Morpho-physiological and biochemical response of wheat to various treatments of silicon nano-particles under drought stress conditions

Stress-Responsive Gene Expression, Metabolic, Physiological, and Agronomic Responses by Consortium Nano-Silica with Trichoderma against Drought Stress in Bread Wheat

The exploitation of drought is a critical worldwide challenge that influences wheat growth and productivity. This study aimed to investigate a synergistic amendment strategy for drought using the single and combined application of plant growth-promoting microorganisms (PGPM) (Trichoderma harzianum) and biogenic silica nanoparticles (SiO2NPs) from rice husk ash (RHA) on Saudi Arabia's Spring wheat Summit cultivar (Triticum aestivum L.) for 102 DAS (days after sowing). The significant improvement was due to the application of 600 ppm SiO2NPs and T. harzianum + 600 ppm SiO2NPs, which enhanced the physiological properties of chlorophyll a, carotenoids, total pigments, osmolytes, and antioxidant contents of drought-stressed wheat plants as adaptive strategies. The results suggest that the expression of the studied genes (TaP5CS1, TaZFP34, TaWRKY1, TaMPK3, TaLEA, and the wheat housekeeping gene TaActin) in wheat remarkably enhanced wheat tolerance to drought stress. We discovered that the genes and metabolites involved significantly contributed to defense responses, making them potential targets for assessing drought tolerance levels. The drought tolerance indices of wheat were revealed by the mean productivity (MP), stress sensitivity index (SSI), yield stability index (YSI), and stress tolerance index (STI). We employed four databases, such as BAR, InterPro, phytozome, and the KEGG pathway, to predict and decipher the putative domains in prior gene sequencing. As a result, we discovered that these genes may be involved in a range of important biological functions in specific tissues at different developmental stages, including response to drought stress, proline accumulation, plant growth and development, and defense response. In conclusion, the sole and/or dual T. harzianum application to the wheat cultivar improved drought tolerance strength. These findings could be insightful data for wheat production in Saudi Arabia under various water regimes.

Foliar-applied silicon and zinc nanoparticles improve plant growth, biochemical attributes, and essential oil profile of fennel (Foeniculum vulgare) under different irrigation regimes

The comparative efficacy of silicon (Si) and zinc (Zn) nanoparticles (NPs) in mitigating drought stress in fennel (Foeniculum vulgare ) remains largely unexplored. This study evaluated the impact of Si NPs and Zn NPs on enhancing plant growth and physiological-biochemical attributes of fennel under varying irrigation regimes. The 2-year study was a split-pot design with irrigation at three irrigation levels (100, 75, and 50% field capacity, FC) and five treatments of foliar application of Si and Zn NPs (control, 1mM Si NP, 2mM Si NP, 1mM Zn NP, 2mM Zn NP). Results showed that drought stress reduced plant performance. Increases in superoxide dismutase (SOD, 131%) and catalase (CAT, 276%) were seen after a 50% FC drought without the use of Si and Zn NPs. Conversely, biological yield (34%), seed yield (44%), chlorophyll a +b (26%), relative water content (RWC, 21%), and essential oil (EO) yield (50%) were all reduced. However, application of Zn and Si, particularly 1mM Si and 2mM Zn, greatly mitigated drought stress via lowering CAT and SOD activity and enhancing plant yield, chlorophyll content, RWC, and EO. The composition of the EO consisted primarily of anethole, followed by limonene, fenchone, and estragole. During drought conditions, monoterpene hydrocarbons increased while oxygenated monoterpenes decreased. The opposite trend was observed for Si and Zn NPs. Our results suggest that applying Zn NPs at 2mM followed by Si NPs at 1mM improved plant resilience and EO yield in fennel plants under water stress.

Abscisic acid improves drought resilience, growth, physio-biochemical and quality attributes in wheat (Triticum aestivum L.) at critical growth stages

Wheat is an important staple crop not only in Pakistan but all over the globe. Although the area dedicated to wheat cultivation expands annually, the quantity of wheat harvested is declining due to various biotic and abiotic factors. Global wheat production and output have suffered as a result of the drought, which is largely driven by a lack of water and environmental factors. Organic fertilizers have been shown to reduce the severity of drought. The current research was conducted in semi-arid climates to mitigate the negative effects of drought on wheat during its critical tillering (DTS), flowering (DFS), and grain filling (DGFS) stages through the application of three different abscisic acid treatments: ABA0 (0 mgL-1) control, ABA1 (100 mgL-1) and ABA2 (200 mgL-1). Wheat growth and yield characteristics were severely harmed by drought stress across all critical development stages, with the DGFS stage being particularly vulnerable and leading to a considerable loss in yield. Plant height was increased by 24.25%, the number of fertile tillers by 25.66%, spike length by 17.24%, the number of spikelets per spike by 16.68%, grain count per spike by 11.98%, thousand-grain weight by 14.34%, grain yield by 26.93% and biological yield by 14.55% when abscisic acid (ABA) was applied instead of the control treatment. Moreover, ABA2 increased the more physiological indices (water use efficiency (36.12%), stomatal conductance (44.23%), chlorophyll a (24.5%), chlorophyll b (29.8%), transpiration rate (23.03%), photosynthetic rate (24.84%), electrolyte leakage (- 38.76%) hydrogen peroxide (- 18.09%) superoxide dismutase (15.3%), catalase (20.8%), peroxidase (- 18.09%), and malondialdehyde (- 13.7%)) of drought-stressed wheat as compared to other treatments. In the case of N, P, and K contents in grain were maximally improved with the application of ABA2. Through the use of principal component analysis, we were able to correlate our results across scales and provide an explanation for the observed effects of ABA on wheat growth and production under arid conditions. Overall, ABA application at a rate of 200 mgL-1 is an effective technique to boost wheat grain output by mitigating the negative effects of drought stress.

Nanopriming boost seed vigor: Deeper insights into the effect mechanism

Nanopriming, an advanced seed priming technology, is highly praised for its environmental friendliness, safety, and effectiveness in promoting sustainable agriculture. Studies have shown that nanopriming can enhance seed germination by stimulating the expression of aquaporins and increasing amylase production. By applying an appropriate concentration of nanoparticles, seeds can generate reactive oxygen species (ROS), enhance their antioxidant capacity, improve their response to oxidative stress, and enhance their tolerance to both biotic and abiotic stresses. This positive impact extends beyond the seed germination and seedling growth stages, persisting throughout the entire life cycle. This review offers a comprehensive overview of recent research progress in seed priming using various nanoparticles, while also addressing current challenges and future opportunities for sustainable agriculture.

Antimicrobial efficacy of nano-particles for crop protection and sustainable agriculture

Plant diseases cause colossal crop loss worldwide and are the major yield constraining component in agriculture. Nanotechnology, which has the possible to revolutionize numerous fields of science, innovation, drug, and agriculture. Nanotechnology can be utilized for combating the plant infectious diseases and nano-materials can be utilized as transporter of dynamic elements of pesticides, host defense etc. to the pathogens. The analysis of diseases, finding of pathogens may turn out to be substantially more precise and fast with the utilization of nanosensors. As worldwide demand for food production raises against an evolving atmosphere, nanotechnology could reasonably alleviate numerous challenges in disease managing by diminishing chemical inputs and advancing quick recognition of pathogens. The major goal of this review is to increase growth and productivity using supplements with nanoparticles. (i.e., metals, metal oxides, and carbon) to treat crop diseases and make agricultural practices more productive and sustainable. Prominently, this improved crop may not only be straight connected to the diminished occurrence of pathogenic microorganisms, yet in might possibly add nutritional benefits of the nanoparticles themselves, particularly for the micronutrients important for generating host resistance.

Effect of CeO2, TiO2 and SiO2 nanoparticles on the growth and quality of model medicinal plant Salvia miltiorrhiza by acting on soil microenvironment

In this study, a six-month pot experiment was conducted to explore the effects of nanoparticles (NPs), including CeO2, TiO2 and SiO2 NPs at 200 and 800 mg/kg, on the growth and quality of model medicinal plant Salvia miltiorrhiza. A control group was implemented without the application of NPs. Results showed that NPs had no significant effect on root biomass. Treatment with 200 mg/kg of SiO2 NPs significantly increased the total tanshinone content by 44.07 %, while 200 mg/kg of CeO2 NPs were conducive to a 22.34 % increase in salvianolic acid B content. Exposure to CeO2 NPs induced a substantial rise in the MDA content in leaves (176.25 % and 329.15 % under low and high concentration exposure, respectively), resulting in pronounced oxidative stress. However, TiO2 and SiO2 NPs did not evoke a robust response from the antioxidant system. Besides, high doses of CeO2 NP-amended soil led to reduced nitrogen, phosphorus and potassium contents. Furthermore, the NP amendment disturbed the carbon and nitrogen metabolism in the plant rhizosphere and reshaped the rhizosphere microbial community structure. The application of CeO2 and TiO2 NPs promoted the accumulation of metabolites with antioxidant functions, such as D-altrose, trehalose, arachidonic acid and ergosterol. NPs displayed a notable suppressive effect on pathogenic fungi (Fusarium and Gibberella) in the rhizosphere, while enriching beneficial taxa with disease resistance, heavy metal antagonism and plant growth promotion ability (Lysobacter, Streptomycetaceae, Bacillaceae and Hannaella). Correlation analysis indicated the involvement of rhizosphere microorganisms in plant adaptation to NP amendments. NPs regulate plant growth and quality by altering soil properties, rhizosphere microbial community structure, and influencing plant and rhizosphere microbe metabolism. These findings were beneficial to deepening the understanding of the mechanism by which NPs affect medicinal plants.

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.

Root-to-shoot signaling positively mediates source-sink relation in late growth stages in diploid and tetraploid wheat

Non-hydraulic root source signaling (nHRS) is a unique positive response to soil drying in the regulation of plant growth and development. However, it is unclear how the nHRS mediates the tradeoff between source and sink at the late growth stages and its adaptive mechanisms in primitive wheat. To address this issue, a root-splitting design was made by inserting solid partition in the middle of the pot culture to induce the occurrence of nHRS using four wheat cultivars (MO1 and MO4, diploid; DM22 and DM31, tetraploid) as materials. Three water treatments were designed as 1) both halves watered (CK), 2) holistic root system watered then droughted (FS), 3) one-half of the root system watered and half droughted (PS). FS and PS were designed to compare the role of the full root system and split root system to induce nHRS. Leaves samples were collected during booting and anthesis to compare the role of nHRS at both growth stages. The data indicated that under PS treatment, ABA concentration was significantly higher than FS and CK, demonstrating the induction of nHRS in split root design and nHRS decreased cytokinin (ZR) levels, particularly in the PS treatment. Soluble sugar and proline accumulation were higher in the anthesis stage as compared to the booting stage. POD activity was higher at anthesis, while CAT was higher at the booting stage. Increased ABA (nHRS) correlated with source-sink relationships and metabolic rate (i.e., leaf) connecting other stress signals. Biomass density showed superior resource acquisition and utilization capabilities in both FS and PS treatment as compared to CK in all plants. Our findings indicate that nHRS-induced alterations in phytohormones and their effect on source-sink relations were allied with the growth stages in primitive wheat.

Assessing Soil Quality, Wheat Crop Yield, and Water Productivity under Condition of Deficit Irrigation

Wheat is one of the most important cereal crops in Egypt and all over the world. Its productivity is adversely affected by drought due to deficient irrigation to provide nutrients required for plant growth. In a field experiment, silicon foliar applications at concentrations of 0, 200, and 400 mg L-1 were performed at different irrigation rates ranging from 1000 to 4000 m3 ha-1 to assess water irrigation productivity and wheat crop yield in a calcareous soil under arid climate conditions. Increased irrigation rates led to a significant increase in soil nutrient dynamics, as well as in the number and weight of grains per spike, leaf area index, grain yield, straw yield, and biological yield, with the exception of the weight of 1000 grains. Spraying with sodium silicate had a significant impact on grain yield and harvest index but did not significantly impact the other traits. Furthermore, the interaction between irrigation and silicate application rates showed significance only for grain yield, the number of spikes/m2, and the harvest index. Applying three times irrigation could produce the highest nutrient retention, wheat yield, and water irrigation productivity. No significance was observed between 3000 m3 ha-1 and 4000 m3 ha-1 irrigation, indicating a saving of 25% of applied irrigation water. It can be concluded that applying irrigation at 3000 m3 ha-1 could be a supplemental irrigation strategy. High wheat grain yield can be achieved under deficit irrigation (3000 m3 ha-1) on the northwestern coast of Egypt with an arid climate by spraying crops with sodium silicate at a rate of 400 mg L-1.

Unlocking the potential of SiO2 and CeO2 nanoparticles for arsenic mitigation in Vigna mungo L. Hepper (Blackgram)

In this study, the interaction effects of NaAsO2 (1 and 5 μM), SiO2 NPs (10 and 100 mg/L) and CeO2 NPs (10 and 100 mg/L) were assessed in Vigna mungo (Blackgram). The treatment of NaAsO2, SiO2, CeO2-NPs and combinations of NPs & As were applied to blackgram plants under hydroponic conditions. After its application, the morpho-physiological, antioxidant activity, and phytochemical study were evaluated. At 10 and 100 mg/L of SiO2 and CeO2-NPs, there was an increase in antioxidative enzymatic activity (p < 0.05) and reactive oxygen species (ROS). However, substantial ROS accumulation was observed at 1 and 5 μM NaAsO2 and 100 mg/L SiO2 NPs (p < 0.05). Additionally, at such concentrations, there is a substantial reduction in photosynthetic pigments, nitrogen fixation, chlorosis, and plant development when compared to controls (p < 0.05). The combination of SiO2 and CeO2 NPs (10 and 100 mg/L) with NaAsO2 decreased superoxide radical and hydrogen peroxide and improved SOD, CAT, APX, GR, and chlorophyll pigments (p < 0.05). Further FTIR results were evaluated for documenting elemental and phytochemical analysis.

Potential of Drought Tolerant Rhizobacteria Amended with Biochar on Growth Promotion in Wheat

Drought stress is the prime obstacle for worldwide agricultural production and necessitates innovative strategies for enhancing crop resilience. This study explores the efficacy of plant growth-promoting rhizobacteria (PGPR) and biochar (BC) as sustainable amendments for mitigating the effects of drought on wheat growth. Multiple experiments were carried out on isolated strains to assess their drought tolerance potential and multiple plant growth-promoting attributes. Experiments in the laboratory and natural environment were conducted to assess the impact of plant growth-promoting rhizobacteria, biochar, and their synergistic application on various growth parameters of wheat. The results revealed that the drought-tolerant PGPR strains (Bacillus subtilis and Bacillus tequilensis), alongside biochar (rice husk), alleviated the phytotoxic impact of drought by increasing the root length from 17.0% to 70.0% and shoot length from 30.0% to 82.0% as compared to un-inoculated stressed controls. The total chlorophyll and carotenoid contents of the plants were substantially increased to 477% and 423%, respectively, when biochar and PGPR were applied synergistically. Significant enhancements in membrane stability index, relative water content, proline, and sugar level were achieved by combining biochar and bacterial strains, resulting in increases of 19.5%, 37.9%, 219%, and 300%, respectively. The yield of wheat in terms of plant height, spike length, number of spikelets per spike, and number of grains per spike was enhanced from 26.7% to 44.6%, 23.5% to 62.7%, 91.5% to 154%, and 137% to 182%, respectively. It was concluded that the biochar-based application of PGPR induced drought tolerance in wheat under water deficit conditions, ultimately improving the production and yield of wheat.

Yield, lodging, and water use efficiency of Tef [Eragrostis tef (zucc) Trotter] in response to carbonized rice husk application under variable moisture condition

Terminal drought and lodging are among the major yield-limiting factors for tef cultivation in the highly weathered soils of the Ethiopian highlands. Therefore, a study was conducted to assess the yield and lodging responses of tef to varying moisture depletion levels (MDL) and the application of carbonized rice husk (CRH). A two-year 4×4 factorial experiment with 20, 35, 55, and 75% MDL and 0, 291, 582, and 873 kg ha-1 of CRH was laid out in a split-plot design, with each treatment replicated four times. The pooled mean ANOVA showed leaf area index (LAI) and lodging index (LI) were not significantly influenced by the main and interaction effects of MDL and CRH (p > 0.05); however, individual year ANOVA showed that both LI and LAI were influenced by the interaction of MDL and CRH (p<0.05) in 2021 and 2022, respectively. The lowest LI (19.7%) was obtained from the application of 873 kg CRH ha-1, followed by 20.6% from 582 kg CRH ha-1 in 2022. A 20.7% LI reduction was recorded in 2022 compared to 2021. Tef plant height and number of tillers per plant were significantly affected by MDL at p<0.05 and p<0.01, respectively, but not by CRH and its interaction with MDL. The effect of MDL was significant on tef HI (p<0.01) but not on traits including grain yield, straw yield, and water use efficiency. In conclusion, the pooled mean analysis result showed that, though there was no significant difference in yield, tef irrigated at 55% MDL provided a maximum HI of 33.8%, which was 6.21% more than the control, and increased the level of lodging resistance with a LI of 31.9%, which was next to 75% MDL with 582 kg ha-1 CRH. The authors suggested that the research should further be verified across locations for wide application.

Review on interactions between nanomaterials and phytohormones: Novel perspectives and opportunities for mitigating environmental challenges

Nanotechnology offers the potential to provide innovative solutions for sustainable crop production as plants are exposed to a combination of climate change factors (CO2, temperature, UV radiation, ozone), abiotic (heavy metals, salinity, drought), and biotic (virus, bacteria, fungi, nematode, and insects) stresses. The application of particular sizes, shapes, and concentration of nanomaterials (NMs) potentially mitigate the negative impacts in plants by modulation of photosynthetic rate, redox homeostasis, hormonal balance, and nutrient assimilation through upregulation of anti-stress metabolites, antioxidant defense pathways, and genes and genes network. The present review inculcates recent advances in uptake, translocation, and accumulation mechanisms of NMs in plants. The critical theme of this review provides detailed insights into different physiological, biochemical, molecular, and stress tolerance mechanism(s) of NMs action and their cross-talk with different phytohormones. The role of NMs as a double-edged sword for climate change factors, abiotic, and biotic stresses for nutrients uptake, hormones synthesis, cytotoxic, and genotoxic effects including chromosomal aberration, and micronuclei synthesis have been extensively studied. Importantly, this review aims to provide an in-depth understanding of the hormesis effect at low and toxicity at higher doses of NMs under different stressors to develop innovative approaches and design smart NMs for sustainable crop production.

Recent advances in nano-fertilizers: synthesis, crop yield impact, and economic analysis

The escalating global demand for food production has predominantly relied on the extensive application of conventional fertilizers (CFs). However, the increased use of CFs has raised concerns regarding environmental risks, including soil and water contamination, especially within cereal-based cropping systems. In response, the agricultural sector has witnessed the emergence of healthier alternatives by utilizing nanotechnology and nano-fertilizers (NFs). These innovative NFs harness the remarkable properties of nanoparticles, ranging in size from 1 to 100 nm, such as nanoclays and zeolites, to enhance nutrient utilization efficiency. Unlike their conventional counterparts, NFs offer many advantages, including variable solubility, consistent and effective performance, controlled release mechanisms, enhanced targeted activity, reduced eco-toxicity, and straightforward and safe delivery and disposal methods. By facilitating rapid and complete plant absorption, NFs effectively conserve nutrients that would otherwise go to waste, mitigating potential environmental harm. Moreover, their superior formulations enable more efficient promotion of sustainable crop growth and production than conventional fertilizers. This review comprehensively examines the global utilization of NFs, emphasizing their immense potential in maintaining environmentally friendly crop output while ensuring agricultural sustainability.

Nano-enabled seed treatment: A new and sustainable approach to engineering climate-resilient crops

Under a changing climate, keeping the food supply steady for an ever-increasing population will require crop plants adapted to environmental fluctuations. Genetic engineering and genome-editing approaches have been used for developing climate-resilient crops. However, genetically modified crops have yet to be widely accepted, especially for small-scale farmers in low-income countries and some societies. Nano-priming (seed exposure to nanoparticles, NPs) has appeared as an alternative to the abovementioned techniques. This technique improves seed germination speed, promotes seedlings' vigor, and enhances plant tolerance to adverse conditions such as drought, salinity, temperature, and flooding, which may occur under extreme weather conditions. Moreover, nano-enabled seed treatment can increase the disease resistance of crops by boosting immunity, which will reduce the use of pesticides. This unsophisticated, farmer-available, cost-effective, and environment-friendly seed treatment approach may help crop plants fight climate change challenges. This review discusses the previous information about nano-enabled seed treatment for enhancing plant tolerance to abiotic stresses and increasing disease resistance. Current knowledge about the mechanisms underlying nanomaterial-seed interactions is discussed. To conclude, the review includes research questions to address before this technique reaches its full potential.

Silicon and titanium nanoparticles modulated drought and chromium toxicity by adjusting physio-biochemical attributes and fatty acid profiles of black cumin (Nigella sativa L.)

Drought and chromium (Cr) stress are the main environmental issues affecting plant performance. Although the positive effects of silicon dioxide (SiO2) and titanium dioxide (TiO2) nanoparticles (NPs) are used as a promising strategy to control abiotic stresses; their synergic effects on controlling drought and Cr toxicity are unknown. This study aimed to investigate the effects of foliar applications of SiO2 (200 mg L-1) and TiO2 (60 mg L-1) NPs on growth, chlorophyll (Chl) content, lipid peroxidation, antioxidant enzyme, and fatty acid profile of black cumin (Nigella sativa L.) under drought (soil moisture at 50% field capacity (FC) and Cr toxicity as K2Cr2O7 at 10 mg L-1. The results showed that drought and Cr stress significantly reduced growth and Chl a + b, but increased malondialdehyde (MDA), electrolyte leakage (EL), and the activity of antioxidant enzymes. The use of NPs particularly SiO2 NPs modulated drought and Cr stress through enhancing Chl content and alleviating MDA, EL, and antioxidant activities. Under drought stress, SiO2 NPs enhanced shoot weight (26%), root weight (25%), seed yield (36%), Chl content (26%), but lowered MDA (22%), EL (14%), catalase (CAT, 32%), and superoxide dismutase (SOD, 33%) activity relative to non-NP application. The main changes in fatty acid profile corresponded to abiotic stresses, where they increased polyunsaturated fatty acids (PUFAs) but decreased monounsaturated fatty acids (MUFAs). Multivariate analysis showed that plant weight, seed yield, Cl content, and oleic acid negatively correlated with MDA, EL, antioxidant enzymes, and linoleic acid. In total, the use of SiO2 is recommended for modulating drought and Cr stress to reach the maximum seed yield of black cumin and a healthy fatty acid profile.

Study of the genetic variability of durum wheat (Triticum durum Desf.) in the face of combined stress: water and heat

The devastating effects and extent of abiotic stress on cereal production continue to increase globally, affecting food security in several countries, including Tunisia. Heat waves and the scarcity of rainfall strongly affect durum wheat yields. The present study aims to screen for tolerance to combined water and heat stresses in durum wheat at the juvenile stage. Three combined treatments were tested, namely: T0 (100% field capacity (FC) at 24 °C), T1 (50% FC at 30 °C), and T2 (25% FC at 35 °C). The screening was carried out based on morphological, physiological, and biochemical criteria. The results showed that the combined stress significantly affected all the measured parameters. The relative water content (RWC) decreased by 37.6% under T1 compared to T0. Quantum yield (Fv/m) and photosynthetic efficiency (Fv/0) decreased under severe combined stress (T2) by 37.15% and 37.22%, respectively. Under T2 stress, LT increased by 63.7%. A significant increase in osmoprotective solutes was also observed, including proline, which increased by 154.6% under T2. Correlation analyses of the combination of water and heat stress confirm that the traits RWC, chlorophyll b content, Fv/m, proline content, Fv/0 and leaf temperature can be used as reliable screening criteria for the two stresses combined. The principal component analysis highlighted that Aouija tolerates the two levels of stresses studied, while the genotypes Karim and Hmira are the most sensitive. The results show that the tolerance of durum wheat to combined water and heat stress involves several adaptation mechanisms proportional to the stress intensity.

Hydrogen-rich water: a key player in boosting wheat (Triticum aestivum L.) seedling growth and drought resilience

In the modern world, wheat, a vital global cereal and the second most consumed, is vulnerable to climate change impacts. These include erratic rainfall and extreme temperatures, endangering global food security. Research on hydrogen-rich water (HRW) has gained momentum in plant and agricultural sciences due to its diverse functions. This study examined the effects of different HRW treatment durations on wheat, revealing that the 4-h treatment had the highest germination rate, enhancing potential, vigor, and germination indexes. This treatment also boosted relative water content, root and shoot weight, and average lengths. Moreover, the 4-h HRW treatment resulted in the highest chlorophyll and soluble protein concentrations in seeds while reducing cell death. The 4-h and 5-h HRW treatments significantly increased H2O2 levels, with the highest NO detected in both root and shoot after 4-h HRW exposure. Additionally, HRW-treated seeds exhibited increased Zn and Fe concentrations, along with antioxidant enzyme activities (CAT, SOD, APX) in roots and shoots. These findings suggest that HRW treatment could enhance wheat seed germination, growth, and nutrient absorption, thereby increasing agricultural productivity. Molecular analysis indicated significant upregulation of the Dreb1 gene with a 4-h HRW treatment. Thus, it shows promise in addressing climate change effects on wheat production. Therefore, HRW treatment could be a hopeful strategy for enhancing wheat plant drought tolerance, requiring further investigation (field experiments) to validate its impact on plant growth and drought stress mitigation.

Integrated transcriptome and metabolome revealed the drought responsive metabolic pathways in Oriental Lily (Lilium L.)

Objective

Lily is an essential ornamental flowering species worldwide. Drought stress is a major constraint affecting the morphology and physiology and lily leaves and flowers. Therefore, understanding the molecular mechanism underlying lily response to drought stress is important.

Method

Transcriptome and metabolome analysis were performed on Oriental Lily subjected to drought stress.

Result

Most transcription factors and metabolites yielded by the conjoint analysis displayed a downregulated expression pattern. Differential genes and metabolites mainly co-enriched in glycolic pathways related to sugars, such as galactose, and sucrose, glycolysis and gluconeogenesis, indicating that drought stress reduced the sugar metabolism level of Oriental Lily. Combined with transcriptome and metabolome data, nine pairs of differentially expressed metabolites and the genes (p < 0.05) were obtained. Interestingly, a gene named TRINITY_DN2608 (encoding a type of alpha-D-glucose) cloned and its overexpression lines in Arabidopsis thaliana was generated. Overexpression of TRINITY_DN2608 gene elevated the susceptibility to drought stress possibly by suppressing the glucose level.

Conclusion

The enrichment of sugar-related pathways advocates the potential role of glucose metabolism in drought stress. Our study provides theoretical information related to the glucose-mediated drought response and would be fruitful in future lily breeding programs.

Acclimation response and management strategies to combat heat stress in wheat for sustainable agriculture: A state-of-the-art review

Unpredicted variability in climate change on the planet is associated with frequent extreme high-temperature events impacting crop yield globally. Wheat is an economically and nutritionally important crop that fulfils global food requirements and each degree rise in temperature results in ∼6% of its yield reduction. Thus, understanding the impact of climate change, especially the terminal heat stress on global wheat production, becomes critically important for policymakers, crop breeders, researchers and scientists to ensure global food security. This review describes how wheat perceives heat stress and induces stress adaptation events by its morpho-physiological, phenological, molecular, and biochemical makeup. Temperature above a threshold level in crop vicinity leads to irreversible injuries, viz. destruction of cellular membranes and enzymes, generation of active oxygen species, redox imbalance, etc. To cope with these changes, wheat activates its heat tolerance mechanisms characterized by hoarding up soluble carbohydrates, signalling molecules, and heat tolerance gene expressions. Being vulnerable to heat stress, increasing wheat production without delay seeks strategies to mitigate the detrimental effects and provoke the methods for its sustainable development. Thus, to ensure the crop's resilience to stress and increasing food demand, this article circumscribes the integrated management approaches to enhance wheat's performance and adaptive capacity besides its alleviating risks of increasing temperature anticipated with climate change. Implementing these integrated strategies in the face of risks from rising temperatures will assist us in producing sustainable wheat with improved yield.

Role of gibberellins, neem leaf extract, and serine in improving wheat growth and grain yield under drought-triggered oxidative stress

The foliar application of gibberellins (GA3), neem leaf extract (NLE) and serine can be proven as effective growth regulating agents to counter drought stress-related deleterious effects. The literature about the collaborative role of these substances in foliar spray application under drought stress is not available to this date. No single report is available in literature on combine foliar application of GA3, NLE, and serine in improving wheat growth and yield under drought-triggered oxidative stress. The objective of this study was to induct tolerance against drought stress in order to sustain maximum growth and yield of wheat varieties (Anaj-2017 and Galaxy-2013) with foliar applications of GA3, NLE, and serine. The current field trial was designed to disclose the protective role of these substances in wheat varieties (Anaj-2017 and Galaxy-2013) under water-deficit stress. Two irrigation levels, i.e., control (normal irrigation) and water stress (water deficit irrigation), and 5 levels of GA3, NLE and serine i.e., control (water spray), GA3 (10.0 ppm), NLE (10.0%), serine (9.5 mM), and mixture (GA3 + NLE + serine) in a 1:1:1 ratio was applied. Application of these substances improved the pigments (Chlorophyll a, b), carotenoids, growth, biomass, and grain yield traits of both wheat varieties under water-deficit stress. Activities of antioxidant enzymes (POD, CAT and SOD), and non-enzymatic antioxidants (proline, total phenolic contents, anthocyanin and free amino acids) were up-regulated under drought stress and with foliar spray treatments. The foliar applications of these substances reduced the drought triggered overproduction of lipid peroxidation (MDA) and H2O2. The study found that Galaxy-2013 variety is more tolerant to drought stress than Anaj-2017, while co-applied treatments (GA3 + NLE + serine) were shown to be the most effective among all applications.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-023-01402-9.

Combination of seed priming and nutrient foliar application improved physiological attributes, grain yield, and biofortification of rainfed wheat

Seed priming and foliar application are two crop management practices that can increase grain yield and quality. The research aimed to assess the influence of seed priming and foliar application on rainfed wheat. Two field experiments with two seed priming rates (control and priming) and five foliar applications [control, urea (4%), silicon (4 mM), FeSO4.7H2O (0.6%), and ZnSO4.7H2O (0.4%)] at the anthesis/Z61 stage were conducted. Seeds were primed for 12 h at 25 ± 2°C, by soaking in an aerating solution [urea (20 g L-1) + FeSO4.7H2O (50 ppm) + ZnSO4.7H2O (50 ppm) + silicon (20 mg L-1)]. Seed weight-to-solution volume ratio was 1:5 (kg L-1). A pot experiment was also conducted to examine the effect of priming on root growth. Overall, combined seed priming and foliar application induced a positive impact on physiological traits and attributes. Maximum chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid concentrations (1.58, 0.669, 2.24, and 0.61 mg g-1 FW), membrane stability index (77.31%), superoxide dismutase and peroxidase activity (0.174 and 0.375 Unit mg-1 protein), 1,000-grain weight (35.30 g), biological yield, grain yield (8,061 and 2,456 kg ha-1), and minimum malondialdehyde concentration (3.91 µg g-1 FW) were observed in seed priming combination with ZnSO4 foliar application. The highest glycine betaine concentration (6.90 mg g-1 DW) and proline (972.8 µg g-1 FW) were recorded with the co-application of seed priming and foliar urea spraying. Foliar application of ZnSO4, FeSO4, and urea drastically enhanced grain Zn (29.17%), Fe (19.51%), and protein content (increased from 11.14% in control to 12.46% in urea foliar application), respectively. Compared to control, seed priming increased root length, root volume, and dry mass root by 8.95%, 4.31%, and 9.64%, respectively. It is concluded that adequate Zn, Fe, silicon, and N supply through seed priming and foliar applications of these compounds at the terminal stage of rainfed wheat alleviates drought stress and improves GY and biofortification.

Novel insights into the mechanism(s) of silicon-induced drought stress tolerance in lentil plants revealed by RNA sequencing analysis

BACKGROUND

Lentil is an essential cool-season food legume that offers several benefits in human nutrition and cropping systems. Drought stress is the major environmental constraint affecting lentil plants' growth and productivity by altering various morphological, physiological, and biochemical traits. Our previous research provided physiological and biochemical evidence showing the role of silicon (Si) in alleviating drought stress in lentil plants, while the molecular mechanisms are still unidentified. Understanding the molecular mechanisms of Si-mediated drought stress tolerance can provide fundamental information to enhance our knowledge of essential gene functions and pathways modulated by Si during drought stress in plants. Thus, the present study compared the transcriptomic characteristics of two lentil genotypes (drought tolerant-ILL6002; drought sensitive-ILL7537) under drought stress and investigated the gene expression in response to Si supplementation using high-throughput RNA sequencing.

RESULTS

This study identified 7164 and 5576 differentially expressed genes (DEGs) from drought-stressed lentil genotypes (ILL 6002 and ILL 7537, respectively), with Si treatment. RNA sequencing results showed that Si supplementation could alter the expression of genes related to photosynthesis, osmoprotection, antioxidant systems and signal transduction in both genotypes under drought stress. Furthermore, these DEGs from both genotypes were found to be associated with the metabolism of carbohydrates, lipids and proteins. The identified DEGs were also linked to cell wall biosynthesis and vasculature development. Results suggested that Si modulated the dynamics of biosynthesis of alkaloids and flavonoids and their metabolism in drought-stressed lentil genotypes. Drought-recovery-related DEGs identified from both genotypes validated the role of Si as a drought stress alleviator. This study identified different possible defense-related responses mediated by Si in response to drought stress in lentil plants including cellular redox homeostasis by reactive oxygen species (ROS), cell wall reinforcement by the deposition of cellulose, lignin, xyloglucan, chitin and xylan, secondary metabolites production, osmotic adjustment and stomatal closure.

CONCLUSION

Overall, the results suggested that a coordinated interplay between various metabolic pathways is required for Si to induce drought tolerance. This study identified potential genes and different defence mechanisms involved in Si-induced drought stress tolerance in lentil plants. Si supplementation altered various metabolic functions like photosynthesis, antioxidant defence system, osmotic balance, hormonal biosynthesis, signalling, amino acid biosynthesis and metabolism of carbohydrates and lipids under drought stress. These novel findings validated the role of Si in drought stress mitigation and have also provided an opportunity to enhance our understanding at the genomic level of Si's role in alleviating drought stress in plants.

Nanosilica enhances morphogenic and chemical parameters of Megathyrsus maximus grass under conditions of phosphorus deficiency and excess stress in different soils

Phosphorus (P) imbalances are a recurring issue in cultivated soils with pastures across diverse regions. In addition to P deficiency, the prevalence of excess P in soil has escalated, resulting in damage to pasture yield. In response to this reality, there is a need for well-considered strategies, such as the application of silicon (Si), a known element for alleviating plant stress. However, the influence of Si on the morphogenetic and chemical attributes of forage grasses grown in various soils remains uncertain. Consequently, this study aimed to assess the impact of P deficiency and excess on morphogenetic and chemical parameters, as well as digestibility, in Zuri guinea grass cultivated in Oxisol and Entisol soils. It also sought to determine whether fertigation with nanosilica could mitigate the detrimental effects of these nutritional stresses. Results revealed that P deficiency led to a reduction in tiller numbers and grass protein content, along with an increase in lignin content. Conversely, P excess resulted in higher proportions of dead material and lignin, a reduced mass leaf: stem ratio in plants, and a decrease in dry matter (DM) yield. Fertigation with Si improved tillering and protein content in deficient plants. In the case of P excess, Si reduced tiller mortality and lignin content, increased the mass leaf:stem ratio, and enhanced DM yield. This approach also increased yields in plants with sufficient P levels without affecting grass digestibility. Thus, Si utilization holds promise for enhancing the growth and chemical characteristics of forage grasses under P stress and optimizing yield in well-nourished, adapted plants, promoting more sustainable pasture yields.

Nanoparticle-mediated amelioration of drought stress in plants: a systematic review

Drought stress remains one of the most detrimental environmental constraints that hampers plant growth and development resulting in reduced yield and leading to economic losses. Studies have highlighted the beneficial role of carbon-based nanomaterials (NMs) such as multiwalled carbon nanotubes (MWNTs), single-walled carbon nanotubes (SWNTs), graphene, fullerene, and metal-based nanoparticles (NPs) (Ag, Au, Cu, Fe2O3, TiO2, and ZnO) in plants under unfavorable conditions such as drought. NPs help plants cope with drought by improving plant growth indices and enhancing biomass. It improves water and nutrient uptake and utilization. It helps retain water by altering the cell walls and regulating stomatal closure. The photosynthetic parameters in NP-treated plants reportedly improved with the increase in pigment content and rate of photosynthesis. Due to NP exposure, the activation of enzymatic and nonenzymatic antioxidants has reportedly improved. These antioxidants play a significant role in the defense system against stress. Studies have reported the accumulation of osmolytes and secondary metabolites. Osmolytes scavenge reactive oxygen species, which can cause oxidative stress in plants. Secondary metabolites are involved in the water retention process, thus improving plant coping strategies with stress. The deleterious effects of drought stress are alleviated by reducing malondialdehyde resulting from lipid peroxidation. Reactive oxygen species accumulation is also controlled with NP treatment. Furthermore, NPs have been reported to regulate the expression of drought-responsive genes and the biosynthesis of phytohormones such as abscisic acid, auxin, gibberellin, and cytokinin, which help plants defend against drought stress. This study reviewed 72 journal articles from 192 Google Scholar, ScienceDirect, and PubMed papers. In this review, we have discussed the impact of NP treatment on morphological, physio-biochemical, and molecular responses in monocot and dicot plants under drought conditions with an emphasis on NP uptake, transportation, and localization.

Effect of drought acclimation on antioxidant system and polyphenolic content of Foxtail Millet (Setaria italica L.)

The impact of climate change-induced drought stress on global food security and environmental sustainability is a serious concern. While previous research has highlighted the potential benefits of drought hardening in improving plants' ability to withstand drought, the exact underlying physiological mechanisms in millet plants (Setaria italica L.) have not been explored. This study aimed to investigate the impact of drought hardening on antioxidant defense and polyphenol accumulation in different millet genotypes ('PI 689680' and 'PI 662292') subjected to different treatments: control (unstressed), drought acclimation (two stress episodes with recovery), and non-acclimation (single stress episode with no recovery). The results showed that drought stress led to higher levels of polyphenols and oxidative damage, as indicated by increased phenolic, flavonoid, and anthocyanin levels. Non-acclimated (NA) plants experienced more severe oxidative damage and inhibition of enzymes associated with the ascorbate glutathione cycle compared to drought-acclimated plants. NA plants also exhibited a significant reduction in photosynthesis and tissue water content. The expression of genes related to antioxidants and polyphenol synthesis was more pronounced in non-acclimated plants. The study demonstrated that drought hardening not only prepared plants for subsequent drought stress but also mitigated damage caused by oxidative stress in plant physiology. Drought-acclimated (DA) plants displayed improved drought tolerance, as evidenced by better growth, photosynthesis, antioxidant defense, polyphenol accumulation, and gene expression related to antioxidants and polyphenol synthesis. In conclusion, the research advocates for the use of drought hardening as an effective strategy to alleviate the negative impacts of drought-induced metabolic disturbances in millet.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-023-01366-w.

Nutrient management: as a panacea to improve the caryopsis quality and yield potential of durum wheat (Triticum turgidum L.) under the changing climatic conditions

The increasing human population and the changing climate, which have given rise to frequent drought spells, pose a serious threat to global food security, while identification of high-yielding drought-tolerant genotypes coupled with nutrient management remains a proficient approach to cope with these challenges. An increase in seasonal temperature, recurring drought stress, and elevated atmospheric CO2 are alarmingly affecting durum wheat production, productivity, grain quality, and the human systems it supports. An increase in atmospheric carbon dioxide can improve wheat grain yield in a certain amount, but the right amount of nutrients, water, and other required conditions should be met to realize this benefit. Nutrients including nitrogen, silicon, and sulfur supply could alleviate the adverse effects of abiotic stress by enhancing antioxidant defense and improving nitrogen assimilation, although the effects on plant tolerance to drought stress varied with nitrogen ionic forms. The application of sewage sludge to durum wheat also positively impacts its drought stress tolerance by triggering high accumulation of osmoregulators, improving water retention capacity in the soil, and promoting root growth. These beneficial effect of nutrients contribute to durum wheat ability to withstand and recover from abiotic stress conditions, ultimately enhance its productivity and resilience. While these nutrients can provide benefits when applied in appropriate amounts, their excessive use can lead to adverse environmental consequences. Advanced technologies such as precision nutrient management, unmanned aerial vehicle-based spraying, and anaerobic digestion play significant roles in reducing the negative effects associated with nutrients like sewage sludge, zinc, nanoparticles and silicon fertilizers. Hence, nutrient management practices offer significant potential to enhance the caryopsis quality and yield potential of durum wheat. Through implementing tailored nutrient management strategies, farmers, breeders, and agronomists can contribute to sustainable durum wheat production, ensuring food security and maintaining the economic viability of the crop under the changing climatic conditions.

Silicon nanoparticles: Comprehensive review on biogenic synthesis and applications in agriculture

Recent advancements in nanotechnology have opened new advances in agriculture. Among other nanoparticles, silicon nanoparticles (SiNPs), due to their unique physiological characteristics and structural properties, offer a significant advantage as nanofertilizers, nanopesticides, nanozeolite and targeted delivery systems in agriculture. Silicon nanoparticles are well known to improve plant growth under normal and stressful environments. Nanosilicon has been reported to enhance plant stress tolerance against various environmental stress and is considered a non-toxic and proficient alternative to control plant diseases. However, a few studies depicted the phytotoxic effects of SiNPs on specific plants. Therefore, there is a need for comprehensive research, mainly on the interaction mechanism between NPs and host plants to unravel the hidden facts about silicon nanoparticles in agriculture. The present review illustrates the potential role of silicon nanoparticles in improving plant resistance to combat different environmental (abiotic and biotic) stresses and the underlying mechanisms involved. Furthermore, our review focuses on providing the overview of various methods exploited in the biogenic synthesis of silicon nanoparticles. However, certain limitations exist in synthesizing the well-characterized SiNPs on a laboratory scale. To bridge this gap, in the last section of the review, we discussed the possible use of the machine learning approach in future as an effective, less labour-intensive and time-consuming method for silicon nanoparticle synthesis. The existing research gaps from our perspective and future research directions for utilizing SiNPs in sustainable agriculture development have also been highlighted.

The use of silicon and mycorrhizal fungi to mitigate changes in licorice leaf micromorphology, chlorophyll fluorescence, and rutin content under water-deficit conditions

In this study, the effects of water-deficit conditions, silicon (Si) fertilizer (300 ppm), and arbuscular mycorrhizal (AM) inoculation by Claroiedoglomus etunicatum were evaluated on several features of licorice (Glycyrrhiza glabra L.). The measurable features were photosynthetic parameters, rutin content in aerial parts, and leaf micromorphology. Drought was administered at five levels determined by the percentage of field capacity (FC), i.e. 100, 80, 60, 40, and 20% of FC. Leaf extracts were utilized for measuring rutin content (via HPLC), and photosynthetic pigments; measurement of stomatal density, and trichome analysis were performed by scanning electron microscopy (SEM). Under severe drought stress, leaf area decreased by 50.84%, compared to well-irrigated plants. A significant decrease in leaf numbers (32.52%) was observed because of deficit irrigation. AM and Si improved chlorophyll fluorescence, which corresponded to the maximum efficiency of photosystem II. Rutin content decreased significantly under deficit irrigation. Also, the integration of AM and Si treatments positively affected rutin quantity under various irrigation regimes. Under moderate stress (60% FC), using AM and/or Si treatments reduced the stomatal length by 61.22 and 52.98%, respectively. Interestingly, a significant reduction in stomatal density towards control was observed as a result of the integrated treatments of Si and AM (58.28% at W₂₀ and 59.82% at W₁₀₀), which helped plants reduce water loss when facing drought stress. Principal component analysis (PCA) showed that photosynthetic pigments, chlorophyll fluorescence, and rutin changed quantitatively under moderate drought stress, while more variations were observed in leaf epidermal micromorphology under severe drought stress. These findings revealed that Si and AM, by exogenous application, synergistically mitigated the effects of drought stress on licorice.