Physiological and growth responses of milk thistle (Silybum marianum (L.) Gaertn.) to soil-applied herbicides.

Milk thistle (Silybum marianum (L.) Gaertn.) is cultivated globally as a valuable medicinal plant. The presence of weeds poses numerous challenges to milk thistle production, making weed management the primary concern in milk thistle fields. Chemical weed management is an economical and promising approach to controlling weeds in cropping systems. Therefore, to investigate the tolerance of milk thistle to soil-applied herbicides, in the spring of 2022, we conducted a pot experiment as a completely randomized factorial design with four replications at the research greenhouse of the University of Birjand, Iran. The applied herbicides included metribuzin, pendimethalin, trifluralin, and ethalfluralin at six doses (0, 50, 75, 100, 125, and 150% of the recommended dose (ai ha-1)). Herbicide treatments had adverse effects on the root and shoot growth of milk thistle. Compared to the control, ethalfluralin at 150% (-60.1%) and metribuzin at 50% (-13.3%) had the highest and lowest herbicide negative effects on root dry weight, respectively. In contrast to the control, we found that ethalfluralin at 150% (-64.4%) and metribuzin at 50% (-9.3%) of the recommended dose had the highest and lowest impacts on shoot dry weight, respectively. Furthermore, herbicide applications decreased the membrane stability index (MSI) and relative water content (RWC). Root and leaf levels of malondialdehyde (MDA), total phenol, DPPH scavenging, soluble carbohydrates, and proline increased after all herbicide treatments, compared to the control. Metribuzin and pendimethalin had fewer negative effects on milk thistle growth. Consequently, these herbicides could be considered as potential options for weed control in milk thistle fields.

Plant extracts as an eco-friendly approach to remove paraquat from aqueous solution.

Nowadays, water pollution by herbicides is known as a global concern. Paraquat (PQ) (1-1-methyl-4,4-bi-pyridinium-dichloride) is a chip with high performance, which is being widely used herbicide to remove weeds from agricultural and natural ecosystems. PQ can contaminate water sources due to its high solubility in water. Human death by poisoning effects of PQ has been reported in several countries. Therefore, the side effects of PQ are a global challenge. This study aimed to investigate the bioremediation of PQ by plant extracts, as a low-cost, nontoxic, and natural absorbent to remove PQ from aqueous solutions in different conditions. In this regard, the extracts of common purslane (portulaca oleracea), florist kalanchoe (kalanchoe blossfeldiana), and jade plant (crassula portulaca) were used as adsorbents. For this purpose, the effect of various parameters such as contact time, initial concentration of PQ solution, temperature, pH, and amount of extract was investigated. The results of present study showed that P. oleracea extract and C. portulaca extracts have higher adsorption efficiency than k. blossfeldiana extract. The highest PQ removal was obtained by P. oleracea extract (79.04%) and C. portulaca extract (78.72%) at pH = 11, the adsorbent content of 0.2 mg L-1, and the lowest absorption of PQ (50.6%) was obtained by K. blossfeldiana extract. The highest PQ removal by plant extract was observed at 30 min for P. oleracea and C. portulaca, and at 15 min for k. blossfeldiana extract. Moreover, surface absorption capacity increased with increasing plant extract concentration, decreasing PQ concentration and decreased with increasing temperature. Finally, it can be concluded that plant extract can help to remove PQ from the aqueous solution.

Contamination of raw water with herbicides such as paraquat (PQ) is recognized as a problem in many countries. PQ is known as a chemical contaminant that is highly toxic with high water solubilities (620 g/l) among herbicides. Despite the ban on the use of PQ in some countries, due to its low price, high efficiency at low concentrations, and high speed of paraquat in suppressing weeds, today this herbicide is used to control a wide range of weeds in the world. In recent years, various approaches to removing PQ from the environment have been studied. Some of these methods are relatively time-consuming and expensive, with large amounts of sludge and hazardous by-products. Among the mentioned methods, the adsorption process shows the simplicity of operation, low-cost process, and high efficiency in removing PQ from water. Recently, many adsorbents have been developed to remove PQ from aqueous solutions, including biochar, activated carbon, chitosan and alginate, clay, rice husk, and bentonite. Plant extracts may be known as new adsorbent materials for removing PQ from water as an eco-friendly and economical process. Therefore, in this study we investigate the plant extracts performance as adsorbents in PQ removal from water.

Removal of paraquat from aqueous solutions by plant extracts as an ecofriendly approach.

Paraquat is a very water-soluble herbicide widely used in agricultural and nonagricultural lands. The removal of paraquat from polluted water is very essential. Hence, three experiments were arranged separately to investigate the ability of plant extracts include Aloe vera, Portulaca grandiflora, kalanchoe daigremontiana, Sedum rubotinctum, Brassica rapa var. rapa, Helxine soleirolii, Brassica oleracea var. capitata, Crassula ovate, Aptenia cordifolia, Tradescantia albiflora to the removal of paraquat (PQ) from water. In the 1st experiment, High-performance liquid chromatography was used to determine the removal rate of PQ by using plant extracts. In the 2nd and 3rd experiments, PQ solutions were subjected to plant extracts treatments and then spray on the leaves of littleseed canarygrass (Phalaris minor) under greenhouse and field conditions, respectively. In general, the results of these experiments revealed that all plant extracts resulted in higher PQ removal from water compared to control. The maximum removal of PQ was observed at pH 11, 25 °C, 30 Min, and 0.2 mL in the presence of plant extracts. In the presence of P. grandiflora, C. ovate, k. daigremontiana, A. cordifolia, H. soleirolii, Aloe vera, S. rubotinctum, B. oleracea var. capitata, B. rapa var. rapa, and T. albiflora plant extracts, PQ removal from water increased to 68.34%, 65.45%, 63.97%, 59.81%, 59.29%, 55.44%, 52.06%, 50.34%, 48.86%, and 46.44% under normal conditions and 79.71%, 78.61%, 78.00%, 75.83%, 74.66%, 72.12%, 71.57%, 71.02%, 69.35%, and 68.73% under optimum conditions, respectively. Results of the 2nd and 3rd experiments were demonstrated a decrease in PQ performance on littleseed canarygrass control. It can be concluded that plant extracts can reduce the residual of PQ in water bodies.

The ability of Silybum marianum to phytoremediate cadmium and/or diesel oil from the soil.

Phytoremediation is a new ecological and cost-effective technology applied for cleaning heavy metals and total petroleum hydrocarbon contaminated (TPH-contaminated) soils. This study was conducted to evaluate the potential of milk thistle (Silybum marianum) to phytoremediate cadmium (Cd (II)) from contaminated soils. To this end, the investigators applied a completely randomized design with the factorial arrangement and four replications. The results indicated that all the evaluated parameters of S. Marianum, including shoot and root fresh and dry weight, as well as shoot and root Cd, were significantly influenced by Cd (II) concentration and diesel oil (DO). The Cd-contaminated soil showed minor declining effects on the produced plant biomass, whereas the DO-contaminated soil had more inhibitory effects. Moreover, the soil contaminated with both Cd and DO led to adverse effects on the plant biomass. The shoot and root Cd concentration had an increasing trend in the presence of DO as the bioconcentration factor (BCF) by 1.740 (+90.78%), 1.410 (+36.89%), 2.050 (+31.41%), 1.68 (+32.28%), and 1.371 (+22.41%) compared to the soil without DO at Cd (II) concentrations of 20, 40, 60, 80, and 100 mg/kg, respectively. Biological accumulation coefficient also showed the same trend as the BCF. In all the treatments, the translocation factor was >1. Therefore, it was demonstrated that milk thistle had high potential for transferring Cd from root to shoot and reducing its concentration in the soil. Moreover, the study revealed that milk thistle had high potential for absorbing Cd in the soil contaminated with Cd and DO.

The effect of olive husk extract compared to the edta on Pb availability and some chemical and biological properties in a Pb-contaminated soil.

It was found that using chelating agents increases the efficiency of heavy metal extraction, however, they may have negative effects on soil ecosystem quality. A pot experiment was conducted in a completely randomized design with three replications in order to evaluate the effect of EDTA and Olive Husk Extract (OHE) on some chemical and biological properties of the Pb-contaminated soil. The experimental treatments included EDTA (2 g Na2EDTA salt per kg soil), OHE (2 g TDS of OHE per kg soil) and control (without the chelating agent). The results revealed that the EDTA and OHE treatments increased the Pb availability by 17.7% and 5.5% in comparison to the control treatment, respectively. Although EDTA was more effective in increasing the Pb availability but decreased the soil biological quality index (SBQI). The EDTA treatment significantly decreased the dehydrogenase (DH) activity and germination index (GI). The OHE application significantly increased the available-P, available-K, total N and organic carbon content by 339.92%, 40.79%, 20.9%, and 29.7% compared with control treatment, respectively. Furthermore, OHE considerably increased SBQI from 18.96 to 53.48. Compared to the control treatment higher values of soil respiration activity, DH activity, and carbon availability index (CAI) were observed in OHE treatment.

Phytoremediation of lead-contaminated soil by Sinapis arvensis and Rapistrum rugosum.

Nowadays, public concern relating to ecological deleterious effects of heavy metals is on the rise. To evaluate the potential of Rapistrum rugosum and Sinapis arvensis in lead- contaminate phytoremediate, a pot culture experiment was conducted. The pots were filled by soil treated with different rates of leadoxide (PbO) including 0 (control), 100, 200, 300, 400, and 500 mg Pb per 1 kg soil. Germinated seeds were sown. Surprisingly, with increasing concentration of Pb, dry weight of R. rugosum and S. arvensis did not decrease significantly. In both of species, the concentration of Pb was higher in roots than shoots. In general, S.arvensis was absorbed more Pb compared to R. rugosum. The results revealed high potential of R. rugosum and S. arvensis in withdrawing Pb from contaminated soil. For both species, a positive linear relation was observed between Pb concentration in soil and roots. However, linear relationship was not observed between Pb concentration in the soil and shoots. Although both species test had low ability in translocation Pb from roots to shoots but they showed high ability in uptake soil Pb by roots. Apparently, these plants are proper species for using in phytoremediation technology.

Weeds ability to phytoremediate cadmium-contaminated soil.

An alternative method to other technologies to clean up the soil, air and water pollution by heavy metals is phytoremediation. Therefore, a pot culture experiment was conducted at the College of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran, in 2014 to determine the potential absorption of cadmium by Portulaca oleracea (Common purslane), Solanum nigrum (Black nightshade), Abutilon theophrasti (Velvetleaf) and Taraxacum officinale (Dandelion). The type of experiment was completely randomized design with factorial arrangement and four replications. The soil in pot was treated with different rates of CdCl2.H2O (0 (control), 10, 20, 40, 60, and 80 mg Cd/kg soil) and the plants were sown. With increasing concentration levels, fresh weight and dry weight of shoots and roots of all plant species were reduced. The reduction severity was ranked according the following order, P. oleracea > A. theophrasti > S. nigrum > T. officinale. Bioconcentration factor (BCF), Translocation factor (TF) and Translocation efficiency (TE%) was ranked according the following order, T. officinale > S. nigrum > A. theophrasti > P. oleracea. The results of this study revealed that T. officinale and S. nigrum are effective species to phytoremediate Cd-contaminated soil.

Photochemical behavior of sethoxydim in the presence of vegetable oils.

The photodecomposition of herbicides may be affected by adding vegetable oils to the spray tank. In this study nine vegetable oils were compared to assess the photodecomposition of sethoxydim under natural light conditions. The experiment was conducted as completely randomized factorial design with three replicates at the College of Agriculture, Ferdowsi University of Mashhad, Iran, in 2013. Each herbicidal solution (with and without vegetable oil) was exposed to sunshine with time intervals of 0, 5, 10, 20, 30, 60, 120, and 240 min. The results revealed that the half-life value was increased by adding castor bean and cottonseed oils to 1.39- and 1.18-fold, respectively, compared to nonvegetable oil. These values for turnip, olive, corn, soybean, sunflower, canola, and sesame oils were decreased down to 4.74-, 2.38-, 1.81-, 1.75-, 1.52-, 1.28-, and 1.11-fold, respectively. A positive relationship existed between the half-life of sethoxydim in the presence of vegetable oils and their viscosity. However, a negative relationship was monitored between unsaturated/saturated fatty acids ratio and the monounsaturated value with half-life. A positive relationship also existed between saturated fatty acids, polyunsaturated fatty acids, palmitic acid, and linoleic acid with half-life. This study revealed that the amount of fatty acids in vegetable oils is a determining factor in preventing or facilitating the photodecomposition of sethoxydim.