Nano-iron oxide accelerates growth, yield, and quality of Glycine max seed in water deficits

Manure-biochar compost mitigates the soil salinity stress in tomato plants by modulating the osmoregulatory mechanism, photosynthetic pigments, and ionic homeostasis

One of the main abiotic stresses that affect plant development and lower agricultural productivity globally is salt in the soil. Organic amendments, such as compost and biochar can mitigate the opposing effects of soil salinity (SS) stress. The purpose of this experiment was to look at how tomato growth and yield on salty soil were affected by mineral fertilization and manure-biochar compost (MBC). Furthermore, the study looked at how biochar (organic amendments) work to help tomato plants that are stressed by salt and also a mechanism by which biochar addresses the salt stress on tomato plants. Tomato yield and vegetative growth were negatively impacted by untreated saline soil, indicating that tomatoes are salt-sensitive. MBC with mineral fertilization increased vegetative growth, biomass yield, fruit yield, chlorophyll, and nutrient contents, Na/K ratio of salt-stressed tomato plants signifies the ameliorating effects on tomato plant growth and yield, under salt stress. Furthermore, the application of MBC with mineral fertilizer decreased H2O2, but increased leaf relative water content (RWC), leaf proline, total soluble sugar, and ascorbic acid content and improved leaf membrane damage, in comparison with untreated plants, in response to salt stress. Among the composting substances, T7 [poultry manure-biochar composting (PBC) (1:2) @ 3 t/ha + soil-based test fertilizer (SBTF)] dose exhibited better-improving effects on salt stress and had maintained an order of T7 > T9 > T8 > T6 in total biomass and fruit yield of tomato. These results suggested that MBC might mitigate the antagonistic effects of salt stress on plant growth and yield of tomatoes by improving osmotic adjustment, antioxidant capacity, nutrient accumulation, protecting photosynthetic pigments, and reducing ROS production and leaf damage in tomato plant leaves.

Iron nanoparticles in combination with other conventional Fe sources remediate mercury toxicity-affected plants and soils by nutrient accumulation in bamboo species

The issue of mercury (Hg) toxicity has recently been identified as a significant environmental concern, with the potential to impede plant growth in forested and agricultural areas. Conversely, recent reports have indicated that Fe, may play a role in alleviating HM toxicity in plants. Therefore, this study's objective is to examine the potential of iron nanoparticles (Fe NPs) and various sources of Fe, particularly iron sulfate (Fe SO4 or Fe S) and iron-ethylene diamine tetra acetic acid (Fe - EDTA or Fe C), either individually or in combination, to mitigate the toxic effects of Hg on Pleioblastus pygmaeus. Involved mechanisms in the reduction of Hg toxicity in one-year bamboo species by Fe NPs, and by various Fe sources were introduced by a controlled greenhouse experiment. While 80 mg/L Hg significantly reduced plant growth and biomass (shoot dry weight (36%), root dry weight (31%), and shoot length (31%) and plant tolerance (34%) in comparison with control treatments, 60 mg/L Fe NPs and conventional sources of Fe increased proline accumulation (32%), antioxidant metabolism (21%), polyamines (114%), photosynthetic pigments (59%), as well as root dry weight (25%), and shoot dry weight (22%), and shoot length (22%). Fe NPs, Fe S, and Fe C in plant systems substantially enhanced tolerance to Hg toxicity (23%). This improvement was attributed to increased leaf-relative water content (39%), enhanced nutrient availability (50%), improved antioxidant capacity (34%), and reduced Hg translocation (6%) and accumulation (31%) in plant organs. Applying Fe NPs alone or in conjunction with a mixture of Fe C and Fe S can most efficiently improve bamboo plants' tolerance to Hg toxicity. The highest efficiency in increasing biochemical and physiological indexes under Hg, was related to the treatments of Fe NPs as well as Fe NPs + FeS + FeC. Thus, Fe NPs and other Fe sources might be effective options to remove toxicity from plants and soil. The future perspective may help establish mechanisms to regulate environmental toxicity and human health progressions.

Unveiling key mechanisms: Transcriptomic meta-analysis of diverse nanomaterial applications addressing biotic and abiotic stresses in Arabidopsis Thaliana

The potential applications of nanomaterials in agriculture for alleviating diverse biotic and abiotic stresses have garnered significant attention. The reported mechanisms encompass promoting plant growth and development, alleviating oxidative stress, inducing defense responses, modulating plant-microbe interactions, and more. However, individual studies may not fully uncover the common pathways or distinguish the effects of different nanostructures. We examined Arabidopsis thaliana transcriptomes exposed to biotic, abiotic, and metal or carbon-based nanomaterials, utilizing 24 microarray chipsets and 17 RNA-seq sets. The results showed that: 1) from the perspective of different nanostructures, all metal nanomaterials relieved biotic/abiotic stresses via boosting metal homeostasis, particularly zinc and iron. Carbon nanomaterials induce hormone-related immune responses in the presence of both biotic and abiotic stressors. 2) Considering the distinct features of various nanostructures, metal nanomaterials displayed unique characteristics in seed priming for combating abiotic stresses. In contrast, carbon nanomaterials exhibited attractive features in alleviating water deprivation and acting as signaling amplifiers during biotic stress. 3) For shared pathway analysis, response to hypoxia emerges as the predominant and widely shared regulatory mechanism governing diverse stress responses, including those induced by nanomaterials. By deciphering shared and specific pathways and responses, this research opens new avenues for precision nano-agriculture, offering innovative strategies to optimize plant resilience, improve stress management, and advance sustainable crop production practices.

Nutritional and bioactive properties and antioxidant potential of Amaranthus tricolor, A. lividus, A viridis, and A. spinosus leafy vegetables

Climate change results in continuous warming of the planet, threatening sustainable crop production around the world. Amaranth is an abiotic stress-tolerant, climate-resilient, C4 leafy orphan vegetable that has grown rapidly with great divergence and potential usage. The C4 photosynthesis allows amaranth to be grown as a sustainable future food crop across the world. Most amaranth species grow as weeds in many parts of the world, however, a few amaranth species can be also found in cultivated form. Weed species can be used as a folk medicine to relieve pain or reduce fever thanks to their antipyretic and analgesic properties. In this study, nutritional value, bioactive pigments, bioactive compounds content, and radical scavenging potential (RSP) of four weedy and cultivated (WC) amaranth species were evaluated. The highest dry matter, carbohydrate content, ash, content of iron, copper, sodium, boron, molybdenum, zinc, β-carotene and carotenoids, vitamin C, total polyphenols (TP), RSP (DPPH), and RSP (ABTS+) was determined in Amaranthus viridis (AV). On the other hand, A. spinosus (AS) was found to have the highest content of protein, fat, dietary fiber, manganese, molybdenum, and total flavonoids (TF). In A. tricolor (AT) species the highest total chlorophyll, chlorophyll a and b, betaxanthin, betacyanin, and betalain content was determined. A. lividus (AL) was evaluated as the highest source of energy. AV and AT accessions are underutilized but promising vegetables due to their bioactive phytochemicals and antioxidants.

Impact of airborne iron oxide nanoparticles on Tillandsia usneoides as a model plant to assess pollution in heavy traffic areas

Due to the increasing evidence of widespread sub-micron pollutants in the atmosphere, the impact of airborne nanoparticles is a subject of great relevance. In particular, the smallest particles are considered the most active and dangerous, having a higher surface/volume ratio. Here we tested the effect of iron oxide (Fe3O4) nanoparticles (IONPs) with different mean diameter and size distribution on the model plant Tillandsia usneoides. Strands were placed in home-built closed boxes and exposed to levels of airborne IONPs reported for the roadside air, i.e. in the order of 107 - 108 items m-2. Plant growth and other morpho-physiological parameters were monitored for two weeks, showing that exposure to IONPs significantly reduced the length increment of the treated strands with respect to controls. A dose-dependence of this impairing effect was found only for particles with mean size of a few tens of nanometers. These were also proved to be the most toxic at the highest concentration tested. The IONP-induced hamper in growth was correlated with altered concentration of macro- and micronutrients in the plant, while no significant variation in photosynthetic activity was detected in treated samples. Microscopy investigation showed that IONPs could adhere to the plant surface and were preferentially located on the trichome wings. Our results report, for the first time, evidence of the negative effects of airborne IONP pollution on plant health, thus raising concerns about related environmental risks. Future research should be devoted to other plant species and pollutants to assess the impact of airborne pollution on plants and devise suitable attenuation practices.

Changes in Photosystem II Complex and Physiological Activities in Pea and Maize Plants in Response to Salt Stress

Salt stress significantly impacts the functions of the photosynthetic apparatus, with varying degrees of damage to its components. Photosystem II (PSII) is more sensitive to environmental stresses, including salinity, than photosystem I (PSI). This study investigated the effects of different salinity levels (0 to 200 mM NaCl) on the PSII complex in isolated thylakoid membranes from hydroponically grown pea (Pisum sativum L.) and maize (Zea mays L.) plants treated with NaCl for 5 days. The data revealed that salt stress inhibits the photochemical activity of PSII (H2O → BQ), affecting the energy transfer between the pigment-protein complexes of PSII (as indicated by the fluorescence emission ratio F695/F685), QA reoxidation, and the function of the oxygen-evolving complex (OEC). These processes were more significantly affected in pea than in maize under salinity. Analysis of the oxygen evolution curves after flashes and continuous illumination showed a stronger influence on the PSIIα than PSIIβ centers. The inhibition of oxygen evolution was associated with an increase in misses (α), double hits (β), and blocked centers (SB) and a decrease in the rate constant of turnover of PSII reaction centers (KD). Salinity had different effects on the two pathways of QA reoxidation in maize and pea. In maize, the electron flow from QA- to plastoquinone was dominant after treatment with higher NaCl concentrations (150 mM and 200 mM), while in pea, the electron recombination on QAQB- with oxidized S2 (or S3) of the OEC was more pronounced. Analysis of the 77 K fluorescence emission spectra revealed changes in the ratio of the light-harvesting complex of PSII (LHCII) monomers and trimers to LHCII aggregates after salt treatment. There was also a decrease in pigment composition and an increase in oxidative stress markers, membrane injury index, antioxidant activity (FRAP assay), and antiradical activity (DPPH assay). These effects were more pronounced in pea than in maize after treatment with higher NaCl concentrations (150 mM-200 mM). This study provides insights into how salinity influences the processes in the donor and acceptor sides of PSII in plants with different salt sensitivity.

Zinc oxide and ferric oxide nanoparticles combination increase plant growth, yield, and quality of soybean under semiarid region

Zinc (Zn) and iron (Fe) malnutrition are global health challenges that need immediate attention. Hence, to address these issues, a two-pronged approach involving the development and application of novel Zn and Fe products for crop fertilization may be a potential solution. Therefore, zinc oxide (ZnO) (∼13.2 nm) and ferric oxide (Fe2O3) (∼15 nm) nanoparticles (NPs) were synthesized and characterized. Seven nutrients treatments viz, control, ZnO- NPs (25 mg kg-1), Fe2O3-NPs (25 mg kg-1), ZnO + Fe2O3-NPs (25 mg kg-1each), ZnSO4 (55.8 mg kg-1), FeSO4 (60.4 mg kg-1) and ZnSO4+ FeSO4 (55.8 and 60.4 mg kg-1) were arranged in five-time replicated Completely Randomized Design model to test the effectiveness of ZnO and Fe2O3 NPs in two soybean cultivars over conventional zinc sulfate (ZnSO4) and ferrous sulfate (FeSO4) fertilizers. The results indicated that the photosynthetic rate (Pn) and chlorophyll content increased (33.9-86.2%) significantly at the flowering stage with ZnO and Fe2O3 NPs applications, compared to their conventional counterparts. Likewise, the combined application of ZnO and Fe2O3 NPs reduced H2O2 production by 17-19% and increased the superoxide dismutase (SOD) and catalase (CAT) activities by 15-17% and 9.6-11.4% over the combined use of ZnSO4 and FeSO4, respectively. The normalized difference vegetation index (NDVI) showed an increase of 6.9-44.2% under ZnO and Fe2O3 NPs, as well as ZnSO4 and FeSO4. Furthermore, the combined application of NPs enhanced soybean seed yield by 4.6-18.3% compared to conventional Zn and Fe fertilizers. Concerning seed Zn and Fe density, conjoint application of ZnO and Fe2O3 NPs increases Zn by 1.8-2.2-fold and Fe by 19.22-22.58% over the combined application of Zn SO4 and FeSO4, respectively. While the application of NPs significantly decreased seed phytic acid concentrations by 7.3-59.9% compared to the control. These findings suggest that the combined application of ZnO and Fe2O3 NPs effectively enhances soybean productivity, seed nutrient density, and overall produce quality. Therefore, the combined application of ZnO and Fe2O3 -NPs in soybean can be a potential approach for sustainable soybean production and to reduce/arrest Zn and Fe malnutrition in a growing population.

The effects of iron-based nanomaterials (Fe NMs) on plants under stressful environments: Machine learning-assisted meta-analysis

Mitigating the adverse effects of stressful environments on crops and promoting plant recovery in contaminated sites are critical to agricultural development and environmental remediation. Iron-based nanomaterials (Fe NMs) can be used as environmentally friendly nano-fertilizer and as a means of ecological remediation. A meta-analysis was conducted on 58 independent studies from around the world to evaluate the effects of Fe NMs on plant development and antioxidant defense systems in stressful environments. The application of Fe NMs significantly enhanced plant biomass (mean = 25%, CI = 20%-30%), while promoting antioxidant enzyme activity (mean = 14%, CI = 10%-18%) and increasing antioxidant metabolite content (mean = 10%, CI = 6%-14%), reducing plant oxidative stress (mean = -15%, CI = -20%∼-10%), and alleviating the toxic effects of stressful environments. The observed response was dependent on a number of factors, which were ranked in terms of a Random Forest Importance Analysis. Plant species was the most significant factor, followed by Fe NM particle size, duration of application, dose level, and Fe NM type. The meta-analysis has demonstrated the potential of Fe NMs in achieving sustainable agriculture and the future development of phytoremediation.

Uptake and bioaccumulation of iron oxide nanoparticles (Fe3O4) in barley (Hordeum vulgare L.): effect of particle-size

Root-to-shoot translocation of nanoparticles (NPs) is a matter of interest due to their possible unprecedented effects on biota. Properties of NPs, such as structure, surface charge or coating, and size, determine their uptake by cells. This study investigates the size effect of iron oxide (Fe3O4) NPs on plant uptake, translocation, and physiology. For this purpose, Fe3O4 NPs having about 10 and 100 nm in average sizes (namely NP10 and NP100) were hydroponically subjected to barley (Hordeum vulgare L.) in different doses (50, 100, and 200 mg/L) at germination (5 days) and seedling (3 weeks) stages. Results revealed that particle size does not significantly influence the seedlings' growth but improves germination. The iron content in root and leaf tissues gradually increased with increasing NP10 and NP100 concentrations, revealing their root-to-shoot translocation. This result was confirmed by vibrating sample magnetometry analysis, where the magnetic signals increased with increasing NP doses. The translocation of NPs enhanced chlorophyll and carotenoid contents, suggesting their contribution to plant pigmentation. On the other hand, catalase activity and H2O2 production were higher in NP10-treated roots compared to NP100-treated ones. Besides, confocal microscopy revealed that NP10 leads to cell membrane damages. These findings showed that Fe3O4 NPs were efficiently taken up by the roots and transported to the leaves regardless of the size factor. However, small-sized Fe3O4 NPs may be more reactive due to their size properties and may cause cell stress and membrane damage. This study may help us better understand the size effect of NPs in nanoparticle-plant interaction.

Gibberellin-Producing Bacteria Isolated from Coastal Soil Enhance Seed Germination of Mallow and Broccoli Plants under Saline Conditions

Salinity hinders plant growth, posing a substantial challenge to sustainable agricultural yield maintenance. The application of plant growth-promoting rhizobacteria (PGPR) offers an emerging strategy to mitigate the detrimental effects of high salinity levels. This study aimed to isolate and identify gibberellin-producing bacteria and their impact on the seed germination of Malva verticillata (mallow) and Brassica oleracea var. italica (broccoli) under salt stress. In this study, seven bacterial isolates (KW01, KW02, KW03, KW04, KW05, KW06, and KW07) were used to assess their capacity for producing various growth-promoting traits and their tolerance to varying amounts of salinity (100 mM and 150 Mm NaCl). The findings revealed that KW05 and KW07 isolates outperformed other isolates in synthesizing indole-3-acetic acid, siderophores, and exopolysaccharides and in solubilizing phosphates. These isolates also enhanced phosphatase activity and antioxidant levels, including superoxide dismutase and catalase. Both KW05 and KW07 isolate highlight the growth-promoting effects of gibberellin by enhancing of growth parameters of Waito-C rice. Further, gas chromatography-mass spectrometry validation confirmed the ability of KW05 and KW07 to produce gibberellins (GAs), including GA1, GA3, GA4, and GA7. Seed germination metrics were enhanced due to the inoculation of KW05 and KW07. Moreover, inoculation with KW05 increased the fresh weight (FW) (7.82%) and total length (38.61%) of mallow under salt stress. Inoculation with KW07 increased the FW (32.04%) and shoot length of mallow under salt stress. A single inoculation of these two isolates increased broccoli plants' FW and shoot length under salt stress. Gibberellin-producing bacteria helps in plant growth promotion by improving salt tolerance by stimulating root elongation and facilitating enhanced absorption of water and nutrient uptake in salty environments. Based on these findings, they can play a role in boosting agricultural yield in salt-affected areas, which would help to ensure the long-term viability of agriculture in coastal regions.

Efficacy of priming wheat (Triticum aestivum) seeds with a benzothiazine derivative to improve drought stress tolerance

We evaluated the effects of different concentrations (0.05 and 0.15mM) of a benzothiazine (BTh) derivative on wheat (Triticum aestivum L.) in normal (100% field water capacity, FWC) and drought (60% FWC) conditions. Various morphological and physiological characteristics, and the uptake of osmo-protectants and nutrients were measured under the two FWC conditions. Results show that the drought conditions significantly reduced plant growth, affected plant composition, reduced the concentrations of photosynthetic pigments and affected gaseous exchange attributes, stomatal behaviour, and uptake fluxes of essential nutrients, while increasing the contents of different osmo-protectants and enzymatic and non-enzymatic antioxidants to decrease the production of reactive oxygen species (ROS) within the cells/tissues. However, seed priming with BTh reduced water stress conditions by increasing plant growth and biomass, photosynthetic pigments, stomatal behaviour, different gaseous exchange attributes, and uptake fluxes of essential nutrients compared with unprimed plants. In addition, the plant has a strong antioxidant defense system, which further increased its activities under BTh derivative treatments, to scavenge ROS production and maintain cell turgor under water stress conditions. In conclusion, drought stress-induced oxidative stress and altered the growth of T. aestivum , whereas seed priming increased plant growth and antioxidant production by improving the plant tolerance to drought. We suggest that seed priming with a BTh derivative as an effective priming technique in T. aestivum for reducing drought stress tends to benefit a grower in terms of better growth to fulfil the market demand for food cereals.

Exploring the recuperative potential of brassinosteroids and nano-biochar on growth, physiology, and yield of wheat under drought stress

Drought stress as a result of rapidly changing climatic conditions has a direct negative impact on crop production especially wheat which is the 2nd staple food crop. To fulfill the nutritional demand under rapidly declining water resources, there is a dire need to adopt a precise, and efficient approach in the form of different amendments. In this regard, the present study investigated the impact of nano-biochar (NBC) and brassinosteroids (BR) in enhancing the growth and productivity of wheat under different drought stress conditions. The field study comprised different combinations of amendments (control, NBC, BR, and NBC + BR) under three irrigation levels (D0, D1 and D2). Among different treatments, the synergistic approach (NBC + BR) resulted in the maximum increase in different growth and yield parameters under normal as well as drought stress conditions. With synergistic approach (NBC + BR), the maximum plant height (71.7 cm), spike length (17.1), number of fertile tillers m-2 (410), no. of spikelets spike-1 (19.1), no. of grains spike-1 (37.9), 1000 grain weight (37 g), grain yield (4079 kg ha-1), biological yield (10,502 kg ha-1), harvest index (43.5). In the case of physiological parameters such as leaf area index, relative water contents, chlorophyll contents, and stomatal conductance were maximally improved with the combined application of NBC and BR. The same treatment caused an increase of 54, 10, and 7% in N, P, and K contents in grains, respectively compared to the control treatment. Similarly, the antioxidant response was enhanced in wheat plants under drought stress with the combined application of NBC and BR. In conclusion, the combined application of NBC and BR caused a significant increase in the growth, physiological and yield attributes of wheat under drought stress.

Biochar and Seed Priming Technique with Gallic Acid: An Approach toward Improving Morpho-Anatomical and Physiological Features of Solanum melongena L. under Induced NaCl and Boron Stresses

Dynamic shifts in climatic patterns increase soil salinity and boron levels, which are the major abiotic factors that affect plant growth and secondary metabolism. The present study assessed the role of growth regulators, including biochar (5 g kg-1) and gallic acid (GA, 2 mM), in altering leaf morpho-anatomical and physiological responses of Solanum melongena L. exposed to boron (25 mg kg-1) and salinity stresses (150 mM NaCl). These growth regulators enhanced leaf fresh weight (LFW) (70%), leaf dry weight (LDW) (20%), leaf area (LA), leaf area index (LAI) (85%), leaf moisture content (LMC) (98%), and relative water content (RWC) (115%) under salinity and boron stresses. Physiological attributes were analyzed to determine the stress levels and antioxidant protection. Photosynthetic pigments were negatively affected by salinity and boron stresses along with a nonsignificant reduction in trehalose, GA, osmoprotectant, and catalase (CAT) and ascorbate peroxidase (APX) activity. These parameters were improved by biochar application to soil and presoaking seeds in GA (p < 0.05) in both varieties of S. melongena L. Scanning electron microscopy (SEM) and light microscopy revealed that application of biochar and GA improved the stomatal regulation, trichome density, epidermal vigor, stomata size (SS) (13 381 μm), stomata index (SI) (354 mm2), upper epidermis thickness (UET) (123 μm), lower epidermis thickness (LET) (153 μm), cuticle thickness (CT) (11.4 μm), trichome density (TD) (23 per mm2), vein islet number (VIN) (14 per mm2), vein termination number (VTN) (19 per mm2), midrib thickness (MT) (5546 μm), and TD (27.4 mm2) under salinity and boron stresses. These results indicate that the use of inexpensive and easily available biochar and seed priming with GA can improve morpho-anatomical and physiological responses of S. melongena L. under oxidative stress conditions.

Effects of Poultry Manure on the Growth, Physiology, Yield, and Yield-Related Traits of Maize Varieties

Industries play a significant role in the improvement of lifestyle and in the development of a country. However, the byproducts from these industries are a source of environmental pollution. The proper use of the byproducts of these industries can help to cope with environmental pollution. Some byproducts have high nutritional content and are good for crop plants. The purpose of this research was to investigate the effect of different rates of poultry manure on the soil chemical properties, growth, and yield of maize. A pot experiment was conducted in the botanical garden of the Department of Botany, University of Sargodha, Pakistan to investigate the effect of various treatments of poultry manure (0, 25, 50, 75, and 100 g/pot) on the morphological, physiological, and yield attributes of two maize varieties, Pearl and MMRI. Treatment T₁ was a mixture of soil and 75 g/pot poultry manure, T₂ was a mixture of soil and 50 g/pot poultry manure, T₃ was a mixture of soil and 25 g/pot poultry manure, and T₄ was 100 g/pot poultry manure. Soil without any industrial byproduct (100% soil only) was used as the control (T₀). The results revealed that the use of poultry manure enhanced the physical properties of the soil. Available P and soil organic matter were improved in soil amended with poultry manure. It is evident from the results that the vegetative growth of both maize varieties was significantly enhanced by growing in soil amended with poultry manure as compared to their respective control. Similar responses were also recorded for the physiological attributes of leaf area, photosynthetic rate, transpiration rate, stomatal conductance, and water use efficiency of both varieties. Yield and yield-contributing traits of both maize varieties were significantly improved by growing plants in soil amended with 50 and 75 g/pot of poultry manure. It is also inferred that the use of 50 g/pot poultry manure in soil amendment is an eco-friendly and economically effective option for maize growers of arid and semiarid regions to enhance the kernel yield and profit per annum. Poultry manure could be useful to ameliorate the adverse effects of salinity stress on all parameters, particularly the grain yield. Furthermore, this would be a useful and economical method for the safe disposal of byproducts.

Seed Priming Modulates Physiological and Agronomic Attributes of Maize (Zea mays L.) under Induced Polyethylene Glycol Osmotic Stress

Drought and osmotic stresses are major threats to agricultural crops as they affect plants during their life cycle. The seeds are more susceptible to these stresses during germination and establishment of seedlings. To cope with these abiotic stresses, various seed priming techniques have broadly been used. The present study aimed to assess seed priming techniques under osmotic stress. Osmo-priming with chitosan (1 and 2%), hydro-priming with distilled water, and thermo-priming at 4 °C were used on the physiology and agronomy of Zea mays L. under polyethylene glycol (PEG-4000)-induced osmotic stress (-0.2 and -0.4 MPa). The vegetative response, osmolyte content, and antioxidant enzymes of two varieties (Pearl and Sargodha 2002 White) were studied under induced osmotic stress. The results showed that seed germination and seedling growth were inhibited under osmotic stress and germination percentage, and the seed vigor index was enhanced in both varieties of Z. mays L. with chitosan osmo-priming. Osmo-priming with chitosan and hydro-priming with distilled water modulated the level of photosynthetic pigments and proline, which were reduced under induced osmotic stress; moreover, the activities of antioxidant enzymes were improved significantly. In conclusion, osmotic stress adversely affects the growth and physiological attributes; on the contrary, seed priming ameliorated the stress tolerance resistance of Z. mays L. cultivars to PEG-induced osmotic stress by activating the natural antioxidation enzymatic system and accumulating osmolytes.

Biostimulant red seaweed (Gracilaria tenuistipitata var. liui) extracts spray improves yield and drought tolerance in soybean

Drought has a deleterious impact on the growth, physiology, and yield of various plants, including soybean. Seaweed extracts are rich in various bioactive compounds, including antioxidants, and can be used as biostimulants for improving yield and alleviating the adverse effect of drought stress. The purpose of this study was to evaluate the effect of soybean growth and yield with different concentrations (0.0%, 5.0%, and 10.0% v/v) of water extracts of the red seaweed Gracilaria tenuistipitata var. liui under well-watered (80% of field capacity (FC) and drought (40% of FC)) conditions. Drought stress decreased soybean grain yield by 45.58% compared to well-watered circumstances but increased the water saturation deficit by 37.87%. It also decreased leaf water, chlorophyll content, plant height, and the fresh weight of the leaf, stem, and petiole. Drought stress decreased soybean grain yield by 45.58% compared to well-watered circumstances but increased the water saturation deficit by 37.87%. It also decreased leaf water, chlorophyll content, plant height, and the fresh weight of the leaf, stem, and petiole. Under both drought and well-watered situations, foliar application of seaweed extracts dramatically improved soybean growth and production. Under drought and well-watered situations, 10.0% seaweed extract increased grain yield by 54.87% and 23.97%, respectively in comparison to untreated plants. The results of this study suggest that red seaweed extracts from Gracilaria tenuistipitata var. liui may be used as a biostimulant to improve soybean yield and drought tolerance in the presence of insufficient water. However, the actual mechanisms behind these improvements need to be further investigated in field conditions.

Iron nanoparticle regulate succinate dehydrogenase activity in canola plants under drought stress

Application of nutrients as nanoparticle (NP) is an operative manner of nutrient supply for plants, especially under stress conditions. The present study was designed to highlight the role of iron NP on drought tolerance and elucidate the underlying mechanisms in drought-stressed canola plants. Drought stress was imposed by polyethylene glycol different concentrations (0, 10 and 15% (W/V)) with or without iron NP (1.5 and 3 mg/l). A comparative study of several physiological and biochemical parameters have been carried out in canola plants treated by drought and iron NP. Stressed-canola plants showed a reduction in growth parameters, whereas iron NP mostly stimulated growth of stressed plants, which was accompanied by reinforcement in defense mechanisms. Regarding impacts on compatible osmolytes, the data revealed that iron NP was able to regulate osmotic potential by increasing protein, proline and soluble sugar contents. The iron NP application was activated the enzymatic defense system (catalase and polyphenol oxidase) and promoted the non-enzymatic antioxidants (phenol, flavonol and flavonoid). Both of these adaptive responses declined free radicals as well as lipid peroxidation and enhanced the membrane stability and drought tolerance of the plants. Enhanced chlorophyll accumulation via induction of protoporphyrin, magnesium protoporphyrin and protochlorophyllide, by iron NP also contributed towards better stress tolerance. Enzymes of Krebs cycle, namely succinate dehydrogenase and aconitase, were induced by iron NP in canola plants grown under drought stress. These results propose a multifaceted involvement of iron NP, through regulation of activity of respiratory enzymes and antioxidant enzymes, production of reactive oxygen species, osmoregulation and secondary metabolites metabolism, in response to drought stress.

Efficacy of Naphthyl Acetic Acid Foliar Spray in Moderating Drought Effects on the Morphological and Physiological Traits of Maize Plants (Zea mays L.)

The threat of varying global climates has greatly driven the attention of scientists, as climate change increases the odds of worsening drought in many parts of Pakistan and the world in the decades ahead. Keeping in view the forthcoming climate change, the present study aimed to evaluate the influence of varying levels of induced drought stress on the physiological mechanism of drought resistance in selected maize cultivars. The sandy loam rhizospheric soil with moisture content 0.43-0.5 g g^-1, organic matter (OM) 0.43-0.55 g/kg, N 0.022-0.027 g/kg, P 0.028-0.058 g/kg, and K 0.017-0.042 g/kg was used in the present experiment. The findings showed that a significant drop in the leaf water status, chlorophyll content, and carotenoid content was linked to an increase in sugar, proline, and antioxidant enzyme accumulation at p < 0.05 under induced drought stress, along with an increase in protein content as a dominant response for both cultivars. SVI-I & II, RSR, LAI, LAR, TB, CA, CB, CC, peroxidase (POD), and superoxide dismutase (SOD) content under drought stress were studied for variance analysis in terms of interactions between drought and NAA treatment and were found significant at p < 0.05 after 15 days. It has been found that the exogenous application of NAA alleviated the inhibitory effect of only short-term water stress, but yield loss due to long-term osmotic stress will not be faced employing growth regulators. Climate-smart agriculture is the only approach to reduce the detrimental impact of global fluctuations, such as drought stress, on crop adaptability before they have a significant influence on world crop production.

Bacterial-Mediated Salinity Stress Tolerance in Maize (Zea mays L.): A Fortunate Way toward Sustainable Agriculture

Sustainable agriculture is threatened by salinity stress because of the low yield quality and low crop production. Rhizobacteria that promote plant growth modify physiological and molecular pathways to support plant development and reduce abiotic stresses. The recent study aimed to assess the tolerance capacity and impacts of Bacillus sp. PM31 on the growth, physiological, and molecular responses of maize to salinity stress. In comparison to uninoculated plants, the inoculation of Bacillus sp. PM31 improved the agro-morphological traits [shoot length (6%), root length (22%), plant height (16%), fresh weight (39%), dry weight (29%), leaf area (11%)], chlorophyll [Chl a (17%), Chl b (37%), total chl (22%)], carotenoids (15%), proteins (40%), sugars (43%), relative water (11%), flavonoids (22%), phenols (23%), radical scavenging capacity (13%), and antioxidants. The Bacillus sp. PM31-inoculated plants showed a reduction in the oxidative stress indicators [electrolyte leakage (12%), H2O2 (9%), and MDA (32%)] as compared to uninoculated plants under salinity and increased the level of osmolytes [free amino acids (36%), glycine betaine (17%), proline (11%)]. The enhancement of plant growth under salinity was further validated by the molecular profiling of Bacillus sp. PM31. Moreover, these physiological and molecular mechanisms were accompanied by the upregulation of stress-related genes (APX and SOD). Our study found that Bacillus sp. PM31 has a crucial and substantial role in reducing salinity stress through physiological and molecular processes, which may be used as an alternative approach to boost crop production and yield.

Shattering and yield expression of sesame (Sesamum indicum L) genotypes influenced by paclobutrazol concentration under rainfed conditions of Pothwar

Seed shattering is a critical challenge that significantly reduces sesame production by 50%. These shattering losses can be reduced by selecting shattering resistant genotypes or by incorporating modern agronomic management such as paclobutrazol, which can boost productivity and prevent seed shattering in sesame. Two-years of field trials were conducted to examine the effect of sesame genotypes, environment, and paclobutrazol (PBZ) concentrations. Twelve sesame genotypes were used in a four-way factorial RCBD with three replications and five PBZ concentrations (T₀ = Control; T₁ = 150; T₂ = 300; T₃ = 450; and T₄ = 600 mg L^- 1) under rainfed conditions of Pothwar. The findings revealed significant variations in the major effects of all examined variables (genotypes, locations, years, and PBZ levels). Sesame genotypes PI-154304 and PI-175907 had the highest plant height, number of capsule plant^- 1, seed capsule^- 1, 1000 seed weight, biological yield, and seed yield, while also having the lowest seed losses and shattering percentage. Regarding environments, NARC-Islamabad generated the highest plant height, number of capsule plant^- 1, shattering percentage, and biological yield; however, the URF-Koont produced the highest seed yield with the lowest shattering percentage. Additionally, plant height, capsules plant^- 1, and biological yield were higher in 2021, while seed capsule^- 1, 1000 seed weight, seed losses, shattering percentage, and seed yield were higher in 2020. PBZ concentration affected all measured parameters; plant height and number of seed capsule^- 1 decreased with increasing PBZ concentrations. 450 mg L^- 1 PBZ concentration generated the highest biomass, number of capsules plant^- 1, and seed yield. At the same time, PBZ concentration 600 mg L^- 1 generated the smallest plant, the lowest seed capsules^- 1, the greatest thousand seed weight, and the lowest shattering percentage. The study concluded that paclobutrazol could dramatically reduce shattering percentage and shattering losses while increasing economic returns through better productivity. Based on the findings, the genotypes PI-154304 and PI-175907 with paclobutrazol level 450 mgL^- 1 may be suggested for cultivation in Pothwar farming community under rainfed conditions, as they showed promising shattering resistance as well as enhanced growth and yield.

Biogenic synthesis of silver nanoparticles using Funaria hygrometrica Hedw. and their effects on the growth of Zea mays seedlings

The biogenic synthesis of silver nanoparticles (AgNPs) is an important step in developing eco-friendly and environmentally stable tools for ameliorating crop growth. In the current study, AgNPs were synthesized using Funaria hygrometrica and characterized using ultraviolet (UV) spectroscopy, scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD). The UV spectrum showed an absorption peak at 450 nm. SEM revealed an irregular and spherical morphology, FTIR spectroscopy indicated the presence of various functional groups, while XRD displayed peaks at 45.24°, 38.17°, 44.34°, 64.54°, and 57.48° 2θ. The effects of the F. hygrometrica-mediated AgNPs on maize growth and germination were assessed at 0, 100, 300, and 500 ppm. The germination percentage and relative germination rate were increased to 95% ± 1.83% and 100% ± 2.48% at 100 ppm of synthesized AgNPs and then declined at 300 and 500 ppm. The length, fresh weight, and dry matter of the root, shoot, and seedlings were highest at 100 ppm NPs. The plant height, root length, and dry matter stress tolerance indices were also the highest (112.3%, 118.7%, and 138.20% compared with the control) at 100 ppm AgNPs. Moreover, the growth of three maize varieties, that is, NR-429, NR-449, and Borlog, were assessed at 0, 20, 40, and 60 ppm F. hygrometrica-AgNPs. The results indicated the highest root and shoot length at 20 ppm AgNPs. In conclusion, seed priming with AgNPs enhances the growth and germination of maize and can ameliorate crop production globally. RESEARCH HIGHLIGHTS: Funaria hygrometrica Hedw.-mediated AgNPs were synthesized and characterized. Biogenic AgNPs influenced the growth and germination of maize seedlings. All growth parameters were highest at 100 ppm synthesized NPs.

Salinity stress improves antioxidant potential by modulating physio-biochemical responses in Moringa oleifera Lam

Moringa oleifera Lam. is a common edible plant, famous for several nutritional and therapeutic benefits. This study investigates the salt -induced modulations in plant growth, physio-biochemical responses, and antioxidant performance of M. oleifera grown under 0, 50, and 100 mM NaCl concentrations. Results showed that the plant effectively managed moderate salinity (50 mM NaCl) by maintaining succulence, weight ratios, and biomass allocation patterns of both shoot and root with minimal reduction in dry biomass. However, high salinity (100 mM NaCl) remarkably declined all growth parameters. The plant accumulated more Na⁺ and Cl^-, while less K⁺ under salinity as compared to the control. Consequently, osmotic potentials of both root and leaf decreased under salinity, which was corroborated by the high amount of proline and soluble sugars. Increased level of H₂O₂ with significantly unchanged membrane fluidity indicating its role in perceiving and managing stress at moderate salinity. In addition, increased activities of superoxide dismutase, and catalase, with increased glutathione and flavonoid contents suggest an integrated participation of both enzymatic and non-enzymatic antioxidant components in regulating ROS. On the other hand, high salinity caused an outburst of ROS indicated by high H₂O₂, MDA, and electrolyte leakage. As a response, moringa drastically increased the activities of all antioxidant enzymes and contents of antioxidant molecules including ascorbic acid, glutathione, total phenols, and flavonoids with high radical scavenging and reducing power capacities. However, a considerable amount of energy was used in such management resulting in a significant growth reduction at 100 mM NaCl. This study suggests that moringa effectively resisted moderate salinity by modulating physio-biochemical attributes and effectively managing ion toxicity and oxidative stress. Salt stress also enhanced the medicinal potentials of moringa by increasing the contents of antioxidant compounds including ascorbic acid, glutathione, total phenols, and flavonoids and their resulting activities. It can be grown on degraded/ saline lands and biomass of this plant can be used for edible and medicinal purposes, besides providing other benefits in a global climate change scenario.

Influence of foliar spray and post-harvest treatments on head yield, shelf-life, and physicochemical qualities of broccoli

Rapid senescence is the key factor in the deterioration of post-harvest shelf-life in broccoli heads. This study evaluates the head yield and its related traits, and physicochemical attributes of broccoli under four foliar sprays of mineral nutrients (B, Zn, Mo, and B + Zn + Mo) with control. The interaction effects of shelf-life and physicochemical attributes of broccoli for these five pre-harvest and five post-harvest storage treatments (LDP bag, HDP vacuum pack, 2% eggshell powder solution, 2% ascorbic acid, and control) both at cold storage and room temperature were evaluated with three replications. The significantly higher marketable head yield of 28.02 t ha^-1, maximum gross return [(Bangladesh Taka (BDT 420300 ha^-1)], net return (BDT 30565 ha^-1), and maximum benefit-cost ratio (BCR) of 3.67 were obtained from the pre-harvest foliar application of B + Zn + Mo in broccoli. Pre-harvest foliar spray of combined nutrient B + Zn + Mo and post-harvest treatment high-density polyethylene (HDP, 15 μm) vacuum packaging efficiently improve post-harvest physicochemical attributes, viz., compactness, green color, texture, carbohydrates, fats, energy, antioxidants, vitamin C, and total phenols in broccoli head compared to the rest of the treatment combinations. In addition, this treatment combination also confirmed a maximum shelf-life of 24.55 days at cold storage [relative humidity (RH) 90-95% and 4°C] and 7.05 days at room temperature (RH 60-65% and 14-22°C) compared to the rest of the treatment combinations. Therefore, we recommend a pre-harvest foliar spray of combined nutrient elements B + Zn + Mo and an HDP (15 μm) vacuum post-harvest packaging for the maximum benefits for both farmers and consumers to get the best head yield, anticipated physicochemical attributes, and maximum shelf-life of broccoli.

Combined application of plant growth-promoting bacteria and iron oxide nanoparticles ameliorates the toxic effects of arsenic in Ajwain (Trachyspermum ammi L.)

Soil contamination with toxic heavy metals [such as arsenic (As)] is becoming a serious global problem because of the rapid development of the social economy. Although plant growth-promoting bacteria (PGPB) and nanoparticles (NPs) are the major protectants to alleviate metal toxicity, the study of these chemicals in combination to ameliorate the toxic effects of As is limited. Therefore, the present study was conducted to investigate the combined effects of different levels of Providencia vermicola (5 ppm and 10 ppm) and iron oxide nanoparticles (FeO-NPs) (50 mg/l^-1 and 100 mg/l^-1) on plant growth and biomass, photosynthetic pigments, gas exchange attributes, oxidative stress and response of antioxidant compounds (enzymatic and non-enzymatic), and their specific gene expression, sugars, nutritional status of the plant, organic acid exudation pattern As accumulation from the different parts of the plants, and electron microscopy under the soil, which was spiked with different levels of As [0 μM (i.e., no As), 50 μM, and 100 μM] in Ajwain (Trachyspermum ammi L.) seedlings. Results from the present study showed that the increasing levels of As in the soil significantly (p< 0.05) decreased plant growth and biomass, photosynthetic pigments, gas exchange attributes, sugars, and nutritional contents from the roots and shoots of the plants, and destroyed the ultra-structure of membrane-bound organelles. In contrast, increasing levels of As in the soil significantly (p< 0.05) increased oxidative stress indicators in term of malondialdehyde, hydrogen peroxide, and electrolyte leakage, and also increased organic acid exudation patter in the roots of T. ammi seedlings. The negative impact of As toxicity can overcome the application of PGPB (P. vermicola) and FeO-NPs, which ultimately increased plant growth and biomass by capturing the reactive oxygen species, and decreased oxidative stress in T. ammi seedlings by decreasing the As contents in the roots and shoots of the plants. Our results also showed that the FeO-NPs were more sever and showed better results when we compared with PGPB (P. vermicola) under the same treatment of As in the soil. Research findings, therefore, suggest that the combined application of P. vermicola and FeO-NPs can ameliorate As toxicity in T. ammi seedlings, resulting in improved plant growth and composition under metal stress, as depicted by balanced exudation of organic acids.

Agronomic biofortification of food crops: An emerging opportunity for global food and nutritional security

Fortification of food with mineral micronutrients and micronutrient supplementation occupied the center stage during the two-year-long Corona Pandemic, highlighting the urgent need to focus on micronutrition. Focus has also been intensified on the biofortification (natural assimilation) of mineral micronutrients into food crops using various techniques like agronomic, genetic, or transgenic. Agronomic biofortification is a time-tested method and has been found useful in the fortification of several nutrients in several crops, yet the nutrient use and uptake efficiency of crops has been noted to vary due to different growing conditions like soil type, crop management, fertilizer type, etc. Agronomic biofortification can be an important tool in achieving nutritional security and its importance has recently increased because of climate change related issues, and pandemics such as COVID-19. The introduction of high specialty fertilizers like nano-fertilizers, chelated fertilizers, and water-soluble fertilizers that have high nutrient uptake efficiency and better nutrient translocation to the consumable parts of a crop plant has further improved the effectiveness of agronomic biofortification. Several new agronomic biofortification techniques like nutripriming, foliar application, soilless activation, and mechanized application techniques have further increased the relevance of agronomic biofortification. These new technological advances, along with an increased realization of mineral micronutrient nutrition have reinforced the relevance of agronomic biofortification for global food and nutritional security. The review highlights the advances made in the field of agronomic biofortification via the improved new fertilizer forms, and the emerging techniques that achieve better micronutrient use efficiency of crop plants.

Salt Eustress Induction in Red Amaranth (Amaranthus gangeticus) Augments Nutritional, Phenolic Acids and Antiradical Potential of Leaves

Earlier researchers have highlighted the utilization of salt eustress for boosting the nutritional and phenolic acid (PA) profiles and antiradical potential (ARP) of vegetables, which eventually boost food values for nourishing human diets. Amaranth is a rapidly grown, diversely acclimated C4 leafy vegetable with climate resilience and salinity resistance. The application of salinity eustress in amaranth has a great scope to augment the nutritional and PA profiles and ARP. Therefore, the A. gangeticus genotype was evaluated in response to salt eustress for nutrients, PA profile, and ARP. Antioxidant potential and high-yielding genotype (LS1) were grown under four salt eustresses (control, 25 mM, 50 mM, 100 mM NaCl) in a randomized completely block design (RCBD) in four replicates. Salt stress remarkably augmented microelements, proximate, macro-elements, phytochemicals, PA profiles, and ARP of A. gangeticus leaves in this order: control < low sodium chloride stress (LSCS) < moderate sodium chloride stress (MSCS) < severe sodium chloride stress (SSCS). A large quantity of 16 PAs, including seven cinnamic acids (CAs) and nine benzoic acids (BAs) were detected in A. gangeticus genotypes. All the microelements, proximate, macro-elements, phytochemicals, PA profiles, and ARP of A. gangeticus under MSCS, and SSCS levels were much higher in comparison with the control. It can be utilized as preferential food for our daily diets as these antiradical compounds have strong antioxidants. Salt-treated A. gangeticus contributed to excellent quality in the end product in terms of microelements, proximate, macro-elements, phytochemicals, PA profiles, and ARP. A. gangeticus can be cultivated as an encouraging substitute crop in salt-affected areas of the world.

Plant Microbiome Engineering: Hopes or Hypes

Rhizosphere microbiome is a dynamic and complex zone of microbial communities. This complex plant-associated microbial community, usually regarded as the plant's second genome, plays a crucial role in plant health. It is unquestioned that plant microbiome collectively contributes to plant growth and fitness. It also provides a safeguard from plant pathogens, and induces tolerance in the host against abiotic stressors. The revolution in omics, gene-editing and sequencing tools have somehow led to unravel the compositions and latent interactions between plants and microbes. Similarly, besides standard practices, many biotechnological, (bio)chemical and ecological methods have also been proposed. Such platforms have been solely dedicated to engineer the complex microbiome by untangling the potential barriers, and to achieve better agriculture output. Yet, several limitations, for example, the biological obstacles, abiotic constraints and molecular tools that capably impact plant microbiome engineering and functionality, remained unaddressed problems. In this review, we provide a holistic overview of plant microbiome composition, complexities, and major challenges in plant microbiome engineering. Then, we unearthed all inevitable abiotic factors that serve as bottlenecks by discouraging plant microbiome engineering and functionality. Lastly, by exploring the inherent role of micro/macrofauna, we propose economic and eco-friendly strategies that could be harnessed sustainably and biotechnologically for resilient plant microbiome engineering.

Short-term responses of Spinach (Spinacia oleracea L.) to the individual and combinatorial effects of Nitrogen, Phosphorus and Potassium and silicon in the soil contaminated by boron

While of lesser prevalence than boron (B) deficient soils, B-rich soils are important to study as they can cause B toxicity in the field and subsequently decrease crop yields in different regions of the world. We have conducted the present study to examine the role of the individual or combined application of silicon (Si) and NPK fertilizer in B-stressed spinach plants (Spinacia oleracea L.). S. oleracea seedlings were subjected to different NPK fertilizers, namely, low NPK (30 kg ha-2) and normal NPK (60 kg ha-2)], which were also supplemented by Si (3 mmol L-1), for varying levels of B in the soil i.e., 0, 250, and 500 mg kg-1. Our results illustrated that the increasing levels of B in the soil caused a substantial decrease in the plant height, number of leaves, number of stems, leaf area, plant fresh weight, plant dry weight, chlorophyll a, chlorophyll b, total chlorophyll, carotenoid content, net photosynthesis, stomatal conductance, transpiration rate, magnesium content in the roots, magnesium contents in the shoots, phosphorus content in the roots, phosphorus content in the leaves in the shoots, iron content in the roots, iron content in the shoots, calcium content in the roots, and calcium content in the shoots. However, B toxicity in the soil increased the concentration of malondialdehyde, hydrogen peroxide, and electrolyte leakage which were also manifested by the increasing activities of enzymatic [superoxidase dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX)], and non-enzymatic antioxidants (phenolic, flavonoid, ascorbic acid, and anthocyanin content). B toxicity in the soil further increased the concentration of organic acids in the roots such as oxalic acid, malic acid, formic acid, citric acid, acetic acid, and fumaric acid. The addition of Si and fertilizer levels in the soil significantly alleviated B toxicity effects on S. oleracea by improving photosynthetic capacity and ultimately plant growth. The increased activity of antioxidant enzymes in Si and NPK-treated plants seems to play a role in capturing stress-induced reactive oxygen species, as was evident from the lower levels of oxidative stress indicators, organic acid exudation, and B concentration in the roots and shoots of Si and NPK-treated plants. Research findings, therefore, suggested that the Si and NPK application can ameliorate B toxicity in S. oleracea seedlings and result in improved plant growth and composition under metal stress as depicted by the balanced exudation of organic acids.

Impact of Plantago ovata Forsk leaf extract on morpho-physio-biochemical attributes, ions uptake and drought resistance of wheat (Triticum aestivum L.) seedlings

The present study was conducted to examine the potential role of Plantago ovata Forsk leaf extract (POLE) which was applied at various concentration levels (control, hydropriming, 10, 20, 30, and 40% POLE) to the wheat (Triticum aestivum L.) seedlings. Drought stressed was applied at 60% osmotic potential (OM) to the T. aestivum seedlings to study various parameters such as growth and biomass, photosynthetic pigments and gas exchange characteristics, oxidative stress and response of various antioxidants and nutritional status of the plants. Various growth parameters such as gaseous exchange attributes, antioxidants and nutritional status of T. aestivum were investigated in this study. It was evident that drought-stressed condition had induced a negative impact on plant growth, photosynthetic pigment, gaseous exchange attributes, stomatal properties, and ion uptake by different organs (roots and shoots) of T. aestivum. The decrease in plant growth resulted from oxidative stress and overcome by the antioxidant (enzymatic and non-enzymatic) compounds, since their concentration increased in response to dehydration. Seed priming with POLE positively increased plant growth and photosynthesis, by decreasing oxidative stress indicators and increasing activities of antioxidant (enzymatic and non-enzymatic) compounds, compared to the plants which were grown without the application of POLE. Our results also depicted that optimum concentration of POLE for T. aestivum seedlings under drought condition was 20%, while further increase in POLE (30 and 40%) induced a non-significant (P < 0.05) effect on growth (shoot and root length) and biomass (fresh and dry weight) of T. aestivum seedling. Here we concluded that the understanding of the role of seed priming with POLE in the increment of growth profile, photosynthetic measurements and nutritional status introduces new possibilities for their effective use in drought-stressed condition and provides a promising strategy for T. aestivum tolerance against drought-stressed condition.

New opportunities in plant microbiome engineering for increasing agricultural sustainability under stressful conditions

Plant microbiome (or phytomicrobiome) engineering (PME) is an anticipated untapped alternative strategy that could be exploited for plant growth, health and productivity under different environmental conditions. It has been proven that the phytomicrobiome has crucial contributions to plant health, pathogen control and tolerance under drastic environmental (a)biotic constraints. Consistent with plant health and safety, in this article we address the fundamental role of plant microbiome and its insights in plant health and productivity. We also explore the potential of plant microbiome under environmental restrictions and the proposition of improving microbial functions that can be supportive for better plant growth and production. Understanding the crucial role of plant associated microbial communities, we propose how the associated microbial actions could be enhanced to improve plant growth-promoting mechanisms, with a particular emphasis on plant beneficial fungi. Additionally, we suggest the possible plant strategies to adapt to a harsh environment by manipulating plant microbiomes. However, our current understanding of the microbiome is still in its infancy, and the major perturbations, such as anthropocentric actions, are not fully understood. Therefore, this work highlights the importance of manipulating the beneficial plant microbiome to create more sustainable agriculture, particularly under different environmental stressors.

Thiourea-Capped Nanoapatites Amplify Osmotic Stress Tolerance in Zea mays L. by Conserving Photosynthetic Pigments, Osmolytes Biosynthesis and Antioxidant Biosystems

Salinity is one of the most prevalent abiotic stresses which not only limits plant growth and yield, but also limits the quality of food products. This study was conducted on the surface functionalization of phosphorus-rich mineral apatite nanoparticles (ANPs), with thiourea as a source of nitrogen (TU-ANPs) and through a co-precipitation technique for inducing osmotic stress tolerance in Zea mays. The resulting thiourea-capped apatite nanostructure (TU-ANP) was characterized using complementary analytical techniques, such as EDX, SEM, XRD and IR spectroscopy. The pre-sowing of soaked seeds of Zea mays in 1.00 µg/mL, 5.00 µg/mL and 10 µg/mL of TU-ANPs yielded growth under 0 mM, 60 mM and 100 mM osmotic stress of NaCl. The results show that Ca and P salt acted as precursors for the synthesis of ANPs at an alkaline pH of 10-11. Thiourea as a source of nitrogen stabilized the ANPs' suspension medium, leading to the synthesis of TU-ANPs. XRD diffraction analysis validated the crystalline nature of TU-ANPs with lattice dimensions of 29 nm, calculated from FWHM using the Sherrer equation. SEM revealed spherical morphology with polydispersion in size distribution. EDS confirmed the presence of Ca and P at a characteristic KeV, whereas IR spectroscopy showed certain stretches of binding functional groups associated with TU-ANPs. Seed priming with TU-ANPs standardized germination indices (T50, MGT, GI and GP) which were significantly declined by NaCl-based osmotic stress. Maximum values for biochemical parameters, such as sugar (39.8 mg/g at 10 µg/mL), protein (139.8 mg/g at 10 µg/mL) and proline (74.1 mg/g at 10 µg/mL) were recorded at different applied doses of TU-ANP. Antioxidant biosystems in the form of EC 1.11.1.6 catalase (11.34 IU/g FW at 10 µg/mL), EC 1.11.1.11 APX (0.95 IU/G FW at 10 µg/mL), EC 1.15.1.1 SOD (1.42 IU/g FW at 5 µg/mL), EC 1.11.1.7 POD (0.43 IU/g FW at 5 µg/mL) were significantly restored under osmotic stress. Moreover, photosynthetic pigments, such as chlorophyll A (2.33 mg/g at 5 µg/mL), chlorophyll B (1.99 mg/g at 5 µg/mL) and carotenoids (2.52 mg/g at 10 µg/mL), were significantly amplified under osmotic stress via the application of TU-ANPs. Hence, the application of TU-ANPs restores the growth performance of plants subjected to induced osmotic stress.