Synergetic Effects of Zinc, Boron, Silicon, and Zeolite Nanoparticles on Confer Tolerance in Potato Plants Subjected to Salinity

Enriched biochars with silicon and calcium nanoparticles mitigated salt toxicity and improved safflower plant performance

Modifying biochar with nano-nutrients is one of the most effective methods in improving the efficiency of biochar in reducing the adverse effects of environmental stresses such as salinity on plant growth and productivity. The possible effects of solid biochar, nano-silicon dioxide enriched biochar, nano-calcium carbonate enriched biochar, and combined application of these enriched biochars on physiological performance of safflower (Carthamus tinctorius L.) were evaluated under different levels of salt stress (non-saline, 6 and 12 dSm-1). Salt stress increased sodium content, reactive oxygen species generation, and antioxidant enzymes activity, but decreased potassium, calcium, magnesium, iron, zinc, silicon, photosynthetic pigments, leaf water content, and seed yield (by about 36%) of safflower plants. The addition of biochar forms to the saline soil improved growth (up to 24.6%) and seed yield (up to 37%) of safflower by reducing sodium accumulation (by about 32%) and ROS generation and enhancing nutrient uptake, photosynthetic pigments, and water contents of leaves. The combined forms of enriched biochars were the best treatment on reducing salt stress effects on safflower plants. Therefore, application of enriched biochars has a high potential to reduce the harmful effects of salt stress on plants.

Silicon: A valuable soil element for improving plant growth and CO2 sequestration

BACKGROUND

Silicon (Si), the second most abundant and quasi-essential soil element, is locked as a recalcitrant silicate mineral in the Earth's crust. The physical abundance of silicates can play an essential role in increasing plant productivity. Plants store Si as biogenic silica (phytoliths), which is mobilized through a chemical weathering process in the soil.

AIM OF REVIEW

Although Si is a critical element for plant growth, there is still a considerable need to understand its dissolution, uptake, and translocation in agroecosystems. Here, we show recent progress in understanding the interactome of Si, CO2, the microbiome, and soil chemistry, which can sustainably govern silicate dissolution and cycling in agriculture.

KEY SCIENTIFIC CONCEPTS OF THIS REVIEW

Si cycling is directly related to carbon cycling, and the resulting climate stability can be enhanced by negative feedback between atmospheric CO2 and the silicate uptake process. Improved Si mobilization in the rhizosphere by the presence of reactive elements (for example, Ca, Na, Al, Zn, and Fe) and Si uptake through genetic transporters in plants are crucial to achieving the dual objectives of (i) enhancing crop productivity and (ii) abiotic stress tolerance. Furthermore, the microbiome is a symbiotic partner of plants. Bacterial and fungal microbiomes can solubilize silicate minerals through intriguingly complex bioweathering mechanisms by producing beneficial metabolites and enzymes. However, the interaction of Si with CO2 and the microbiome's function in mobilization have been understudied. This review shows that enhancing our understanding of Si, CO2, the microbiome, and soil chemistry can help in sustainable crop production during climatic stress events.

Zinc oxide nanoparticles influence on plant tolerance to salinity stress: insights into physiological, biochemical, and molecular responses

A slight variation in ecological milieu of plants, like drought, heavy metal toxicity, abrupt changes in temperature, flood, and salt stress disturbs the usual homeostasis or metabolism in plants. Among these stresses, salinity stress is particularly detrimental to the plants, leading to toxic effects and reduce crop productivity. In a saline environment, the accumulation of sodium and chloride ions up to toxic levels significantly correlates with intracellular osmotic pressure, and can result in morphological, physiological, and molecular alterations in plants. Increased soil salinity triggers salt stress signals that activate various cellular-subcellular mechanisms in plants to enable their survival in saline conditions. Plants can adapt saline conditions by maintaining ion homeostasis, activating osmotic stress pathways, modulating phytohormone signaling, regulating cytoskeleton dynamics, and maintaining cell wall integrity. To address ionic toxicity, researchers from diverse disciplines have explored novel approaches to support plant growth and enhance their resilience. One such approach is the application of nanoparticles as a foliar spray or seed priming agents positively improve the crop quality and yield by activating germination enzymes, maintaining reactive oxygen species homeostasis, promoting synthesis of compatible solutes, stimulating antioxidant defense mechanisms, and facilitating the formation of aquaporins in seeds and root cells for efficient water absorption under various abiotic stresses. Thus, the assessment mainly targets to provide an outline of the impact of salinity stress on plant metabolism and the resistance strategies employed by plants. Additionally, the review also summarized recent research efforts exploring the innovative applications of zinc oxide nanoparticles for reducing salt stress at biochemical, physiological, and molecular levels.

Plant growth regulators mitigate oxidative damage to rice seedling roots by NaCl stress

The aim of this experiment was to investigate the effects of exogenous sprays of 5-aminolevulinic acid (5-ALA) and 2-Diethylaminoethyl hexanoate (DTA-6) on the growth and salt tolerance of rice (Oryza sativa L.) seedlings. This study was conducted in a solar greenhouse at Guangdong Ocean University, where 'Huanghuazhan' was selected as the test material, and 40 mg/L 5-ALA and 30 mg/L DTA-6 were applied as foliar sprays at the three-leaf-one-heart stage of rice, followed by treatment with 0.3% NaCl (W/W) 24 h later. A total of six treatments were set up as follows: (1) CK: control, (2) A: 40 mg⋅ L-1 5-ALA, (3) D: 30 mg⋅ L-1 DTA-6, (4) S: 0.3% NaCl, (5) AS: 40 mg⋅ L-1 5-ALA + 0.3% NaCl, and (6) DS: 30 mg⋅ L-1 DTA-6+0.3% NaCl. Samples were taken at 1, 4, 7, 10, and 13 d after NaCl treatment to determine the morphology and physiological and biochemical indices of rice roots. The results showed that NaCl stress significantly inhibited rice growth; disrupted the antioxidant system; increased the rates of malondialdehyde, hydrogen peroxide, and superoxide anion production; and affected the content of related hormones. Malondialdehyde content, hydrogen peroxide content, and superoxide anion production rate significantly increased from 12.57% to 21.82%, 18.12% to 63.10%, and 7.17% to 56.20%, respectively, in the S treatment group compared to the CK group. Under salt stress, foliar sprays of both 5-ALA and DTA-6 increased antioxidant enzyme activities and osmoregulatory substance content; expanded non-enzymatic antioxidant AsA and GSH content; reduced reactive oxygen species (ROS) accumulation; lowered malondialdehyde content; increased endogenous hormones GA3, JA, IAA, SA, and ZR content; and lowered ABA content in the rice root system. The MDA, H2O2, and O2- contents were reduced from 35.64% to 56.92%, 22.30% to 53.47%, and 7.06% to 20.01%, respectively, in the AS treatment group compared with the S treatment group. In the DS treatment group, the MDA, H2O2, and O2- contents were reduced from 24.60% to 51.09%, 12.14% to 59.05%, and 12.70% to 45.20%. In summary, NaCl stress exerted an inhibitory effect on the rice root system, both foliar sprays of 5-ALA and DTA-6 alleviated damage from NaCl stress on the rice root system, and the effect of 5-ALA was better than that of DTA-6.

Silicon nanoparticles improved the osmolyte production, antioxidant defense system, and phytohormone regulation in Elymus sibiricus (L.) under drought and salt stress

Drought and salt stress negatively influence the growth and development of various plant species. Thus, it is crucial to overcome these stresses for sustainable agricultural production and the global food chain. Therefore, the present study investigated the potential effects of exogenous silicon nanoparticles (SiNPs) on the physiological and biochemical parameters, and endogenous phytohormone contents of Elymus sibiricus under drought and salt stress. Drought stress was given as 45% water holding capacity, and salt stress was given as 120 mM NaCl. The seed priming was done with different SiNP concentrations: SiNP1 (50 mg L-1), SiNP2 (100 mg L-1), SiNP3 (150 mg L-1), SiNP4 (200 mg L-1), and SiNP5 (250 mg L-1). Both stresses imposed harmful impacts on the analyzed parameters of plants. However, SiNP5 increased the chlorophylls and osmolyte accumulation such as total proteins by 96% and 110% under drought and salt stress, respectively. The SiNP5 significantly decreased the oxidative damage and improved the activities of SOD, CAT, POD, and APX by 10%, 54%, 104%, and 211% under drought and 42%, 75%, 72%, and 215% under salt stress, respectively. The SiNPs at all concentrations considerably improved the level of different phytohormones to respond to drought and salt stress and increased the tolerance of Elymus plants. Moreover, SiNPs decreased the Na+ and increased K+ concentrations in Elymus suggesting the reduction in salt ion accumulation under salinity stress. Overall, exogenous application (seed priming/dipping) of SiNPs considerably enhanced the physio-biochemical and metabolic responses, resulting in an increased tolerance to drought and salt stresses. Therefore, this study could be used as a reference to further explore the impacts of SiNPs at molecular and genetic level to mitigate abiotic stresses in forages and related plant species.

Foliar zinc spraying improves assimilative capacity of sugar beet leaves by promoting magnesium and calcium uptake and enhancing photochemical performance

Sugar beet, a zinc-loving crop, is increasingly limited by zinc deficiency worldwide. Foliar zinc application is an effective and convenient way to supplement zinc fertilizer. However, the regulatory mechanism of foliar zinc spraying on sugar beet leaf photosynthetic characteristics remains unclear. Therefore, we investigated the effects of foliar ZnSO4·7H2O application (0, 0.1%, 0.2%, and 0.4%) on the photosynthetic performance of sugar beet leaves under controlled hydroponic conditions. The results indicated that a foliar spray of 0.2% Zn fertilizer was optimal for promoting sugar beet leaf growth. This concentration significantly reduced the leaf shape index of sugar beet, notably increasing leaf area, leaf mass ratio, and specific leaf weight. Foliar spraying of Zn (0.2%) substantially elevated the Zn content in sugar beet leaves, along with calcium (Ca) and magnesium (Mg) contents. Consequently, this led to an increase in the potential photochemical activity of PSII (Fv/Fo) (by 6.74%), net photosynthetic rate (Pn) (11.39%), apparent electron transport rate (ETR) (11.43%), actual photochemical efficiency of PSⅡ (Y (Ⅱ)) (11.46%), photochemical quenching coefficient (qP) (15.49%), and total chlorophyll content (25.17%). Ultimately, this increased sugar beet leaf dry matter weight (11.30%). In the cultivation and management of sugar beet, the application of 0.2% Zn fertilizer (2.88 mg plant-1) exhibited the potential to enhance Zn and Mg contents in sugar beet, improve photochemical properties, stimulate leaf growth, and boost light assimilation capacity. Our result suggested the foliar application of Zn might be a useful strategy for sugar beet crop management.

Tolerance and adaptation mechanism of Solanaceous crops under salinity stress

Solanaceous crops act as a source of food, nutrition and medicine for humans. Soil salinity is a damaging environmental stress, causing significant reductions in cultivated land area, crop productivity and quality, especially under climate change. Solanaceous crops are extremely vulnerable to salinity stress due to high water requirements during the reproductive stage and the succulent nature of fruits and tubers. Salinity stress impedes morphological and anatomical development, which ultimately affect the production and productivity of the economic part of these crops. The morpho-physiological parameters such as root-to-shoot ratio, leaf area, biomass production, photosynthesis, hormonal balance, leaf water content are disturbed under salinity stress in Solanaceous crops. Moreover, the synthesis and signalling of reactive oxygen species, reactive nitrogen species, accumulation of compatible solutes, and osmoprotectant are significant under salinity stress which might be responsible for providing tolerance in these crops. The regulation at the molecular level is mediated by different genes, transcription factors, and proteins, which are vital in the tolerance mechanism. The present review aims to redraw the attention of the researchers to explore the mechanistic understanding and potential mitigation strategies against salinity stress in Solanaceous crops, which is an often-neglected commodity.

Plant Nutrition-New Methods Based on the Lessons of History: A Review

As with new technologies, plant nutrition has taken a big step forward in the last two decades. The main objective of this review is to briefly summarise the main pathways in modern plant nutrition and attract potential researchers and publishers to this area. First, this review highlights the importance of long-term field experiments, which provide us with valuable information about the effects of different applied strategies. The second part is dedicated to the new analytical technologies (tomography, spectrometry, and chromatography), intensively studied environments (rhizosphere, soil microbial communities, and enzymatic activity), nutrient relationship indexes, and the general importance of proper data evaluation. The third section is dedicated to the strategies of plant nutrition, i.e., (i) plant breeding, (ii) precision farming, (iii) fertiliser placement, (iv) biostimulants, (v) waste materials as a source of nutrients, and (vi) nanotechnologies. Finally, the increasing environmental risks related to plant nutrition, including biotic and abiotic stress, mainly the threat of soil salinity, are mentioned. In the 21st century, fertiliser application trends should be shifted to local application, precise farming, and nanotechnology; amended with ecofriendly organic fertilisers to ensure sustainable agricultural practices; and supported by new, highly effective crop varieties. To optimise agriculture, only the combination of the mentioned modern strategies supported by a proper analysis based on long-term observations seems to be a suitable pathway.

Synergistic effect of biochar-based compounds from vegetable wastes and gibberellic acid on wheat growth under salinity stress

Soil salinization is a prevalent form of land degradation particularly in water-deficient regions threatening agricultural sustainability. Present desalinization methods demand excessive water use. Biochar has been recognized as a potential remedy for saline soils and Gibberellic acids (GA3) are known to mediate various biochemical processes aiding in stress mitigation. This study was undertaken at The Islamia University of Bahawalpur during winter 2022-23 to explore the combined effect of biochar and GA3 on wheat (Triticum aestivum L.) in saline conditions. Employing a fully randomized design wheat seeds in 24 pots were subjected to two salinity levels with three replications across eight treatments: T1 to T8 ranging from controls with different soil electrical conductivities (ECs) to treatments involving combinations of GA3, biochar and varying soil ECs. These treatments included T1 (control with soil EC of 2.43dS/m), T2 (salinity stress with soil EC of 5.11dS/m), T3 (10 ppm GA3 with soil EC of 2.43dS/m), T4 (10 ppm GA3 with soil EC of 5.11dS/m), T5 (0.75% Biochar with soil EC of 2.43dS/m), T6 (0.75% Biochar with soil EC of 5.11dS/m), T7 (10 ppm GA3 combined with 0.75% biochar at soil EC of 2.43dS/m) and T8 (10 ppm GA3 plus 0.75% biochar at soil EC of 5.11dS/m). The results indicated that the combined applications of GA3 and biochar significantly enhanced plant growth in saline conditions viz. germination rate by 73%, shoot length of 15.54 cm, root length of 4.96 cm, plant height of 16.89 cm, shoot fresh weight 43.18 g, shoot dry weight 11.57 g, root fresh weight 24.26 g, root dry weight 9.31 g, plant water content 60.77%, photosynthetic rate 18.58(CO2 m-2 s-1) carotenoid 3.03 g, chlorophyll a 1.01 g, chlorophyll b 0.69 g, total chlorophyll contents by 1.9 g as compared to the control. The findings suggest that the combined application of these agents offers a sustainable and effective strategy for cultivating wheat in saline soils. The synergy between biochar and GA3 presents a promising avenue for sustainable wheat cultivation in saline conditions. This combined approach not only improves plant growth but also offers an innovative, water-efficient solution for enhancing agricultural productivity in saline-affected regions.

Alleviation of salinity stress in zinc oxide nanoparticle-treated Lagenaria siceraria L. by modulation of physiochemical attributes, enzymatic and non-enzymatic antioxidative system

Salt stress is a major abiotic stress that affects the world's agricultural soils and crop yield, the system that ensures food production. In the present study, three different concentrations of zinc oxide nanoparticles (250, 500 and 750ZnONPsmg L-1 ) were applied by soil drenching. The treatments aimed to improve the phytochemical characteristics of Lagenaria siceraria L. (bottle gourd) by lowering the oxidative stress brought on by salinity stress (200ppm NaF). Green synthesised ZnO NPs were prepared, having hexagonal and spherical shapes and sizes 16-35nm. Salt stress reduced fresh and dry biomass of plants and improved production of proline. ZnO NPs improved antioxidant response by enhancing catalase, ascorbate peroxidase, superoxide dismutase and peroxidase activities, and protecting cellular structures by eliminating free radicals and reactive oxygen species. The 500mg L-1 ZnO NPs treatment improved total chlorophyll (31%), total soluble sugars (23%) and maintained the gas exchange parameters under salt stress. This treatment also enhanced the biosynthesis of osmotic regulators (proline) by 19%, Na+ by 22% and Zn2+ by 17%, assisting mitigation of salt stress-mediated toxicity in plants. This study demonstrates that ZnO NP-treated seedlings show improved growth attributes, suggesting that ZnO NPs could be advantageous for L. siceraria cultivation in salt polluted areas and could be utilised in place of conventional Zn fertiliser for better crop yield.

Salinity stress and nanoparticles: Insights into antioxidative enzymatic resistance, signaling, and defense mechanisms

Salinized land is slowly spreading across the world. Reduced crop yields and quality due to salt stress threaten the ability to feed a growing population. We discussed the mechanisms behind nano-enabled antioxidant enzyme-mediated plant tolerance, such as maintaining reactive oxygen species (ROS) homeostasis, enhancing the capacity of plants to retain K+ and eliminate Na+, increasing the production of nitric oxide, involving signaling pathways, and lowering lipoxygenase activities to lessen oxidative damage to membranes. Frequently used techniques were highlighted like protecting cells from oxidative stress and keeping balance in ionic state. Salt tolerance in plants enabled by nanotechnology is also discussed, along with the potential role of physiobiochemical and molecular mechanisms. As a whole, the goal of this review is meant to aid researchers in fields as diverse as plant science and nanoscience in better-comprehending potential with novel solutions to addressing salinity issues for sustainable agriculture.

B2 O3 nanoparticles alleviate salt stress in maize leaf growth zones by enhancing photosynthesis and maintaining mineral and redox status

Salt stress induces significant loss in crop yield worldwide. Although the growth-stimulating effects of micronutrient nanoparticles (NPs) application under salinity have been studied, the molecular and biochemical mechanisms underlying these effects are poorly understood. The large size of maize leaf growth zones provides an ideal model system to sample and investigate the molecular and physiological bases of growth at subzonal resolution. Using kinematic analysis, our study indicated that salinity at 150 mM inhibited maize leaf growth by decreasing cell division and expansion in the meristem and elongation zones. Consistently, salinity downregulated cell cycle gene expression (wee1, mcm4, and cyclin-B2-4). B2 O3 NP (BNP) mitigated the stress-induced growth inhibition by reducing the decrease in cell division and expansion. BNP also enhanced the photosynthesis-related parameters. Simultaneously, chlorophyll, phosphoenolpyruvate carboxylase and ribulose-1,5-bisphosphate carboxylase/oxygenase were stimulated in the mature zone. Concomitant with growth stimulation by BNP, mineral homeostasis, particularly for B and Ca, was monitored. BNP reduced oxidative stress (e.g., lessened H2 O2 generation along the leaf zones and reduced lipid peroxidation in the mature zone) induced by salinity. This resulted from better maintenance of the redox status, that is, increased the glutathione-ascorbate cycle in the meristem and elongation zones, and flavonoids and tocopherol levels in the mature zone. Our study has important implications for assessing the salinity stress impact mitigated by BNP on maize growth, providing a basis to improve the resilience of crop species under salinity stress conditions.

"Exogenous boron alleviates salt stress in cotton by maintaining cell wall structure and ion homeostasis"

Salt stress is considered one of the major abiotic stresses that impair agricultural production, while boron (B) is indispensable for plant cell composition and has also been found to alleviate salt stress. However, the regulatory mechanism of how B improves salt resistance via cell wall modification remains unknown. The present study primarily focused on investigating the mechanisms of B-mediated alleviation of salt stress in terms of osmotic substances, cell wall structure and components and ion homeostasis. The results showed that salt stress hindered plant biomass and root growth in cotton. Moreover, salt stress disrupted the morphology of the root cell wall as evidenced by Transmission Electron Microscope (TEM) analysis. The presence of B effectively alleviated these adverse effects, promoting the accumulation of proline, soluble protein, and soluble sugar, while reducing the content of Na+ and Cl- and augmenting the content of K+ and Ca2+ in the roots. Furthermore, X-ray diffraction (XRD) analysis demonstrated a decline in the crystallinity of roots cellulose. Boron supply also reduced the contents of chelated pectin and alkali-soluble pectin. Fourier-transform infrared spectroscopy (FTIR) analysis further affirmed that exogenous B led to a decline in cellulose accumulation. In conclusion, B offered a promising strategy for mitigating the adverse impact of salt stress and enhancing plant growth by countering osmotic and ionic stresses and modifying root cell wall components. This study may provide invaluable insights into the role of B in ameliorating the effects of salt stress on plants, which could have implications for sustainable agriculture.

Application of Silicon, Zinc, and Zeolite Nanoparticles-A Tool to Enhance Drought Stress Tolerance in Coriander Plants for Better Growth Performance and Productivity

Drought stress in arid regions is a serious factor affecting yield quantity and quality of economic crops. Under drought conditions, the application of nano-elements and nano-agents of water retention improved the water use efficiency, growth performance, and yield quantity of drought-stressed plants. For this objective, two field experiments were performed and organized as randomized complete block designs with six replications. The treatments included kaolin (5 t. ha-1) bentonite (12.5 t. ha-1), perlite (1.25 t.ha-1), N-zeolite (1.3 L.ha-1), N-silicon (2.5 L.ha-1), and N-zinc (2.5 L.ha-1). The current study showed that the application of silicon, zinc, and zeolite nanoparticles only positively influenced the morphological, physiological, and biochemical properties of the drought-stressed coriander plant. Exogenous application of N-silicon, N-zinc, and N-zeolite recorded the higher growth parameters of drought-stressed plants; namely, plant fresh weight, plant dry weight, leaf area, and root length than all the other treatments in both seasons. The improvement ratio, on average for both seasons, reached 17.93, 17.93, and 18.85% for plant fresh weight, 73.46, 73.46, and 75.81% for plant dry weight, 3.65, 3.65, and 3.87% for leaf area, and 17.46, 17.46, and 17.16% for root length of drought-stressed plants treated with N-silicon, N-zinc, and N-zeolite, respectively. For physiological responses, the application of N-zeolite, N-silicon, and N-zinc significantly increased leaf chlorophyll content, photosynthetic rate, water use efficiency, chlorophyll fluorescence, and photosystem II efficiency compared with the control in both seasons, respectively. Similar results were observed in antioxidant compounds, nutrient accumulation, and phytohormones. In contrast, those treatments markedly reduced the value of transpiration rate, nonphotochemical quenching, MDA, ABA, and CAT compared to control plants. Regarding the seed and oil yield, higher seed and oil yields were recorded in drought-stressed plants treated with N-zeolite followed by N-silicon and N-zinc than all the other treatments. Application of N-zeolite, N-silicon and N-zinc could be a promising approach to improve plant growth and productivity as well as to alleviate the adverse impacts of drought stress on coriander plants in arid and semi-arid areas.

Silicon Induces Heat and Salinity Tolerance in Wheat by Increasing Antioxidant Activities, Photosynthetic Activity, Nutrient Homeostasis, and Osmo-Protectant Synthesis

Modern agriculture is facing the challenges of salinity and heat stresses, which pose a serious threat to crop productivity and global food security. Thus, it is necessary to develop the appropriate measures to minimize the impacts of these serious stresses on field crops. Silicon (Si) is the second most abundant element on earth and has been recognized as an important substance to mitigate the adverse effects of abiotic stresses. Thus, the present study determined the role of Si in mitigating adverse impacts of salinity stress (SS) and heat stress (HS) on wheat crop. This study examined response of different wheat genotypes, namely Akbar-2019, Subhani-2021, and Faisalabad-2008, under different treatments: control, SS (8 dSm^-1), HS, SS + HS, control + Si, SS + Si, HS+ Si, and SS + HS+ Si. This study's findings reveal that HS and SS caused a significant decrease in the growth and yield of wheat by increasing electrolyte leakage (EL), malondialdehyde (MDA), and hydrogen peroxide (H₂O₂) production; sodium (Na⁺) and chloride (Cl^-) accumulation; and decreasing relative water content (RWC), chlorophyll and carotenoid content, total soluble proteins (TSP), and free amino acids (FAA), as well as nutrient uptake (potassium, K; calcium, Ca; and magnesium, Mg). However, Si application offsets the negative effects of both salinity and HS and improved the growth and yield of wheat by increasing chlorophyll and carotenoid contents, RWC, antioxidant activity, TSP, FAA accumulation, and nutrient uptake (Ca, K, and Mg); decreasing EL, electrolyte leakage, MDA, and H₂O₂; and restricting the uptake of Na⁺ and Cl^-. Thus, the application of Si could be an important approach to improve wheat growth and yield under normal and combined saline and HS conditions by improving plant physiological functioning, antioxidant activities, nutrient homeostasis, and osmolyte accumulation.

Fe-Mn nanocomposites doped graphene quantum dots alleviate salt stress of Triticum aestivum through osmolyte accumulation and antioxidant defense

An investigation was carried out to evaluate the effect of graphene quantum dots (GQD) and its nanocomposites on germination, growth, biochemical, histological, and major ROS detoxifying antioxidant enzyme activities involved in salinity stress tolerance of wheat. Seedlings were grown on nutrient-free sand and treatment solutions were applied through solid matrix priming and by foliar spray. Control seedlings under salinity stress exhibited a reduction in photosynthetic pigment, sugar content, growth, increased electrolyte leakage, and lipid peroxidation, whereas iron-manganese nanocomposites doped GQD (FM_GQD) treated seedlings were well adapted and performed better compared to control. Enzymatic antioxidants like catalase, peroxidase, glutathione reductase and NADPH oxidase were noted to increase by 40.5, 103.2, 130.19, and 141.23% respectively by application of FM_GQD. Histological evidence confirmed a lower extent of lipid peroxidation and safeguarding the plasma membrane integrity through osmolyte accumulation and redox homeostasis. All of these interactive phenomena lead to an increment in wheat seedling growth by 28.06% through FM_GQD application. These findings highlight that micronutrient like iron, manganese doped GQD can be a promising nano-fertilizer for plant growth and this article will serve as a reference as it is the very first report regarding the ameliorative role of GQD in salt stress mitigation.

Nanoengineered particles for sustainable crop production: potentials and challenges

Nanoengineered nanoparticles have a significant impact on the morphological, physiology, biochemical, cytogenetic, and reproductive yields of agricultural crops. Metal and metal oxide nanoparticles like Ag, Au, Cu, Zn, Ti, Mg, Mn, Fe, Mo, etc. and ZnO, TiO2, CuO, SiO2, MgO, MnO, Fe2O3 or Fe3O4, etc. that found entry into agricultural land, alter the morphological, biochemical and physiological system of crop plants. And the impacts on these parameters vary based on the type of crop and nanoparticles, doses of nanoparticles and its exposure situation or duration, etc. These nanoparticles have application in agriculture as nanofertilizers, nanopesticides, nanoremediator, nanobiosensor, nanoformulation, phytostress-mediator, etc. The challenges of engineered metal and metal oxide nanoparticles pertaining to soil pollution, phytotoxicity, and safety issue for food chains (human and animal safety) need to be understood in detail. This review provides a general overview of the applications of nanoparticles, their potentials and challenges in agriculture for sustainable crop production.

Chitosan-Magnesium Oxide Nanoparticles Improve Salinity Tolerance in Rice (Oryza sativa L.)

High-salinity (HS) stress is a global element restricting agricultural productivity. Rice is a significant food crop, but soil salinity has a detrimental impact on its yield and product quality. Nanoparticles (NPs) have been found as a mitigation method against different abiotic stresses, even HS stress. In this study, chitosan-magnesium oxide NPs (CMgO NPs) were used as a new method for rice plants to alleviate salt stress (200 mM NaCl). The results showed that 100 mg/L CMgO NPs greatly ameliorated salt stress by enhancing the root length by 37.47%, dry biomass by 32.86%, plant height by 35.20%, and tetrapyrrole biosynthesis in hydroponically cultured rice seedlings. The application of 100 mg/L CMgO NPs greatly alleviated salt-generated oxidative stress with induced activities of antioxidative enzymes, catalase by 67.21%, peroxidase by 88.01%, and superoxide dismutase by 81.19%, and decreased contents of malondialdehyde by 47.36% and H₂O₂ by 39.07% in rice leaves. The investigation of ion content in rice leaves revealed that rice treated with 100 mg/L CMgO NPs maintained a noticeably higher K⁺ level by 91.41% and a lower Na⁺ level by 64.49% and consequently a higher ratio of K⁺/Na⁺ than the control under HS stress. Moreover, the CMgO NPs supplement greatly enhanced the contents of free amino acids under salt stress in rice leaves. Therefore, our findings propose that CMgO NPs supplementation could mitigate the salt stress in rice seedlings.

Foliar application of silicon, selenium, and zinc nanoparticles can modulate lead and cadmium toxicity in sage (Salvia officinalis L.) plants by optimizing growth and biochemical status

Different techniques have been used to alleviate metal toxicity in medicinal plants; accordingly, nanoparticles (NPs) have a noticeable interest in modulating oxidative stresses. Therefore, this work aimed to compare the impacts of silicon (Si), selenium (Se), and zinc (Zn) NPs on the growth, physiological status, and essential oil (EO) of sage (Salvia officinalis  L.) treated with foliar application of Si, Se, and Zn NPs upon lead (Pb) and cadmium (Cd) stresses. The results showed that Se, Si, and Zn NPs decreased Pb accumulation by 35, 43, and 40%, and Cd concentration by 29, 39, and 36% in sage leaves. Shoot plant weight showed a noticeable reduction upon Cd (41%) and Pb (35%) stress; however, NPs, particularly Si and Zn improved plant weight under metal toxicity. Metal toxicity diminished relative water content (RWC) and chlorophyll, whereas NPs significantly enhanced these variables. The noticeable raises in malondialdehyde (MDA) and electrolyte leakage (EL) were observed in plants exposed to metal toxicity; however, they were alleviated with foliar application of NPs. The EO content and EO yield of sage plants decreased by the heavy metals but increased by the NPs. Accordingly, Se, Si, and Zn NPS elevated EO yield by 36, 37, and 43%, respectively, compared with non-NPs. The primary EO constituents were 1,8-cineole (9.42-13.41%), α-thujone (27.40-38.73%), β-thujone (10.11-12.94%), and camphor (11.31-16.45%). This study suggests that NPs, particularly Si and Zn, boosted plant growth by modulating Pb and Cd toxicity, which could be advantageous for cultivating this plant in areas with heavy metal-polluted soils.

Response of Oxidative Stress and Antioxidant System in Pea Plants Exposed to Drought and Boron Nanoparticles

Pea plants are sensitive to water shortages, making them less attractive to farmers. Hoping to reduce the adverse effects of drought on peas and considering the benefits of boron, this study aimed to investigate the impact of boron nanoparticles on the antioxidant system and oxidative stress biomarkers in drought-stressed peas. Experiments were performed in a greenhouse. Pea plants were treated with a suspension of B₂O₃ nanoparticles at 12.5, 25, and 50 ppm concentrations before ten days of water shortage. Drought effects were induced by maintaining 30% substrate moisture. This study investigated the properties of the nanoparticle suspension and different application methods for spraying and watering pea plants. The effects of B₂O₃ nanoparticles and drought were determined on pea growth indicators, oxidative stress biomarkers, and enzymatic and non-enzymatic antioxidants. Spraying with B₂O₃ nanoparticles at 12.5 ppm most effectively stimulated phenol accumulation; FRAP, DPPH, and ABTS antioxidant capacity; and APX, SOD, GPX, and CAT enzyme activity in pea leaves exposed to drought. In addition, B₂O₃ nanoparticles reduced the amount of MDA and H₂O₂ in pea plants grown on a substrate with insufficient moisture. The most substantial positive effect was found on peas affected by drought after spraying them with 12.5 ppm of B₂O₃ nanoparticles. B₂O₃ nanoparticles positively affected the pea height, leaf area, number of nodules, and yield.

Instigating prevalent abiotic stress resilience in crop by exogenous application of phytohormones and nutrient

In recent times, the demand for food and feed for the ever-increasing population has achieved unparalleled importance, which cannot afford crop yield loss. Now-a-days, the unpleasant situation of abiotic stress triggers crop improvement by affecting the different metabolic pathways of yield and quality advances worldwide. Abiotic stress like drought, salinity, cold, heat, flood, etc. in plants diverts the energy required for growth to prevent the plant from shock and maintain regular homeostasis. Hence, the plant yield is drastically reduced as the energy is utilized for overcoming the stress in plants. The application of phytohormones like the classical auxins, cytokinins, ethylene, and gibberellins, as well as more recent members including brassinosteroids, jasmonic acids, etc., along with both macro and micronutrients, have enhanced significant attention in creating key benefits such as reduction of ionic toxicity, improving oxidative stress, maintaining water-related balance, and gaseous exchange modification during abiotic stress conditions. Majority of phytohormones maintain homeostasis inside the cell by detoxifying the ROS and enhancing the antioxidant enzyme activities which can enhance tolerance in plants. At the molecular level, phytohormones activate stress signaling pathways or genes regulated by abscisic acid (ABA), salicylic acid (SA), Jasmonic acid (JA), and ethylene. The various stresses primarily cause nutrient deficiency and reduce the nutrient uptake of plants. The application of plant nutrients like N, K, Ca, and Mg are also involved in ROS scavenging activities through elevating antioxidants properties and finally decreasing cell membrane leakage and increasing the photosynthetic ability by resynthesizing the chlorophyll pigment. This present review highlighted the alteration of metabolic activities caused by abiotic stress in various crops, the changes of vital functions through the application of exogenous phytohormones and nutrition, as well as their interaction.

Nanoparticles assisted regulation of oxidative stress and antioxidant enzyme system in plants under salt stress: A review

The global biomass production from agricultural farmlands is facing severe constraints from abiotic stresses like soil salinization. Salinity-mediated stress triggered the overproduction of reactive oxygen species (ROS) that may result in oxidative burst in cell organelles and cause cell death in plants. ROS production is regulated by the redox homeostasis that helps in the readjustment of the cellular redox and energy state in plants. All these cellular redox related functions may play a decisive role in adaptation and acclimation to salinity stress in plants. The use of nanotechnology like nanoparticles (NPs) in plant physiology has become the new area of interest as they have potential to trigger the various enzymatic and non-enzymatic antioxidant capabilities of plants under varying salinity levels. Moreover, NPs application under salinity is also being favored due to their unique characteristics compared to traditional phytohormones, amino acids, nutrients, and organic osmolytes. Therefore, this article emphasized the core response of plants to acclimate the challenges of salt stress through auxiliary functions of ROS, antioxidant defense system and redox homeostasis. Furthermore, the role of different types of NPs mediated changes in biochemical, proteomic, and genetic expressions of plants under salt stress have been discussed. This article also discussed the potential limitations of NPs adoption in crop production especially under environmental stresses.

Ethylene Renders Silver Nanoparticles Stress Tolerance in Rice Seedlings by Regulating Endogenous Nitric Oxide Accumulation

Developments in the field of nanotechnology over the past few years have increased the prevalence of silver nanoparticles (AgNPs) in the environment, resulting in increased exposure of plants to AgNPs. Recently, various studies have reported the effect of AgNPs on plant growth at different concentrations. However, identifying the mechanisms and signaling molecules involved in plant responses against AgNPs stress is crucial to find an effective way to deal with the phytotoxic impacts of AgNPs on plant growth and development. Therefore, this study was envisaged to investigate the participation of ethylene in mediating the activation of AgNPs stress tolerance in rice (Oryza sativa L.) through a switch that regulates endogenous nitric oxide (NO) accumulation. Treatment of AgNPs alone hampered the growth of rice seedlings due to severe oxidative stress as a result of decline in sulfur assimilation, glutathione (GSH) biosynthesis and alteration in the redox status of GSH. These results are also accompanied by the higher endogenous NO level. However, addition of ethephon (a donor of ethylene) reversed the AgNP-induced effects. Though the application of silicon nanoparticles (SiNPs) alone promoted the growth of rice seedlings but, interestingly their application in combination with AgNPs enhanced the AgNP-induced toxicity in the seedlings through the same routes as exhibited in the case of AgNPs alone treatment. Interestingly, addition of ethephon reversed the negative effects of SiNPs under AgNPs stress. These results suggest that ethylene might act as a switch to regulate the level of endogenous NO, which in turn could be associated with AgNPs stress tolerance in rice. Furthermore, the results also indicated that addition of l-NG-nitro arginine methyl ester (l-NAME) (an inhibitor of endogenous NO synthesis) also reversed the toxic effects of SiNPs together with AgNPs, further suggesting that the low level of endogenous NO was associated with AgNPs stress tolerance. Overall, the results indicate that the low level of endogenous NO triggers AgNPs stress tolerance, while high level leads to AgNPs toxicity by regulating sulfur assimilation, GSH biosynthesis, redox status of GSH and oxidative stress markers. The results revealed that ethylene might act as a switch for regulating AgNPs stress in rice seedlings by controlling endogenous NO accumulation.

Nanotechnology for sustainable agro-food systems: The need and role of nanoparticles in protecting plants and improving crop productivity

The rapid population growth and environmental challenges in agriculture need innovative and sustainable solutions to meet the growing need for food worldwide. Recent nanotechnological advances found its broad applicability in agriculture's protection and post-harvesting. Engineered nanomaterials play a vital role in plant regulation, seed germination, and genetic manipulation. Their size, surface morphology, properties, and composition were designed for controlled release and enhanced properties in agriculture and the food industry. Nanoparticles can potentially be applied for the targeted and controlled delivery of fertilizers, pesticides, herbicides, plant growth regulators, etc. This help to eliminate the use of chemical-based pesticides and their water solubility, protect agrochemicals from breakdown and degradation, improve soil health, and naturally control crop pathogens, weeds, and insects, ultimately leading to enhanced crop growth and production capacity in the food industry. They can be effectively utilized for nano-encapsulation, seed germination, genetic manipulation, etc., for protecting plants and improving crop productivity, safe and improved food quality, and monitoring climate conditions. Nanoparticles played a crucial role in the uptake and translocation processes, genetically modifying the crops, high seed germination, and productivity. In this article, we have reviewed some important applications of nanoparticles for sustainable agro-food systems. The need and role of nanotechnology concerning challenges and problems faced by agriculture and the food industry are critically discussed, along with the limitations and future prospects of nanoparticles.

Exogenous nano-silicon application improves ion homeostasis, osmolyte accumulation and palliates oxidative stress in Lens culinaris under NaCl stress

Lentil is one of the highly nutritious legumes but is highly susceptible to salinity stress. Silicon has been known to reduce the effect of various environmental stresses including salinity. Moreover, silicon when applied in its nano-form is expected to augment the beneficial attributes of silicon. However, very little is known regarding the prospect of nano-silicon (nSi) application for alleviating the effect of salinity stress in non-silicified plants like lentil. In this study, the primary objective was to evaluate the efficacy of nSi in the alleviation of NaCl stress during germination and early vegetative stages. In this context, different concentrations of nSi (0, 1, 5, 10 g L-1) was applied along with four different concentrations of NaCl (0, 100, 200, 300 mM). The results indicated the uptake of nSi which was confirmed by the better accumulation of silica in the plant tissues. Most importantly, the enhanced accumulation of silica increased the K+/Na+ ratio of the NaCl-stressed seedlings. Moreover, nSi efficiently improved germination, growth, photosynthetic pigments, and osmotic balance. On the other hand, the relatively reduced activities of antioxidative enzymes were surmounted by the higher activity of non-enzymatic antioxidants which mainly scavenged the increased ROS. Reduced ROS accumulation in return ensured better membrane integrity and reduced electrolyte leakage up on nSi application. Therefore, it can be concluded that the application of nSi (more specifically at 10 g L-1) facilitated the uptake of silica and improved the K+/Na+ ratio to reclaim the growth and physiological status of NaCl-stressed seedlings.

Nano-enabled agriculture: How do nanoparticles cross barriers in plants?

Nano-enabled agriculture is a topic of intense research interest. However, our knowledge of how nanoparticles enter plants, plant cells, and organelles is still insufficient. Here, we discuss the barriers that limit the efficient delivery of nanoparticles at the whole-plant and single-cell levels. Some commonly overlooked factors, such as light conditions and surface tension of applied nano-formulations, are discussed. Knowledge gaps regarding plant cell uptake of nanoparticles, such as the effect of electrochemical gradients across organelle membranes on nanoparticle delivery, are analyzed and discussed. The importance of controlling factors such as size, charge, stability, and dispersibility when properly designing nanomaterials for plants is outlined. We mainly focus on understanding how nanoparticles travel across barriers in plants and plant cells and the major factors that limit the efficient delivery of nanoparticles, promoting a better understanding of nanoparticle-plant interactions. We also provide suggestions on the design of nanomaterials for nano-enabled agriculture.

Silicon-Induced Mitigation of NaCl Stress in Barley (Hordeum vulgare L.), Associated with Enhanced Enzymatic and Non-Enzymatic Antioxidant Activities

Salt stress obstructs plant's growth by affecting metabolic processes, ion homeostasis and over-production of reactive oxygen species. In this regard silicon (Si) has been known to augment a plant's antioxidant defense system to combat adverse effects of salinity stress. In order to quantify the Si-mediated salinity tolerance, we studied the role of Si (200 ppm) applied through rooting media on antioxidant battery system of barley genotypes; B-10008 (salt-tolerant) and B-14011 (salt-sensitive) subjected to salt stress (200 mM NaCl). A significant decline in the accumulation of shoot (35-74%) and root (30-85%) biomass was observed under salinity stress, while Si application through rooting media enhancing biomass accumulation of shoots (33-49%) and root (32-37%) under salinity stress. The over-accumulation reactive oxygen species i.e., hydrogen peroxide (H2O2) is an inevitable process resulting into lipid peroxidation, which was evident by enhanced malondialdehyde levels (13-67%) under salinity stress. These events activated a defense system, which was marked by higher levels of total soluble proteins and uplifted activities of antioxidants enzymatic (SOD, POD, CAT, GR and APX) and non-enzymatic (α-tocopherol, total phenolics, AsA, total glutathione, GSH, GSSG and proline) in roots and leaves under salinity stress. The Si application through rooting media further strengthened the salt stressed barley plant's defense system by up-regulating the activities of enzymatic and non-enzymatic antioxidant in order to mitigate excessive H2O2 efficiently. The results revealed that although salt-tolerant genotype (B-10008) was best adopted to tolerate salt stress, comparably the response of salt-sensitive genotype (B-14011) was more prominent (accumulation of antioxidant) after application of Si through rooting media under salinity stress.

Nanoparticle-based toxicity in perishable vegetable crops: Molecular insights, impact on human health and mitigation strategies for sustainable cultivation

With the advancement of nanotechnology, the use of nanoparticles (NPs) and nanomaterials (NMs) in agriculture including perishable vegetable crops cultivation has been increased significantly. NPs/NMs positively affect plant growth and development, seed germination, plant stress management, and postharvest handling of fruits and vegetables. However, these NPs sometimes cause toxicity in plants by oxidative stress and excess reactive oxygen species production that affect cellular biomolecules resulting in imbalanced biological and metabolic processes in plants. Therefore, information about the mechanism underlying interactions of NPs with plants is important for the understanding of various physiological and biochemical responses of plants, evaluating phytotoxicity, and developing mitigation strategies for vegetable crops cultivation. To address this, recent morpho-physiological, biochemical and molecular insights of nanotoxicity in the vegetable crops have been discussed in this review. Further, factors affecting the nanotoxicity in vegetables and mitigation strategies for sustainable cultivation have been reviewed. Moreover, the bioaccumulation and biomagnification of NPs and associated phytotoxicity can cause serious effects on human health which has also been summarized. The review also highlights the use of advanced omics approaches and interdisciplinary tools for understanding the nanotoxicity and their possible use for mitigating phytotoxicity.

Plant Nutrition: An Effective Way to Alleviate Abiotic Stress in Agricultural Crops

By the year 2050, the world’s population is predicted to have grown to around 9–10 billion people. The food demand in many countries continues to increase with population growth. Various abiotic stresses such as temperature, soil salinity and moisture all have an impact on plant growth and development at all levels of plant growth, including the overall plant, tissue cell, and even sub-cellular level. These abiotic stresses directly harm plants by causing protein denaturation and aggregation as well as increased fluidity of membrane lipids. In addition to direct effects, indirect damage also includes protein synthesis inhibition, protein breakdown, and membranous loss in chloroplasts and mitochondria. Abiotic stress during the reproductive stage results in flower drop, pollen sterility, pollen tube deformation, ovule abortion, and reduced yield. Plant nutrition is one of the most effective ways of reducing abiotic stress in agricultural crops. In this paper, we have discussed the effectiveness of different nutrients for alleviating abiotic stress. The roles of primary nutrients (nitrogen, phosphorous and potassium), secondary nutrients (calcium, magnesium and sulphur), micronutrients (zinc, boron, iron and copper), and beneficial nutrients (cobalt, selenium and silicon) in alleviating abiotic stress in crop plants are discussed.

Zinc Oxide Nanoparticles (ZnO NPs), Biosynthesis, Characterization and Evaluation of Their Impact to Improve Shoot Growth and to Reduce Salt Toxicity on Salvia officinalis In Vitro Cultivated

Green synthesis of zinc oxide nanoparticles (ZnO NPs) using plant extracts have recently attracted considerable attention due to their environmental protection benefits and their easy and low cost of fabrication. In the current study, ZnO NPS were synthesized using the aqueous extract of Ochradenus arabicus as a capping and reducing agent. The obtained ZnO NPs were firstly characterized using ultraviolet visible (UV-Vis) spectroscopy, Fourier transform infrared (FTIR), transmission electron microscope (TEM), X-ray diffraction (XRD), energy dispersive X-ray absorption (EDX), zeta potential, and zeta size. All these techniques confirmed the characteristic features of the biogenic synthesized ZnO NPs. Then, ZnO NPs were evaluated for their effects on morphological, biochemical, and physiological parameters of Salvia officinalis cultured in Murashige and Skoog medium containing 0, 75, 100, and 150 mM of NaCl. The results showed that ZnO NPs at a dose of 10 mg/L significantly increased the shoot number, shoot fresh weight, and shoot dry weight of Salvia officinalis subjected or not to the salt stress. For the shoot length, a slight increase of 4.3% was recorded in the plant treated by 150 mM NaCl+10 mg/L ZnO NPs compared to the plant treated only with 150 mM of NaCl. On the other hand, without NaCl, the application of both concentrations 10 mg/L and 30 mg/L of ZnO NPs significantly improved the total chlorophyll content by 30.3% and 21.8%, respectively. Under 150 mM of NaCl, the addition of 10 mg/L of ZnO NPs enhanced the total chlorophyll by 1.5 times, whilst a slight decrease of total chlorophyll was recorded in the plants treated by 150 mM NaCl + 30 mg/L ZnO NPs. Additionally, ZnO NPs significantly enhance the proline accumulation and the antioxidative enzyme activities of catalase (CAT), superoxide dismutase (SOD), and glutathione reductase (GR) in plants under salinity. Our findings revealed that green synthesized ZnO NPs, especially at a dose of 10 mg/L, play a crucial role in growth enhancement and salt stress mitigation. Hence, this biosynthesized ZnO NPs at a concentration of 10 mg/L can be considered as effective nanofertilizers for the plants grown in salty areas.

Foliar Application of Nano-Silicon Improves the Physiological and Biochemical Characteristics of ‘Kalamata’ Olive Subjected to Deficit Irrigation in a Semi-Arid Climate

In Egypt’s arid and semi-arid lands where the main olive production zone is located, evapotranspiration is higher than rainfall during winter. Limited research has used nanomaterials, especially nano-silicon (nSi) to improve the growth, development, and productivity of drought-stressed fruit trees, amid the global water scarcity problem. To assess the role of nSi on drought-sensitive ‘Kalamata’ olive tree growth, and biochemical and physiological changes under drought conditions, a split-plot experiment was conducted in a randomized complete block design. The trees were foliar sprayed with nSi in the field using nine treatments (three replicates each) of 0, 150, and 200 mg·L−1 under different irrigation regimes (100, 90, and 80% irrigation water requirements ‘IWR’) during the 2020 and 2021 seasons. Drought negatively affected the trees, but both concentrations of nSi alleviated drought effects at reduced irrigation levels, compared to the non-stressed trees. Foliar spray of both concentrations of nSi at a moderate level (90% IWR) of drought resulted in improved yield and fruit weight and reduced fruit drop percentage, compared to 80% IWR. In addition, there were reduced levels of osmoprotectants such as proline, soluble sugars, and abscisic acid (ABA) with less membrane damage expressed as reduced levels of malondialdehyde (MDA), H2O2 and electrolyte leakage at 90% compared to 80% IWR. These results suggest that ‘Kalamata’ olive trees were severely stressed at 80% compared to 90% IWR, which was not surprising as it is classified as drought sensitive. Overall, the application of 200 mg·L−1 nSi was beneficial for the improvement of the mechanical resistance, growth, and productivity of moderately-stressed (90% IWR) ‘Kalamata’ olive trees under the Egyptian semi-arid conditions.

Regulation of photosynthesis under salt stress and associated tolerance mechanisms

Photosynthesis is crucial for the survival of all living biota, playing a key role in plant productivity by generating the carbon skeleton that is the primary component of all biomolecules. Salinity stress is a major threat to agricultural productivity and sustainability as it can cause irreversible damage to photosynthetic apparatus at any developmental stage. However, the capacity of plants to become photosynthetically active under adverse saline conditions remains largely untapped. This study addresses this discrepancy by exploring the current knowledge on the impact of salinity on chloroplast operation, metabolism, chloroplast ultrastructure, and leaf anatomy, and highlights the dire consequences for photosynthetic machinery and stomatal conductance. We also discuss enhancing photosynthetic capacity by modifying and redistributing electron transport between photosystems and improving photosystem stability using genetic approaches, beneficial microbial inoculations, and root architecture changes to improve salt stress tolerance under field conditions. Understanding chloroplast operations and molecular engineering of photosynthetic genes under salinity stress will pave the way for developing salt-tolerant germplasm to ensure future sustainability by rehabilitating saline areas.

Zinc Oxide Nanoparticles and Their Biosynthesis: Overview

Zinc (Zn) is plant micronutrient, which is involved in many physiological functions, and an inadequate supply will reduce crop yields. Its deficiency is the widest spread micronutrient deficiency problem; almost all crops and calcareous, sandy soils, as well as peat soils and soils with high phosphorus and silicon content are expected to be deficient. In addition, Zn is essential for growth in animals, human beings, and plants; it is vital to crop nutrition as it is required in various enzymatic reactions, metabolic processes, and oxidation reduction reactions. Finally, there is a lot of attention on the Zn nanoparticles (NPs) due to our understanding of different forms of Zn, as well as its uptake and integration in the plants, which could be the primary step toward the larger use of NPs of Zn in agriculture. Nanotechnology application in agriculture has been increasing over recent years and constitutes a valuable tool in reaching the goal of sustainable food production worldwide. A wide array of nanomaterials has been used to develop strategies of delivery of bioactive compounds aimed at boosting the production and protection of crops. ZnO-NPs, a multifunctional material with distinct properties and their doped counterparts, were widely being studied in different fields of science. However, its application in environmental waste treatment and many other managements, such as remediation, is starting to gain attention due to its low cost and high productivity. Nano-agrochemicals are a combination of nanotechnology with agrochemicals that have resulted in nano-fertilizers, nano-herbicides, nano-fungicides, nano-pesticides, and nano-insecticides being developed. They have anti-bacterial, anti-fungal, anti-inflammatory, antioxidant, and optical capabilities. Green approaches using plants, fungi, bacteria, and algae have been implemented due to the high rate of harmful chemicals and severe situations used in the manufacturing of the NPs. This review summarizes the data on Zn interaction with plants and contributes towards the knowledge of Zn NPs and its impact on plants.

Nanomaterials coupled with microRNAs for alleviating plant stress: a new opening towards sustainable agriculture

Plant growth and development is influenced by their continuous interaction with the environment. Their cellular machinery is geared to make rapid changes for adjusting the morphology and physiology to withstand the stressful changes in their surroundings. The present scenario of climate change has however intensified the occurrence and duration of stress and this is getting reflected in terms of yield loss. A number of breeding and molecular strategies are being adopted to enhance the performance of plants under abiotic stress conditions. In this context, the use of nanomaterials is gaining momentum. Nanotechnology is a versatile field and its application has been demonstrated in almost all the existing fields of science. In the agriculture sector, the use of nanoparticles is still limited, even though it has been found to increase germination and growth, enhance physiological and biochemical activities and impact gene expression. In this review, we have summarized the use and role of nanomaterial and small non-coding RNAs in crop improvement while highlighting the potential of nanomaterial assisted eco-friendly delivery of small non-coding RNAs as an innovative strategy for mitigating the effect of abiotic stress.

Titanium and Zinc Based Nanomaterials in Agriculture: A Promising Approach to Deal with (A)biotic Stresses?

Abiotic stresses, such as those induced by climatic factors or contaminants, and biotic stresses prompted by phytopathogens and pests inflict tremendous losses in agriculture and are major threats to worldwide food security. In addition, climate changes will exacerbate these factors as well as their negative impact on crops. Drought, salinity, heavy metals, pesticides, and drugs are major environmental problems that need deep attention, and effective and sustainable strategies to mitigate their effects on the environment need to be developed. Besides, sustainable solutions for agrocontrol must be developed as alternatives to conventional agrochemicals. In this sense, nanotechnology offers promising solutions to mitigate environmental stress effects on plants, increasing plant tolerance to the stressor, for the remediation of environmental contaminants, and to protect plants against pathogens. In this review, nano-sized TiO₂ (nTiO₂) and ZnO (nZnO) are scrutinized, and their potential to ameliorate drought, salinity, and xenobiotics effects in plants are emphasized, in addition to their antimicrobial potential for plant disease management. Understanding the level of stress alleviation in plants by these nanomaterials (NM) and relating them with the application conditions/methods is imperative to define the most sustainable and effective approaches to be adopted. Although broad-spectrum reviews exist, this article provides focused information on nTiO₂ and nZnO for improving our understanding of the ameliorative potential that these NM show, addressing the gaps in the literature.

The Effective Role of Nano-Silicon Application in Improving the Productivity and Quality of Grafted Tomato Grown under Salinity Stress

This study aims to determine the influence of grafting and nano-silicon fertilizer on the growth and production of tomatoes (Solanumlycopersicum L.) under salinity conditions. A commercial tomato hybrid (cv. Strain B) was used as a scion and two tomato phenotypes were used as rootstocks: S. pimpinellifolium and Edkawy. The rootstock effect was evaluated by growing plants at two NaCl concentrations plus the control (0, 4000, and 8000 ppm NaCl). Nano-silicon foliar application (0.5 ppm) after 20, 28, and 36 days from transplanting was also used to mitigate salinity stress. Antioxidants, hormones, and proline were evaluated for a better understanding of the physiological changes induced by salinity and grafting. The results showed that grafting either on S. pimpinellifolium or Edkawy combined with nano-silicon application enhanced shoot and root growth, fruit yield, and fruit quality. The Edkawy rootstock was more effective than the S. pimpinellifolium rootstock in terms of counteracting the negative effect of salinity. Higher levels of mineral contents, GA3, ABA, and proline were detected in shoots that were subjected to grafting and nano-silicon application compared to the control treatment. This study indicates that grafting and nano-silicon application hold potential as alternative techniques to mitigate salt stress in commercial tomato cultivars.

Salinity responses and tolerance mechanisms in underground vegetable crops: an integrative review

The present review gives an insight into the salinity stress tolerance responses and mechanisms of underground vegetable crops. Phytoprotectants, agronomic practices, biofertilizers, and modern biotechnological approaches are crucial for salinity stress management. Underground vegetables are the source of healthy carbohydrates, resistant starch, antioxidants, vitamins, mineral, and nutrients which benefit human health. Soil salinity is a serious threat to agriculture that severely affects the growth, development, and productivity of underground vegetable crops. Salt stress induces several morphological, anatomical, physiological, and biochemical changes in crop plants which include reduction in plant height, leaf area, and biomass. Also, salinity stress impedes the growth of the underground organs, which ultimately reduces crop yield. Moreover, salt stress is detrimental to photosynthesis, membrane integrity, nutrient balance, and leaf water content. Salt tolerance mechanisms involve a complex interplay of several genes, transcription factors, and proteins that are involved in the salinity tolerance mechanism in underground crops. Besides, a coordinated interaction between several phytoprotectants, phytohormones, antioxidants, and microbes is needed. So far, a comprehensive review of salinity tolerance responses and mechanisms in underground vegetables is not available. This review aims to provide a comprehensive view of salt stress effects on underground vegetable crops at different levels of biological organization and discuss the underlying salt tolerance mechanisms. Also, the role of multi-omics in dissecting gene and protein regulatory networks involved in salt tolerance mechanisms is highlighted, which can potentially help in breeding salt-tolerant underground vegetable crops.

Nanopotassium, Nanosilicon, and Biochar Applications Improve Potato Salt Tolerance by Modulating Photosynthesis, Water Status, and Biochemical Constituents

Salinity is one of the main environmental stresses, and it affects potato growth and productivity in arid and semiarid regions by disturbing physiological process, such as the photosynthesis rate, the absorption of essential nutrients and water, plant hormonal functions, and vital metabolic pathways. Few studies are available on the application of combined nanomaterials to mitigate salinity stress on potato plants (Solanum tuberosum L. cv. Diamont). In order to assess the effects of the sole or combined application of silicon (Si) and potassium (K) nanoparticles and biochar (Bc) on the agro-physiological properties and biochemical constituents of potato plants grown in saline soil, two open-field experiments were executed on a randomized complete block design (RCBD), with five replicates. The results show that the biochar application and nanoelements (n-K and n-Si) significantly improved the plant heights, the fresh and dry plant biomasses, the numbers of stems/plant, the leaf relative water content, the leaf chlorophyll content, the photosynthetic rate (Pn), the leaf stomatal conductance (Gc), and the tuber yields, compared to the untreated potato plants (CT). Moreover, the nanoelements and biochar improved the content of the endogenous elements of the plant tissues (N, P, K, Mg, Fe, Mn, and B), the leaf proline, and the leaf gibberellic acid (GA3), in addition to reducing the leaf abscisic acid content (ABA), the activity of catalase (CAT), and the peroxidase (POD) and polyphenol oxidase (PPO) in the leaves of salt-stressed potato plants. The combined treatment achieved maximum plant growth parameters, physiological parameters, and nutrient concentrations, and minimum transpiration rates (Tr), leaf abscisic acid content (ABA), and activities of the leaf antioxidant enzymes (CAT, POD, and PPO). Furthermore, the combined treatment also showed the highest tuber yield and tuber quality, including the contents of carbohydrates, proteins, and the endogenous nutrients of the tuber tissues (N, P, and K), and the lowest starch content. Moreover, Pearson’s correlation showed that the plant growth and the tuber yields of potato plants significantly and positively correlated with the photosynthesis rate, the internal CO2 concentration, the relative water content, the proline, the chlorophyll content, and the GA3, and that they were negatively correlated with the leaf Na content, PPO, CAT, ABA, MDA, and Tr. It might be concluded that nanoelement (n-K and n-Si) and biochar applications are a promising method to enhance the plant growth and crop productivity of potato plants grown under salinity conditions.

Interactions of nanoparticles and salinity stress at physiological, biochemical and molecular levels in plants: A review

Salinity stress is one of the most destructive non-biological stresses in plants that has adversely affected many agricultural lands in the world. Salinity stress causes many morphological, physiological, epigenetic and genetic changes in plants by increasing sodium and chlorine ions in the plant cells. The plants can alleviate this disorder to some extent through various mechanisms and return the cell to its original state, but if the salt dose is high, the plants may not be able to provide a proper response and can die due to salt stress. Nowadays, scientists have offered many solutions to this problem. Nanotechnology is one of the most emerging and efficient technologies that has been entered in this field and has recorded very brilliant results. Although some studies have confirmed the positive effects of nontechnology on plants under salinity stress, there is no the complete understanding of the relationship and interaction of nanoparticles and intracellular mechanisms in the plants. In the review paper, we have tried to reach a conclusion from the latest articles that how NPs could help salt-stressed plants to recover their cells under salt stress so that we can take a step towards clearing the existing ambiguities for researchers in this field.

Enhancing Salt Tolerance in Soybean by Exogenous Boron: Intrinsic Study of the Ascorbate-Glutathione and Glyoxalase Pathways

Boron (B) performs physiological functions in higher plants as an essential micronutrient, but its protective role in salt stress is poorly understood. Soybean (Glycine max L.) is planted widely throughout the world, and salinity has adverse effects on its physiology. Here, the role of B (1 mM boric acid) in salt stress was studied by subjecting soybean plants to two levels of salt stress: mild (75 mM NaCl) and severe (150 mM NaCl). Exogenous B relieved oxidative stress by enhancing antioxidant defense system components, such as ascorbate (AsA) levels, AsA/dehydroascorbate ratios, glutathione (GSH) levels, the GSH and glutathione disulfide ratios, and ascorbate peroxidase, monodehydroascorbate reductase, and dehydroascorbate reductase activities. B also enhanced the methylglyoxal detoxification process by upregulation of the components of the glyoxalase system in salt-stressed plants. Overall, B supplementation enhanced antioxidant defense and glyoxalase system components to alleviate oxidative stress and MG toxicity induced by salt stress. B also improved the physiology of salt-affected soybean plants.

Effect of New Pre-Emergence Herbicides on Quality and Yield of Potato and Its Associated Weeds

Potato is an economically important vegetable crop in Egypt. Weed infestation, especially broad-leafed, during the vegetative growth stage substantially affects both crop yield and tuber quality. In the current study, the impact of new ready-mix pre-emergent herbicides on broadleaf weeds, tuber yield, and quality was evaluated. The two-year field experiment comprised the following treatments: (1) Un-weeded control, (2) Hand hoeing, (3) Sencor, (4) Ecopart, (5) Zeus, (6) Kroki, and (7) Flomex. The results showed that weed control treatments significantly reduced the weed density compared to un-weeded control and the herbicides efficacy reached over 90%. The herbicidal treatments also significantly increased the activity of antioxidant enzymes peroxidases (POX) and catalase (CAT) and improved the non-enzymatic antioxidant (carotenoids) compared to un-weeded control. Conversely, the higher content of malondialdehyde (MDA) in potato leaves was obtained for un-weeded control. Moreover, weed control treatments caused significant enhancement in plant growth parameters, yield, and its components in addition to tuber quality of potato. Compared to the un-weeded control, maximum tuber yield was observed in Flomex followed by Ecopart, Kroki, Zeus, and Sencor, respectively. The higher number of tubers and total yield were recorded in plants treated with Flomex plus compared to all the other treatments. Higher content of total soluble sugar, total soluble protein, and total starch content was observed in weed control treatments compared with un-weeded control. Based on Pearson’s correlation and heatmap analysis, the changes in agro-physiological parameters data are linked to the herbicidal treatments. The results indicate that the applied herbicides could be alternative products for Sencor and an option for controlling broadleaved weeds. However, further studies are needed to ensure their efficacy and safety under other conditions.

Coping with the Challenges of Abiotic Stress in Plants: New Dimensions in the Field Application of Nanoparticles

Abiotic stress in plants is a crucial issue worldwide, especially heavy-metal contaminants, salinity, and drought. These stresses may raise a lot of issues such as the generation of reactive oxygen species, membrane damage, loss of photosynthetic efficiency, etc. that could alter crop growth and developments by affecting biochemical, physiological, and molecular processes, causing a significant loss in productivity. To overcome the impact of these abiotic stressors, many strategies could be considered to support plant growth including the use of nanoparticles (NPs). However, the majority of studies have focused on understanding the toxicity of NPs on aquatic flora and fauna, and relatively less attention has been paid to the topic of the beneficial role of NPs in plants stress response, growth, and development. More scientific attention is required to understand the behavior of NPs on crops under these stress conditions. Therefore, the present work aims to comprehensively review the beneficial roles of NPs in plants under different abiotic stresses, especially heavy metals, salinity, and drought. This review provides deep insights about mechanisms of abiotic stress alleviation in plants under NP application.

Cerium oxide nanoparticles improve cotton salt tolerance by enabling better ability to maintain cytosolic K+/Na+ ratio

Background

Salinity is a worldwide factor limiting the agricultural production. Cotton is an important cash crop; however, its yield and product quality are negatively affected by soil salinity. Use of nanomaterials such as cerium oxide nanoparticles (nanoceria) to improve plant tolerance to stress conditions, e.g. salinity, is an emerged approach in agricultural production. Nevertheless, to date, our knowledge about the role of nanoceria in cotton salt response and the behind mechanisms is still rare.

Results

We found that PNC (poly acrylic acid coated nanoceria) helped to improve cotton tolerance to salinity, showing better phenotypic performance, higher chlorophyll content (up to 68% increase) and biomass (up to 38% increase), and better photosynthetic performance such as carbon assimilation rate (up to 144% increase) in PNC treated cotton plants than the NNP (non-nanoparticle control) group. Under salinity stress, in consistent to the results of the enhanced activities of antioxidant enzymes, PNC treated cotton plants showed significant lower MDA (malondialdehyde, up to 44% decrease) content and reactive oxygen species (ROS) level such as hydrogen peroxide (H₂O₂, up to 79% decrease) than the NNP control group, both in the first and second true leaves. Further experiments showed that under salinity stress, PNC treated cotton plants had significant higher cytosolic K⁺ (up to 84% increase) and lower cytosolic Na⁺ (up to 77% decrease) fluorescent intensity in both the first and second true leaves than the NNP control group. This is further confirmed by the leaf ion content analysis, showed that PNC treated cotton plants maintained significant higher leaf K⁺ (up to 84% increase) and lower leaf Na⁺ content (up to 63% decrease), and thus the higher K⁺/Na⁺ ratio than the NNP control plants under salinity stress. Whereas no significant increase of mesophyll cell vacuolar Na⁺ intensity was observed in PNC treated plants than the NNP control under salinity stress, suggesting that the enhanced leaf K⁺ retention and leaf Na⁺ exclusion, but not leaf vacuolar Na⁺ sequestration are the main mechanisms behind PNC improved cotton salt tolerance. qPCR results showed that under salinity stress, the modulation of HKT1 but not SOS1 refers more to the PNC improved cotton leaf Na⁺ exclusion than the NNP control.

Conclusions

PNC enhanced leaf K⁺ retention and Na⁺ exclusion, but not vacuolar Na⁺ sequestration to enable better maintained cytosolic K⁺/Na⁺ homeostasis and thus to improve cotton salt tolerance. Our results add more knowledge for better understanding the complexity of plant-nanoceria interaction in terms of nano-enabled plant stress tolerance.

Graphic abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-021-00892-7.

Assessment of Morpho-Physiological, Biochemical and Antioxidant Responses of Tomato Landraces to Salinity Stress

Understanding salt tolerance in tomato (Solanum lycopersicum L.) landraces will facilitate their use in genetic improvement. The study assessed the morpho-physiological variability of Hail tomato landraces in response to different salinity levels at seedling stages and recommended a tomato salt-tolerant landrace for future breeding programs. Three tomato landraces, Hail 548, Hail 747, and Hail 1072 were tested under three salinity levels: 75, 150, and 300 mM NaCl. Salinity stress reduced shoots' fresh and dry weight by 71% and 72%, and roots were 86.5% and 78.6%, respectively. There was 22% reduced chlorophyll content, carotene content by 18.6%, and anthocyanin by 41.1%. Proline content increased for stressed treatments. The 300 mM NaCl treatment recorded the most proline content increases (67.37 mg/g fresh weight), with a percent increase in proline reaching 61.67% in Hail 747. Superoxide dismutase (SOD) activity decreased by 65% in Hail 548, while it relatively increased in Hail 747 and Hail 1072 treated with 300 mM NaCl. Catalase (CAT) activity was enhanced by salt stress in Hail 548 and recorded 7.6%, increasing at 75 and 5.1% at 300 mM NaCl. It revealed a reduction in malondialdehyde (MDA) at the 300 mM NaCl concentration in both Hail 548 and Hail 1072 landraces. Increasing salt concentrations showed a reduction in transpiration rate of 70.55%, 7.13% in stomatal conductance, and 72.34% in photosynthetic rate. K+/Na+ ratios decreased from 56% for 75 mM NaCl to 85% for 300 mM NaCl treatments in all genotypes. The response to salt stress in landraces involved some modifications in morphology, physiology, and metabolism. The landrace Hail 548 may have better protection against salt stress and observed protection against reactive oxygen species (ROS) by increasing enzymatic "antioxidants" activity under salt stress.

ROS Homeostasis and Plant Salt Tolerance: Plant Nanobiotechnology Updates

Salinity is an issue impairing crop production across the globe. Under salinity stress, besides the osmotic stress and Na+ toxicity, ROS (reactive oxygen species) overaccumulation is a secondary stress which further impairs plant performance. Chloroplasts, mitochondria, the apoplast, and peroxisomes are the main ROS generation sites in salt-stressed plants. In this review, we summarize ROS generation, enzymatic and non-enzymatic antioxidant systems in salt-stressed plants, and the potential for plant biotechnology to maintain ROS homeostasis. Overall, this review summarizes the current understanding of ROS homeostasis of salt-stressed plants and highlights potential applications of plant nanobiotechnology to enhance plant tolerance to stresses.

Agro-Nanotechnology as an Emerging Field: A Novel Sustainable Approach for Improving Plant Growth by Reducing Biotic Stress

In the present era, the global need for food is increasing rapidly; nanomaterials are a useful tool for improving crop production and yield. The application of nanomaterials can improve plant growth parameters. Biotic stress is induced by many microbes in crops and causes disease and high yield loss. Every year, approximately 20–40% of crop yield is lost due to plant diseases caused by various pests and pathogens. Current plant disease or biotic stress management mainly relies on toxic fungicides and pesticides that are potentially harmful to the environment. Nanotechnology emerged as an alternative for the sustainable and eco-friendly management of biotic stress induced by pests and pathogens on crops. In this review article, we assess the role and impact of different nanoparticles in plant disease management, and this review explores the direction in which nanoparticles can be utilized for improving plant growth and crop yield.

Nanoparticles potentially mediate salt stress tolerance in plants

In the era of climate change, salt stress is a promising threat to agriculture, limiting crop production via imposing primary effects such as osmotic and ionic, as well as secondary effects such as oxidative stress, perturbance in hormonal homeostasis, and nutrient imbalance. On the other hand, production areas are expanding into the salt affected regions due to excessive pressure for fulfilling food security targets to meet the needs of continuously increasing human population. Accumulating evidences demonstrate that supplementation of nanoparticles to plants can significantly alleviate the injurious effects caused by various harsh conditions including salt stress, and hence, regulate adaptive mechanisms in plants. Various types of NPs and nanofertilizers have shown a promising evidence so far regarding salt stress management. In this review, we recapitulate recent pioneering progress made towards acquiring salt stress tolerance in crop plants utilizing NPs. Finally, future research directions in this domain to explicate the comprehensive roles of nanoparticles in improving salt tolerance in plants are underscored. To ensure social acceptance and safe use of NPs, some conclusive directions have been elaborated in order to achieve sustainable progress in crop production under saline environments.

Foliar fertigation of ascorbic acid and zinc improves growth, antioxidant enzyme activity and harvest index in barley (Hordeum vulgare L.) grown under salt stress

Crop productivity is limited by several environmental constraints. Among these, salt stress plays a key role in limiting the growth and yield production of economically important agricultural crops. However, the exogenous fertigation of vitamins and minerals could serve as a "shot-gun" approach for offsetting the deleterious effects of salts present in the rhizosphere. Therefore, an experiment was conducted to quantify the efficacy of foliar fertigation of ascorbic acid (vitamin-C) and zinc (Zn) on the physio-biochemical attributes of barley (Hordeum vulgare L. Genotype B-14011) grown in a saline environment. The salt stress resulted in a reduced biological yield associated with a decrease in chlorophyll pigment, while a significant enhancement in Na⁺ and Zn²⁺ was observed under salinity stress. Similarly, the contents of total soluble proteins, total free amino acids, lipid peroxidation, and H₂O₂ and the activities of antioxidative enzymes (SOD, POD, CAT, APX and proline) were significantly enhanced under salinity stress. Moreover, salinity negatively affected the yield attributes and ion uptake of plants. However, foliar fertigation with AsA +0.03% Zn enhanced vegetative growth, photosynthetic pigments, synchronized ion uptake, the synthesis of enzymatic and non-enzymatic antioxidants, and the harvest index. It is inferred from this study that among all treatments, the effect of foliar fertigation with the AsA+0.03% Zn combination not only improved the salt stress tolerance but also improved the yield attributes, which will aid in the improvement in barley seed yield and is a step to solve the problem of malnutrition through biofortification of vitamin-C and zinc.

Zinc and Paclobutrazol Mediated Regulation of Growth, Upregulating Antioxidant Aptitude and Plant Productivity of Pea Plants under Salinity

Soil salinity is the main obstacle to worldwide sustainable productivity and food security. Zinc sulfate (Zn) and paclobutrazol (PBZ) as a cost-effective agent, has multiple biochemical functions in plant productivity. Meanwhile, their synergistic effects on inducing salt tolerance are indecisive and not often reported. A pot experiment was done for evaluating the defensive function of Zn (100 mg/L) or PBZ (200 mg/L) on salt (0, 50, 100 mM NaCl) affected pea plant growth, photosynthetic pigment, ions, antioxidant capacity, and yield. Salinity stress significantly reduces all growth and yield attributes of pea plants relative to nonsalinized treatment. This reduction was accompanied by a decline in chlorophyll, nitrogen, phosphorus, and potassium (K⁺), the ratio between K⁺ and sodium (Na⁺), as well as reduced glutathione (GSH) and glutathione reductase (GR). Alternatively, salinity increased Na⁺, carotenoid (CAR), proline (PRO), ascorbic acid (AsA), superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) over nonsalinized treatment. Foliar spraying with Zn and PBZ under normal condition increased plant growth, nitrogen, phosphorus, potassium, K⁺/Na⁺ ratio, CAR, PRO, AsA, GSH, APX, GR, and yield and its quality, meanwhile decreased Na⁺ over nonsprayed plants. Application of Zn and PBZ counteracted the harmful effects of salinity on pea plants, by upregulating the antioxidant system, ion homeostasis, and improving chlorophyll biosynthesis that induced plant growth and yield components. In conclusion, Zn plus PBZ application at 30 and 45 days from sowing offset the injuries of salinity on pea plant growth and yield by upregulating the antioxidant capacity and increasing photosynthetic pigments.