Chromium (Cr) is classified as a toxic metal as it exerts harmful effects on plants and human life. Bacterial-assisted nano-phytoremediation is an emerging and environment friendly technique that can be used for the detoxification of such pollutants. In current study, pot experiment was conducted in which spinach plants were grown in soil containing chromium (0, 5, 10, 20 mgkg⁻¹) and treated with selected strain of Bacillus sp. and Cu–O nanoparticle (CuONPs). Data related to plant's growth, physiological parameters, and biochemical tests was collected and analyzed using an appropriate statistical test. It was observed that under chromium stress, all plant's growth parameters were significantly enhanced in response to co-application of CuONPs and Bacillus sp. Similarly, higher levels of catalase, superoxide dismutase, malondialdehyde, and hydrogen peroxide were also observed. However, contents of anthocyanin, carotenoid, total chlorophyll, chlorophyll a & b, were lowered under chromium stress, which were raised in response to the combined application of CuONPs and Bacillus sp. Moreover, this co-application has significant positive effect on total soluble protein, free amino acid, and total phenolics. From this study, it was evident that combined application of Bacillus sp. and CuONP alleviated metal-induced toxicity in spinach plants. The findings from current study may provide new insights for agronomic research for the utilization of bacterial-assisted nano-phytoremediation of contaminated sites

Quail bush [Atriplex lentiformis (Torr.) S. Wats] plants were used in removing 2, 4-dinitrophenol (DNP) from wastewater in a hydroponic experiment. The hydroponic system contained three doses of DNP, i.e., 0, 10, and 20 mg L⁻¹. Quail bush plants were sprayed with 0.1 mM salicylic acid (SA) to study its role in resisting DNP toxicity. DNP significantly (p < 0.05) reduced plant growth. Exposure of A. lentiformis plants to 20 mg L⁻¹ of DNP reduced the total chlorophyl and relative water content by 39 and 24%, respectively. SA improved the antioxidant defense in terms of ascorbate peroxidase (APX) and polyphenol oxidase (PPO) activities. SA alleviated DNP toxicity by enhancing the production of osmoprotectants, e.g.,proline, phenols, and carbohydrates. SA enhanced the removal efficiency of DNP and the highest removal efficiency (96%) was recorded in the plants sprayed with SA and grown on 10 mg L⁻¹ of DNP. A. lentiformis is a halophytic plant that has good physiological characteristics to resist 2, 4-dinitrophenol toxicity in wastewaters and is qualified to purify water from these harmful compounds. Exogenous application of 0.1 mM SA increased the defense system in A. lentiformis against 2, 4-dinitrophenol toxicity and enhanced the removal efficiency.

Nanoparticles (NPs) are released and dispersed in the environment because of increased manufacturing and use of nano products. NPs disturb the growth of plants depending upon types, exposure duration and plant species. The purpose of this research was to explore the role of gibberellic acid (GA) exposure through foliar route on wheat growth under alone or combined soil application of cerium oxide (CeO₂), zinc oxide (ZnO), and titanium dioxide (TiO₂) NPs. GA was foliar-applied (200 mg/L) on the wheat plants treated with individual and in all possible combination of the selected NPs. Explorations have revealed that the combination of NPs and GA worked well to enhance the plant growth and selected nutrient status than NPs alone. Furthermore, GA decreased the boosted antioxidant enzyme activities under the combination and individual NPs compared to the alone NPs treated plants, lowered the oxidative stress in wheat plants which provided the additional proof that GA decreased oxidative damage in plants. Combined NPs showed differential effects than individual NPs application irrespective of GA exposure which varied with NPs combination and studied parameters of plants. GA + NPs differentially affected the potassium, phosphorus, iron and manganese concentrations in wheat tissues than NPs alone treatments. Overall, GA can be applied when there is excess of NPs (either alone or in combination) in the growth medium to ensure the growth of crops. However, further studied are needed with other plant species and alone or combined use of different NPs under GA treatment before any final recommendation.

Soil salinization has become a major issue around the world in recent years, as it is one of the consequences of climate change as sea levels rise. It is crucial to lessen the severe consequences of soil salinization on plants. A pot experiment was conducted to regulate the physiological and biochemical mechanisms in order to evaluate the ameliorative effects of potassium nitrate (KNO₃) on Raphanus sativus L. genotypes under salt stress. The results from the present study illustrated that the salinity stress induced a significant decrease in shoot length, root length, shoot fresh weight, shoot dry weight, root fresh weight, root dry weight, number of leaves per plant, leaf area chlorophyll-a, chlorophyll-b, total chlorophyll, carotenoid, net photosynthesis, stomatal conductance, and transpiration rate by 43, 67, 41, 21, 34, 28, 74, 91, 50, 41, 24, 34, 14, 26, and 67%, respectively, in a 40 day radish while decreased by 34, 61, 49, 19, 31, 27, 70, 81, 41, 16, 31, 11, 21, and 62%, respectively, in Mino radish. Furthermore, MDA, H₂O₂ initiation, and EL (%) of two varieties (40 day radish and Mino radish) of R. sativus increased significantly (P < 0.05) by 86, 26, and 72%, respectively, in the roots and also increased by 76, 106, and 38% in the leaves in a 40 day radish, compared to the untreated plants. The results also elucidated that the contents of phenolic, flavonoids, ascorbic acid, and anthocyanin in the two varieties (40 day radish and Mino radish) of R. sativus increased with the exogenous application of KNO₃ by 41, 43, 24, and 37%, respectively, in the 40 day radish grown under the controlled treatments. Results indicated that implementing KNO₃ exogenously in the soil increased the activities of antioxidants like SOD, CAT, POD, and APX by 64, 24, 36, and 84% in the roots and also increased by 21, 12, 23, and 60% in the leaves of 40 day radish while also increased by 42, 13, 18, and 60% in the roots and also increased by 13, 14, 16, and 41% in the leaves in Mino radish, respectively, in comparison to those plants grown without KNO₃. We found that KNO₃ substantially improved plant growth by lowering the levels of oxidative stress biomarkers, thereby further stimulating the antioxidant potential system, which led to an improved nutritional profile of both R. sativus L. genotypes under normal and stressed conditions. The current study would offer a deep theoretical foundation for clarifying the physiological and biochemical mechanisms by which the KNO₃ improves salt tolerance in R. sativus L. genotypes.

Soil contamination with toxic environmental pollutants [such as cadmium (Cd)] is becoming a serious global problem due to rapid development of social economy. To improve the growth and yield of a plant, various chelating agents, such as ethylenediaminetetraacetic acid (EDTA) and citric acid (CA), can be applied to the soil; such application not only increases plant uptake of metals from the soil but also promotes plant absorption of micronutrient fertilizers from the medium. For this purpose, we have conducted a pot experiment using the exogenous application of CA (2.5 mM) and EDTA (2.5 mM) in pepper (Capsicum annuum L.) seedlings grown under the varying levels of Cd (0, 50 and 100 µM) in the soil. M]. Our results depicted that Cd addition to the soil significantly (P < 0.05) decreased plant growth and biomass, gas exchange attributes, and mineral uptake by C. annuum when compared to the plants grown without the addition of Cd. However, Cd toxicity boosted the production of reactive oxygen species (ROS) by increasing the content of malondialdehyde (MDA), which is the indication of oxidative stress in C. annuum, and was also manifested by hydrogen peroxide (H₂O₂) content and electrolyte leakage to the membrane-bound organelles. The results showed that the activities of various antioxidative enzymes, such as superoxidase dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX), and their specific gene expression and also the content of non-enzymatic antioxidants, such as phenolic, flavonoid, ascorbic acid, and anthocyanin, initially increased with an increase in the Cd concentration in the soil. The results also revealed that the levels of soluble sugar, reducing sugar, and non-reducing sugar were decreased in plants grown under elevating Cd levels, but the accumulation of the metal in the roots and shoots of C. annuum, was found to be increased. The negative impacts of Cd injury were reduced by the application of EDTA and CA, which increased plant growth and biomass, improved photosynthetic apparatus, antioxidant enzymes and their gene expression, and mineral uptake, as well as diminished the exudation of organic acids and oxidative stress indicators in C. annuum by decreasing Cd toxicity. Here, we conclude that the application of EDTA and CA under the exposure to Cd stress significantly improved plant growth and biomass, photosynthetic pigments, and gas exchange characteristics; regulated antioxidant defense system and essential nutrient uptake; and balanced organic acid exudation pattern in C. annuum.

Salinity has emerged as a major threat to food security and safety around the globe. The crop production on agricultural lands is squeezing due to aridity, climate change and low quality of irrigation water. The present study investigated the effect of biogenic silicon (Si) sources including wheat straw biochar (BC-ws), cotton stick biochar (BC-cs), rice husk feedstock (RH-fs), and sugarcane bagasse (SB), on the growth of two consecutive maize (Zea mays L.) crops in alkaline calcareous soil. The application of SB increased the photosynthetic rate, transpiration rate, stomatal conductance, and internal CO₂ concentration by 104, 100, 55, and 16% in maize 1 and 140, 136, 76, and 22% in maize 2 respectively. Maximum yield (g/pot) of cob, straw, and root were remained as 39.5, 110.7, and 23.6 while 39.4, 113.2, and 23.6 in maize 1 and 2 respectively with the application of SB. The concentration of phosphorus (P) in roots, shoots, and cobs was increased by 157, 173, and 78% for maize 1 while 96, 224, and 161% for maize 2 respectively over control by applying SB. The plant cationic ratios (Mg:Na, Ca:Na, K:Na) were maximum in the SB applied treatment in maize 1 and 2. The study concluded that the application of SB on the basis of soluble Si, as a biogenic source, remained the best in alleviating the salt stress and enhancing the growth of maize in rotation. The field trials will be more interesting to recommend the farmer scale.

Nano-enabled strategies have emerged as promising alternatives to resolve heavy metals (HMs) related harms in an eco-friendly manner. Here, we explored the potential of biogenic silicon nanoparticles (SiNPs) in alleviating cadmium (Cd) stress in rapeseed (Brassica napus L.) plants by modulating cellular oxidative repair mechanisms. Biogenic SiNPs of spherical shapes with size ranging between 14 nm and 35 nm were synthesized using rice straw extract and characterized through advanced characterization techniques. A greenhouse experiment results showed that SiNPs treatment at 250 mg kg⁻¹ significantly improved growth parameters, including fresh weight (33.3 %) and dry weight (32.6 %) of rapeseed plants than Cd-treated control group. Photosynthesis and leaf gas exchange parameters were also positively influenced by SiNPs treatment, indicating enhanced photosynthetic efficiency. Additionally, SiNPs treatment at 250 mg kg⁻¹ increased the activities of antioxidant enzymes such as superoxide dismutase (19.1 %), peroxidase (33.4 %), catalase (14.4 %), and ascorbate peroxidase (33.8 %), which may play a crucial role in ROS scavenging and reduction in Cd-induced oxidative stress. TEM analysis revealed that SiNPs treatment effectively mitigated Cd-induced damage to leaf ultrastructure, while qPCR analysis showed that SiNPs treatment changed the expressions of the antioxidant defense and stress related genes. Moreover, SiNPs treatment significantly influenced the Cd accumulation and Si contents in plants. Overall, our findings revealed that biogenic SiNPs have great potential to serve as a sustainable, eco-friendly, and non-toxic alternative for the remediation of Cd toxicity in rapeseed plants.

Currently, nanotechnology is widely used in agriculture and horticulture. Nanofertilizers are essential for encouraging vegetative growth and flowering, as well as enhancing productivity and fruit quality. These nanoparticles are viewed as growth promoters as well. The current study was therefore carried out during the two successive seasons of 2021 and 2022 on 14-year-old trees grown in clay soil in a field experiment at the Pomology Department Research orchard, Faculty of Agriculture, Assiut University, Egypt. The effects of conventional vs. nano-micronutrients as foliar fertilizers on the fruit yield, quality, and mineral nutrition status of pomegranate trees were studied. The foliar application of all treatments on pomegranate trees remarkably increased yield and physical properties of fruits as well as improved the levels of total soluble solids percentage, anthocyanin pigment, flavonol, total phenols, antioxidant activity and nutrients status compared with the controls during the 2021 and 2022 seasons. The lowest fruit cracking percentages were obtained by the spraying of nano-micronutrients (4.33–5.70 %) compared with the other treatments and the control, which gave the highest percentages (10.45–11.43 %). The highest increments in yield, physical properties of fruits and levels of total soluble solids percentage, anthocyanin pigment, flavonol, total phenols, and antioxidant activity were noticed by the spraying of nano-micronutrients especially at 1000 and/or 1500 µg mL⁻¹. It could be concluded that the use of nanofoliar fertilization in pomegranate cultivation may improve the yield, quality, and nutritional status of pomegranate fruits.

Due to increasing global climate change problems to biota, salinity has been recognized as a realistic hazard critically affects the sustain agri-food production and crop quality in many regions of the world. Nanotechnology as an innovative approach can effectively improve plant performance under risky conditions such as salinity. Taking in consideration the ameliorative role of nanoparticles such as calcium nanoparticles (Ca-NPs) in enhancing plant growth and tolerance against various abiotic stresses, the present study was undertaken to illuminate the powerful effect and the underlying mechanism of soil-applied Ca-NPs (20 mM) in preventing salt damage at saline conditions (NaCl at 50, 100 and 200 mM) in tomato. Data revealed that NaCl drastically imposed the morphological parameters, primary and secondary metabolism, photosynthesis pigment content, hydrogen peroxide and lipid peroxidation levels, antioxidant enzyme activities, mineral contents, and protein patterns. In contrast, the supplementation of exogenous Ca-NPs modified salinity toxicity effects by improving the survival, growth parameters, anabolic (soluble ions and osmolytes) and defense mechanisms (enzymatic and nonenzymatic antioxidants). Interestingly, under lethal salinity level (200 mM), Ca-NPs was capable of suppressing the excessive damage effect of salinity by up-regulating the performance of the plants when these plants were completely dead in the absence of Ca-NPs. The descriptive cluster analysis separated treatments and characteristics into 3 to elucidate negative and positive correlations.  Moreover, Ca-NPs was more efficient than CaCl₂ in eliciting salt tolerance under all investigated NaCl levels. Therefore, all these findings together conclude that Ca-NPs have a positive role in motivating resilience strategies in tomato plants toward salt stress via lessening the ROS overproduction, stimulating enzymatic antioxidants, promoting osmolytes accumulation, and renovating protein profile under mild and severe salinity levels.

Zinc oxide nanoparticles (nZn) have emerged as vital agents in combating arsenic (As) stress in plants. However, their role in mitigation of As induced oxidative stress is less studied. Therefore, this study aimed to assess the comparative role of nZn and ZnO in alleviating As toxicity in rice genotype “9311”. The results of this study revealed that nZn demonstrated superior efficacy compared to ZnO in mitigating As toxicity. This superiority can be attributed to the unique size and structure of nZn, which enhances its ability to alleviate As toxicity. Exposure to As at a concentration of 25 μM L^-1 led to significant reductions in shoot length, root length, shoot dry weight, and root dry weight by 39%, 51%, 30%, and 46%, respectively, while the accumulation of essential nutrients such as magnesium (Mg), potassium (K), iron (Fe), manganese (Mn), and zinc (Zn) decreased by 25%–47% compared to the control plants. Additionally, As exposure resulted in stomatal closure and structural damage to vital cellular components such as grana thylakoids (GT), starch granules (SG), and the nucleolus. However, the application of nZn at a concentration of 30 mg L⁻¹ exhibited significant alleviation of As toxicity, resulting in a reduction of As accumulation by 54% in shoots and 62% in roots of rice seedlings. Furthermore, nZn demonstrated the ability to scavenge reactive oxygen species (ROS) like hydrogen peroxide (H₂O₂) and superoxide anion (O₂^.-), while significantly promoted the gas exchange parameters, chlorophyll content (SPAD value), fluorescence efficiency (Fv/m) and antioxidant enzyme activities under As-induced stress. These findings highlight the potential of nZn in mitigating the adverse impacts of As contamination in rice plants. However, further research is necessary to fully comprehend the underlying mechanisms responsible for the protective effects of nZn and to determine the optimal conditions for their application in real-world agricultural settings.