alone (Wang et al., 2021). Due to their high adsorption capacity and carrier effect, microplastics can change the accessibility and toxicity of co-existing environmental pollutants in soil organisms and plants. Therefore, our objective was to investigate the possible effect of PVC and Cd on Cd toxicity, germination, and growth characteristics of seedlings. 

Methods: The factorial completely randomized design experiment with three replicates was conducted. The seeds disinfected with 5% hypochlorite were placed in a sterile petri dish with 20 ml of 0, 50, 100, 150, 200 µM Cd and 0, 1, 2, 4, and 6% PVC and were kept at 25°C for seven days. The seeds were counted once every 24 hours until the seventh day. Then, the root and shoot lengths were measured in centimeters. Each of the seedling parts was separated from each other, oven-dried at 70°C for 48 hours and weighed. Germination percentage, germination rate, seedling vigor index, mean germination time, weight of mobilized seed reserve, seed reserve utilization efficiency, seed reserve depletion percentage, root tolerance index, relative seed germination, germination tolerance index, seedling toxicity level and germination inhibition percentage were calculated. Data were analyzed through the SAS (v. 9.4) statistical program, and means values were compared by LSD test (p < 0.05).

Results: The effect of Cd and PVC on the examined traits was significant at the 1% probability level, except for the germination percentage, which was significant at the 5% probability level. The effect of Cd and PVC on the relative seed germination was not significant. The presence of PVC with Cd improved the percentage of germination, the mean germination time, and the seedling vigor index. The presence of microplastic decreased the adverse conditions of Cd stress and reduced the toxicity level and germination inhibition percentage. Heavy metals can be adsorbed by microplastic particles, which could reduce Cd adverse effects during germination (Yang et al., 2019). However, co-exposure of microplastic and Cd led to a decrease in germination rate. Duan et al. (2018) stated that the simultaneous presence of Cd and microplastic causes the accumulation of pollutants in plant cells and the intensification of oxidative stress, which leads to higher toxicity. The average germination time reduction in the presence of PVC under Cd stress. Due to the increased concentration of pollutants, disturbances were observed in the weight of mobilized seed reserve, seed reserve utilization efficiency, and seed reserve depletion percentage. Under the heavy metals stress, the starch mobility was reduced, and following the reduction of the mobility of seed reserves, the weight of the transferred seed reserves decreased (Seneviratne et al., 2019). Microplastics prevent water and nutrient absorption by the seeds, then delay germination and root growth (Bosker et al., 2019). The presence of microplastics moderated the adverse conditions of Cd stress and reduced the toxicity level, and germination inhibition percentage.

Conclusions: The PVC application moderated the Cd stress and improved the germination tolerance index as a crucial parameter of plant tolerance to stress. Therefore, despite the pollution of microplastic particles in the seed culture environment, our results demonstrated the reducing and balancing effects of PVC on Cd toxicity in foxtail millet seedlings, especially at low concentrations. However, this result needs more research, especially on other plants and in different concentrations of microplastics and Cd in different soils and it should not be considered as a positive effect of microplastics presence in the environment.

References:
1. Bosker, T., Bouwman, L.J., Brun, N.R., Behrens, P., Vijver, M.G., 2019. Microplastics accumulate on pores in seed capsule and delay germination and root growth of the terrestrial vascular plant Lepidium sativum. Chemosphere 226, 774–781. https://doi.org/10.1016/j.chemosphere.2019.03.163
2. Duan, C., Fang, L., Yang, C., Chen, W., Cui, Y., Li, S., 2018. Reveal the response of enzyme activities to heavy metals through in situ zymography. Ecotoxicol. Environ. Saf. 156, 106–115. https://doi.org/10.1016/j.ecoenv.2018.03.015
3. Seneviratne, M., Rajakaruna, N., Rizwan, M., Madawala, H.M.S.P., Ok, Y.S., Vithanage, M., 2019. Heavy metal-induced oxidative stress on seed germination and seedling development: a critical review. Environ. Geochem. Health 41(4), 1813–1831. https://doi.org/10.1007/s10653-017-0005-8
4. Wang, F., Wang, X., Song, N., 2021. Polyethylene microplastics increase cadmium uptake in lettuce (Lactuca sativa L.) by altering the soil microenvironment. Sci. Total Environ. 784, 147133. https://doi.org/10.1016/j.scitotenv.2021.147133
5. Yang, J., Cang, L., Sun, Q., Dong, G., Ata-Ul-Karim, S.T., Zhou, D., 2019. Effects of soil environmental factors and UV aging on Cu²⁺ adsorption on microplastics. Environ. Sci. Pollut. Res. 26(22), 23027–23036. https://doi.org/10.1007/s11356-019-05643-8

---

Abstract
Ciprofloxacin, one of the fluoroquinolone antibiotics, accumulates as a pollutant in the soil environment and is uptake by plants due to the widespread use in human and veterinary medicine and its long half-life.
Therefore, this study investigated the effect of a type of organic material called leonardite on ciprofloxacin adsorption. This was considered as a method to reduce the mobility of this pollutant in the soil environment and its uptake by plants. For this purpose, an experiment was carried out with a concentration of ciprofloxacin (0.8 mmol L^-1) at different levels of leonardite (0, 2 and 5%) in a calcareous soil. Leek (Allium Iranicum) was then grown in a factorial experiment based on a completely randomized design with the treatment of leonardite (0, 2 and, 5 %) and ciprofloxacin (0 and 2 mmol L^-1) in three replications. The plants were harvested 42 days after planting and the concentration of CIP in the plants were determined using high performance liquid chromatography (HPLC). The results showed that application of leonardite increased the ciprofloxacin adsorption in the soil. So that the adsorption amount (q_e) of ciprofloxacin reached from 5102 to 5756 mg kg^-1 with the use of 5% leonardite. In addition, the distribution coefficient (K_d) of ciprofloxacin in the presence of 5% leonardite increased 5 times compared to the control, which indicates the immobilization of ciprofloxacin due to its strong adsorption by leonardite. The uptake of ciprofloxacin by leek plants was significantly reduced through the use of leonardite, and it decreased from 4.5 µg g^-1 to 3.2 and 1.7 µg g^-1, respectively, in the presence of 2% and 5% leonardite compared to the control. In general, it seems that leonardite usage can be effective to stabilize ciprofloxacin in polluted soil and to reduce its entry into crops, especially vegetables.

Keywords: Adsorbent, Distribution coefficient, Pollutant, Soil
Background and Objective: Antibiotics are used in treating a wide spectrum of diseases, and are widely employed to promote animal growth (Cycon et al., 2019). As many of those pharmaceuticals are only partially absorbed by the digestive system, a considerable fraction is excreted in its original active form or only partially metabolized. Therefore, the use of animal excrement in agriculture represents one of the principal routes of insertion of antibiotics into the environment. Within that context, plants, principally those of agricultural interest, will be exposed to those compounds when present in the soil (Rocha et al., 2021).
Methods: An agricultural soil (0–20 cm deep) was collected from a farm in Urmia University, and air-dried. After removal of large pieces of plant materials by screening through a 2 mm sieve, the soil was mixed well and stored at 4 °C until use. Pot test had two treatments with leonardite (0, 2 and 5%), and ciprofloxacin (0 and 2 mmol L^-1) in three replicates. Into each pot seeds of leek (Allium Iranicum) were sown at a depth of 0.5 cm. During the test period, the treated pots were placed at a temperature of 25 °C and the soil water moisture was maintained everyday by adding appropriate amount of water. The plants were harvested at the 42th day and ciprofloxacin concentration was measured using HPLC (Liu et al., 2009).
Results: The results showed that the application of leonardite increased adsorption of ciprofloxacin in the calcareous soil, and decreased concentration of ciprofloxacin in leek plants. Therefore, leonardite application is a good choice for controlling ciprofloxacin in the soil environment and preventing its entry into crops, especially vegetables.
Conclusions: The solution to reduce pollution caused by ciprofloxacin is to use efficient and low-cost adsorbents such as leonardite. It will be necessary, however, to consider the co-occurrence of antibiotics in existing environmental matrices (instead of focusing on only a single contaminant).
References:
1. Cycon, M., Mrozik, A., Piotrowska-Seget, Z., 2019. Antibiotics in the Soil Environment-Degradation and Their Impact on Microbial Activity and Diversity. Front. Microbial. 338, 1-45.
2. Rocha, D.C., Rocha, C.S., Tavares, D.S., Calado, S.L.M., Gomes, M.P., 2021. Veterinary antibiotics and plant physiology: An overview. Sci. Total Environ. 767, 144902.
3. Liu, F., Ying, G., Tao, R., Zhao, J., Yang, J., Zhao, L., 2009. Effects of Six Selected Antibiotics on Plant Growth and Soil Microbial and Enzymatic Activities. Environ. Pollut. 157(5), 1636-42.