Ameliorating Drought Effects in Wheat Using an Exclusive or Co-Applied Rhizobacteria and ZnO Nanoparticles

Engineered Nanomaterials Enhance Crop Drought Resistance for Sustainable Agriculture

Nanotechnology has emerged as a promising strategy for enhancing crop resilience to extreme weather events induced by climate change, such as drought. However, the potential of nanomaterials (NMs) to mitigate drought-induced stress remains insufficiently understood. Here, we conducted a meta-analysis to quantify the effects of NMs on crop growth and yield under drought. Our findings reveal that NMs significantly improved crop growth under drought, with a more pronounced positive impact on C3 than C4 crops. Furthermore, seed application of NMs exhibits more significant potential in protecting crops than root or foliar applications. Specifically, NMs increased the relative water content and water use efficiency of crops by 10.8 and 33.3%, respectively. The potential of NMs to enhance the drought resistance was associated with improving the photosynthetic process, increasing osmolyte accumulation, enhancing nutrient uptake, and alleviating oxidative damage. This analysis raises the potential of nanotechnology as a significant tool for sustainable nano-enabled agriculture in a changing climate.

Effect of selenium and compost on physiological, biochemical, and productivity of chili under chromium stress

In the era of industrialization, chromium (Cr) as a metal poses a substantial threat to the ecosystem. Selenium (Se) is essential for minimizing heavy metal stress in crops and effectively reducing their accumulation in edible plant parts. This research work aimed to evaluate the synergistic effect of compost and Se for alleviation of Cr stress in chili plants. A greenhouse trail was conducted to investigate the individual and combined effects of foliage applied selenium (Na2SeO4 = 3 µM) and soil applied compost (250 mg kg-1, w/w) on the growth, physio-biochemical, antioxidant and of chili grown under varying levels of induced Cr stress (0, 100, and 200 mg kg-1 using K2Cr2O7). Findings revelaed that a significant linear reduction was observed in growth, biomass, and physiological parameters of chili plant with an increasing level of Cr concentrations. Maximum decrease in relative water content (20.04 and 27.21%) and total chlorophyll concentrations (11.73 and 20.57%) and increased in electrolyte leakage (59.14 and 130.52%) was observed at 100 and 200 mg kg-1 of Cr levels in soil in comparison with the control, respectively. Combined application of compost and selenium showed significant increase regardless of Cr concentrations in the soil. Synergistic approach of compost and selenium showed improved growth in comparison with the sole application in limiting the movement and uptake of Cr in the roots and fruits of chili plants. Moreover, improved physiological and antioxidant potential of chili plants helped to cope with higher levels of Cr stress by limiting the lipid peroxidation and membrane damange. The combined use of compost and selenium induces the physio-biochemical defense responses against of the varying levels of Cr stress in chili plants. This promising approach highlights the significant potential for growing chili crop in Cr-contaminated soils to achieve better quality and higher yields.

ZnO-nanoparticles and stage-based drought tolerance in wheat (Triticum aestivum L.): effect on morpho-physiology, nutrients uptake, grain yield and quality

Drought-stressed and zinc-deficient soils are major contributors to reduced wheat yields and low-quality grains, especially in semi-arid regions of the world. Zinc-oxide nanoparticles (ZnO-NPs) are adept enough to avoid these losses if applied under the right dose at the right growth stage of many crops including wheat (Triticum aestivum L.). Therefore, a pot experiment was conducted with four levels of ZnO-NPs (0, 50, 100 and 150 ppm), and drought imposed at tillering (D1) and grain filling (D2) stages, considering normal irrigation as control (D0), to explore interactive effects of ZnO-NPs and drought episodes on growth, eco-physiology, yield, and grain quality of wheat. The results depicted dose and growth stage-dependent variations in all recorded parameters. ZnO-NPs (150 ppm) significantly increased the number of grains (12.5%), grain weight (12.4%), total yield (25.5%), and zinc contents (58.6%) when the crop was exposed to drought stress at tillering stage, compared to the control treatment. Likewise, drought at grain filling stage with ZnO-NPs (150 ppm) significantly enhanced plant height, spike length, biomass, zinc contents, and grain protein by 15.5%, 3.2%, 16.7%, 100.0%, and 53.8%, respectively, when compared with control treatment. Thus, ZnO-NPs emerged as a potential drought alleviator and yield-oriented safe nano-fertilizer for wheat in semi-arid regions facing irrigation challenges.

In-vitro antifungal potential of myco versus bacteria synthesized ZnO NPs against chickpea and apricot pathogen

Chickpea (Cicer arietinum) and Apricot (Prunus armeniaca) both are economically and nutritionally important, these both faces severe losses due to fungal Infections. For several fungal infections, traditional methods of management rely on chemical fungicideswhich have environmental and health risks. The in-vitro antifungal efficacy of myco-synthesized and bacteria-synthesized zinc oxide (ZnO) nanoparticles against pathogens impacting chickpea and apricot is aimed to be compared in this review article. Evaluated for their antifungal effectiveness against Fusarium oxysporum f. sp. ciceris in chickpea and Alternaria solani, myco-synthesized ZnO NPs generated from Trichoderma harzianum and bacteria-synthesized ZnO NPs were using a poisoned food approach, the study evaluated minimum inhibitory concentration (MIC), minimum fungicidal concentration (MFC), and inhibition zone diameter. At lower concentrations, myco-synthesized ZnO NPs shown better antifungal activity than their bacteria-synthesized counterparts, according to results. Surface changes, size, and concentration of nanoparticles were main determinants of antifungal activity. Emphasizing the need of more study to maximize the synthesis and application in agricultural environments, this review underlines the possibilities of ZnO NPs as sustainable substitutes for chemical fungicides.

Comparative transcriptome reveals lignin biosynthesis being the key molecular pathway regulating oilseed rape growth treated by SiO2 NPs and biochar

Biochar and SiO2 NPs are effective soil conditioners, but the impacts and mechanisms of combined application in oilseed rape are not yet clear. Therefore, an experiment was designed to investigate oilseed rape growth, physiological indexes, and transcriptome sequencing under four treatments: control (CK), Platanus orientalis L. leaf biochar (B), SiO2 NPs (S), and BS. Our results showed that B, S and BS treatments all promoted the root growth, root activity and biomass of oilseed rape, especially the root length and fresh weight in BS, which were increased by 77.48% and 279.07%, respectively. Moreover, the three-dimensional fluorescence spectra of B and BS were similar, and the tyrosine-like substance proportion in B, S and BS increased from 7.8 to 9.4%, 10.2% and 19.5%, respectively. In transcriptome analysis, there were 10,280 differentially expressed genes (DEGs) shared in B and BS, 3431 DEGs shared in S and BS, and 2815 DEGs shared in B, S and BS. We also found that B, S and BS all regulated oilseed rape growth by inducing the lignin biosynthesis and the relevant genes encoding BBE-like, BGL, UDP in the phenylpropanoid biosynthesis pathway. The results provide gene regulation associated with the phenylpropanoid biosynthesis applying the biochar and SiO2 NPs, which can be used to increase biomass.

Green synthesis and characterization of magnetite nanoparticles using Eucalyptus globulus leaves for water treatment and agronomic valorization

This work presents a new process, based on the green nanoparticles Fe3O4 and magnetization coupling for the treatment of saline well water. In this context, iron nanoparticles were synthesized using Eucalyptus globulus leaves. The nanomaterials were characterized by scanning electron microscopy and infrared for identification. Batch experiments were conducted to illustrate the optimal parameters related to contact times and the mass of nanoparticles. The latter marked an optimal contact time of 100 min and a mass of 56 mg/L accompanied by a magnetic treatment for a contact time of 48 min. The results showed a significant (R2 = 0.93) water salinity reduction (67%) and a potential for improvement in the germination of tomato seeds (81%) through the investigation of the evolution of the length of the roots, the stems, and the number of germinated seeds.

Cu-nanoparticles enhance the sustainable growth and yield of drought-subjected wheat through physiological progress

Drought stress (DS) is a significant abiotic stress that limits agricultural productivity worldwide. In semi-arid climates, one potential solution to alleviate the deleterious effects of drought is the use of soil amendments such as nanoparticles. The current research was conducted out to probe the sway of drought at critical growth stages (CGS) of wheat crop (D0: Control, D1: Drought at tillering stage, and D2: Drought at anthesis stage) and the application of Cu-nanoparticles (T0: 0 mg L-1, T1: 300 mg L-1, T2: 700 mg L-1, and T3: 950 mg L-1) in order to improve drought resilience. Results of the study revealed that DS considerably decreased the wheat growth and yield during CGS. However, Cu-nanoparticles application alleviated the detrimental backlash of DS and led to improvements in various aspects of wheat growth and yield, including plant height, spike length, 1000 grain weight, stomatal conductance, leaf chlorophyll content, water use efficiency, leaf turgor potential, relative water content, and ultimately the grain yield. The use of principal component analysis allowed us to integrate and interpret the diverse findings of our study, elucidating the impact of Cu-nanoparticle treatment on wheat growth and yield under drought. Overall, the study concluded that DS during the anthesis stage had the most significant negative impact on crop yield. However, applying Cu-nanoparticles at the rate of 300 mg L-1 proved to be an effective strategy for improving crop productivity by reducing the harmful effects of drought.

Advancement of metal oxide nanomaterials on agri-food fronts

The application of metal oxide nanomaterials (MOx NMs) in the agrifood industry offers innovative solutions that can facilitate a paradigm shift in a sector that is currently facing challenges in meeting the growing requirements for food production, while safeguarding the environment from the impacts of current agriculture practices. This review comprehensively illustrates recent advancements and applications of MOx for sustainable practices in the food and agricultural industries and environmental preservation. Relevant published data point out that MOx NMs can be tailored for specific properties, enabling advanced design concepts with improved features for various applications in the agrifood industry. Applications include nano-agrochemical formulation, control of food quality through nanosensors, and smart food packaging. Furthermore, recent research suggests MOx's vital role in addressing environmental challenges by removing toxic elements from contaminated soil and water. This mitigates the environmental effects of widespread agrichemical use and creates a more favorable environment for plant growth. The review also discusses potential barriers, particularly regarding MOx toxicity and risk evaluation. Fundamental concerns about possible adverse effects on human health and the environment must be addressed to establish an appropriate regulatory framework for nano metal oxide-based food and agricultural products.

Unraveling the contribution of copper seed priming in enhancing chromium tolerance in wheat by improving germination, growth, and grain yield

Exposure to chromium (Cr) on farmlands drastically restricts the growth and productivity of cereal crops, including wheat (Triticum aestivum L.). Utilizing micronutrients, the seed-priming strategy is crucial to preventing the adverse consequences of Cr-stress. Nevertheless, additional investigation needs to be conducted to figure out whether Cu-priming remedies are beneficial for wheat experiencing Cr-stress. The objective of this study was to ascertain the contribution of Cu-treated seed priming in the mitigation of detrimental impacts of Cr-stress on wheat germination, growth, and production. Two wheat cultivars, Dilkash-20 and Subhani-21, were subjected to seed priming treatments (0 mg/L, 0.1 mg/L, and 1.0 mg/L) of Cu under Cr-stress levels (200 mg/kg) in two successive experiments, respectively, petri-dish and soil-filled pot experiments. The Cu-priming significantly enhanced the wheat seed germination, plant growth, and grain yield under Cr-stress. Cu priming improved enzyme activities such as glutathione peroxidase (14.60, 16.30%), superoxide dismutase (62.55, 115.21%), peroxidase, catalase (78.39, 80.23%), ascorbate peroxidase(17.72, 20.32%), and key primary and secondary metabolites such as proline (54.19, 81.27%), glycine betaine (40.13, 79.39%), total soluble proteins (47.92, 51.58%), phenolics (40.05, 18.61%), and flavonoids (56.90, 113.46%), respectively, of Dilkash-20 and Subhani-21 under Cr-stress. The outcome of our investigation underscored the efficacy of Cu-priming treatments (0.1 mg/L and 1.0 mg/L) in Cr-stress circumstances to augment wheat germination, growth, and grain yield.

Seed priming with selenium improves growth and yield of quinoa plants suffering drought

Drought stress is a worldwide threat to the productivity of crops, especially in arid and semi-arid zones of the world. In the present study, the effect of selenium (Se) seed priming on the yield of quinoa under normal and drought conditions was investigated. A pot trial was executed to enhance the drought tolerance in quinoa by Se seed priming (0, 3, 6, and 9 mg Se L-1). The plants were exposed to water stress at three different growth stages of quinoa, viz. multiple leaf, flowering, and seed filling. It was noticed that drought significantly affected the yield components of quinoa, however, Se priming improved the drought tolerance potential and yield of quinoa by maintaining the plant water status. Se priming significantly increased main panicle length (20.29%), main panicle weight (26.43%), and thousand grain weight (15.41%) as well as the gas exchange parameters (transpiration rate (29.74%), stomatal conductance (35.29%), and photosynthetic rate (28.79%), total phenolics (29.36%), leaf chlorophyll contents (35.97%), water relations (leaf relative water contents (14.55%), osmotic potential (10.32%), water potential (38.35%), and turgor potential (31.37%), and economic yield (35.99%) under drought stress. Moreover, Se priming markedly improved grain quality parameters i.e., phosphorus, potassium, and protein contents by 21.28%, 18.92%, and 15.04%, respectively. The principal component analysis connected the various study scales and showed the ability of physio-biochemical factors to describe yield fluctuations in response to Se seed priming under drought conditions. In conclusion, a drought at the seed-filling stage has a far more deleterious impact among other critical growth stages and seed priming with Se (6 mg L-1) was found more effective in alleviating the detrimental effects of drought on the grain yield of quinoa.

Unveiling the Potential of Bioinoculants and Nanoparticles in Sustainable Agriculture for Enhanced Plant Growth and Food Security

The increasing public concern over the negative impacts of chemical fertilizers and pesticides on food security and sustainability has led to exploring innovative methods that offer both environmental and agricultural benefits. One such innovative approach is using plant-growth-promoting bioinoculants that involve bacteria, fungi, and algae. These living microorganisms are applied to soil, seeds, or plant surfaces and can enhance plant development by increasing nutrient availability and defense against plant pathogens. However, the application of biofertilizers in the field faced many challenges and required conjunction with innovative delivering approaches. Nanotechnology has gained significant attention in recent years due to its numerous applications in various fields, such as medicine, drug development, catalysis, energy, and materials. Nanoparticles with small sizes and large surface areas (1-100 nm) have numerous potential functions. In sustainable agriculture, the development of nanochemicals has shown promise as agents for plant growth, fertilizers, and pesticides. The use of nanomaterials is being considered as a solution to control plant pests, including insects, fungi, and weeds. In the food industry, nanoparticles are used as antimicrobial agents in food packaging, with silver nanomaterials being particularly interesting. However, many nanoparticles (Ag, Fe, Cu, Si, Al, Zn, ZnO, TiO2, CeO2, Al2O3, and carbon nanotubes) have been reported to negatively affect plant growth. This review focuses on the effects of nanoparticles on beneficial plant bacteria and their ability to promote plant growth. Implementing novel sustainable strategies in agriculture, biofertilizers, and nanoparticles could be a promising solution to achieve sustainable food production while reducing the negative environmental impacts.

Effects of Salicylic Acid and Macro- and Micronutrients through Foliar and Soil Applications on the Agronomic Performance, Physiological Attributes, and Water Productivity of Wheat under Normal and Limited Irrigation in Dry Climatic Conditions

Ensuring food security with severe shortages of freshwater and drastic changes in climatic conditions in arid countries requires the urgent development of feasible and user-friendly strategies. Relatively little is known regarding the impacts of the co-application (Co-A) of salicylic acid (SA), macronutrients (Mac), and micronutrients (Mic) through foliar (F) and soil (S) application strategies on field crops under arid and semiarid climatic conditions. A two-year field experiment was designed to compare the impacts of seven (Co-A) treatments of this strategy, including a control, F_{SA + Mic}, F_{SA + Mac}, S_SA + F_Mic, S_SA + F_{SA + Mic}, S_{SA + Mic} + F_SA, and S_{SA + Mic} + F_{Mac + Mic} on the agronomic performance, physiological attributes, and water productivity (WP) of wheat under normal (NI) and limited (LMI) irrigation conditions. The results reveal that the LMI treatment caused a significant reduction in various traits related to the growth (plant height, tiller and green leaf numbers, leaf area index, and shoot dry weight), physiology (relative water content and chlorophyll pigments), and yield components (spike length, grain weight and grain numbers per spike, thousand-grain weight, and harvest index) of wheat by 11.4-47.8%, 21.8-39.8%, and 16.4-42.3%, respectively, while WP increased by 13.3% compared to the NI treatment. The different Co-A treatments have shown a 0.2-23.7%, 3.6-26.7%, 2.3-21.6%, and 12.2-25.0% increase in various traits related to growth, physiology, yield, and WP, respectively, in comparison to the control treatment. The S_SA+ F_{SA + Mic} was determined as the best treatment that achieved the best results for all studied traits under both irrigation conditions, followed by F_{SA + Mic} and S_{SA + Mic} + F_SA under LMI in addition to F_{SA + Mac} under NI conditions. It can be concluded that the Co-A of essential plant nutrients along with SA accomplished a feasible, profitable, and easy-to-use strategy to attenuate the negative impacts of deficit irrigation stress, along with the further improvement in the growth and production of wheat under NI conditions.

Molecular Mechanisms Determining the Role of Bacteria from the Genus Azospirillum in Plant Adaptation to Damaging Environmental Factors

Agricultural plants are continuously exposed to environmental stressors, which can lead to a significant reduction in yield and even the death of plants. One of the ways to mitigate stress impacts is the inoculation of plant growth-promoting rhizobacteria (PGPR), including bacteria from the genus Azospirillum, into the rhizosphere of plants. Different representatives of this genus have different sensitivities or resistances to osmotic stress, pesticides, heavy metals, hydrocarbons, and perchlorate and also have the ability to mitigate the consequences of such stresses for plants. Bacteria from the genus Azospirillum contribute to the bioremediation of polluted soils and induce systemic resistance and have a positive effect on plants under stress by synthesizing siderophores and polysaccharides and modulating the levels of phytohormones, osmolytes, and volatile organic compounds in plants, as well as altering the efficiency of photosynthesis and the antioxidant defense system. In this review, we focus on molecular genetic features that provide bacterial resistance to various stress factors as well as on Azospirillum-related pathways for increasing plant resistance to unfavorable anthropogenic and natural factors.

Synergistic impact of nanomaterials and plant probiotics in agriculture: A tale of two-way strategy for long-term sustainability

Modern agriculture is primarily focused on the massive production of cereals and other food-based crops in a sustainable manner in order to fulfill the food demands of an ever-increasing global population. However, intensive agricultural practices, rampant use of agrochemicals, and other environmental factors result in soil fertility degradation, environmental pollution, disruption of soil biodiversity, pest resistance, and a decline in crop yields. Thus, experts are shifting their focus to other eco-friendly and safer methods of fertilization in order to ensure agricultural sustainability. Indeed, the importance of plant growth-promoting microorganisms, also determined as "plant probiotics (PPs)," has gained widespread recognition, and their usage as biofertilizers is being actively promoted as a means of mitigating the harmful effects of agrochemicals. As bio-elicitors, PPs promote plant growth and colonize soil or plant tissues when administered in soil, seeds, or plant surface and are used as an alternative means to avoid heavy use of agrochemicals. In the past few years, the use of nanotechnology has also brought a revolution in agriculture due to the application of various nanomaterials (NMs) or nano-based fertilizers to increase crop productivity. Given the beneficial properties of PPs and NMs, these two can be used in tandem to maximize benefits. However, the use of combinations of NMs and PPs, or their synergistic use, is in its infancy but has exhibited better crop-modulating effects in terms of improvement in crop productivity, mitigation of environmental stress (drought, salinity, etc.), restoration of soil fertility, and strengthening of the bioeconomy. In addition, a proper assessment of nanomaterials is necessary before their application, and a safer dose of NMs should be applicable without showing any toxic impact on the environment and soil microbial communities. The combo of NMs and PPs can also be encapsulated within a suitable carrier, and this method aids in the controlled and targeted delivery of entrapped components and also increases the shelf life of PPs. However, this review highlights the functional annotation of the combined impact of NMs and PPs on sustainable agricultural production in an eco-friendly manner.

Melatonin: Current status and future perspectives in horticultural plants

Global warming in this century increases incidences of various abiotic stresses, restricting plant growth and productivity and posing a severe threat to global food production and security. Different phytohormones are produced by plants to mitigate the adverse effects of these stresses. One such phytohormone is melatonin (MEL), which, being a potential bio-stimulator, helps to govern a wide array of functions in horticultural crops. Recent advancements have determined the role of MEL in plants' responses to abiotic stresses. MEL enhances physiological functions such as seed germination, growth and development, seedling growth, root system architecture, and photosynthetic efficiency. The potential function of MEL in stressful environments is to regulate the enzymatic and non-enzymatic antioxidant activity, thus playing a role in the substantial scavenging of reactive oxygen species (ROS). Additionally, MEL, as a plant growth regulator and bio-stimulator, aids in promoting plant tolerance to abiotic stress, mainly through improvements in nutrient uptake, osmolyte production, and cellular membrane stability. This review, therefore, focuses on the possible functions of MEL in the induction of different abiotic stresses in horticultural crops. Therefore, this review would help readers learn more about MEL in altered environments and provide new suggestions on how this knowledge could be used to develop stress tolerance.

Appropriate Application Methods for Salicylic Acid and Plant Nutrients Combinations to Promote Morpho-Physiological Traits, Production, and Water Use Efficiency of Wheat under Normal and Deficit Irrigation in an Arid Climate

Freshwater shortage and inadequate nutrient management are the two major challenges for sustainable wheat production in arid agro-ecosystems. Relatively little is known about the positive roles of the application methods for the combination of salicylic acid (SA) and plant nutrients in sustaining wheat production under arid climatic conditions. A two-year field study was undertaken to assess the impact of seven treatments for the integrated application of SA, macronutrients, and micronutrients on the morpho-physiological traits, yield, and irrigation water use efficiency (IWUE) of wheat subjected to full (FL) and limited (LM) irrigation regimes. The results showed that the LM regime caused a significant reduction in different plant growth traits, relative water content, chlorophyll pigments, yield components, and yield, while a significant increase was observed in IWUE. The sole application of SA or co-application with micronutrients through soil did not significantly affect the studied traits under the FL regime, while they achieved some improvement over untreated plants under the LM regime. Based on the different multivariate analyses, the soil and foliar applications for the combinations of SA and micronutrients, as well as a foliar application for the combinations of SA, macronutrients, and micronutrients were identified as an efficient option for mitigating the negative impacts of water deficit stress and enhancing the growth and production of wheat under normal conditions. In conclusion, the results obtained herein indicated that the co-application of SA and macro- and micronutrients is an effective option to greatly enhance and improve the growth and production of wheat crops in water-scarce countries of arid regions, such as Saudi Arabia, while an appropriate application method for this combination was required for positive effects.