Aug 2026· International Journal of Plant & Soil Science· Vol 38, pp. 554-578· 0 citations
Abstract
Water deficit during germination and early establishment restricts imbibition, delays reserve mobilisation and impairs stand formation, making the seed stage an attractive target for low-input stress management. Melatonin-based seed treatment has consequently moved from an experimental curiosity to a widely studied chemical-priming approach. This critical narrative review evaluates the physiological and molecular mechanisms through which melatonin applied before sowing may mitigate water stress, while separating mechanistic plausibility from agronomic proof. Literature published from 1995 to 1 June 2026 was identified through accessible scholarly indexes, citation searching and DOI-level verification. Evidence was appraised according to stress realism, priming controls, dose definition, genotype coverage, developmental duration, mechanistic depth and field relevance. Across cucumber, rapeseed, soybean, safflower, triticale, rice, maize, peanut, wheat, cotton and foxtail millet, melatonin treatment generally improved germination, seedling vigour, membrane stability and antioxidant capacity under polyethylene glycol-induced osmotic stress or restricted water supply. The most reproducible mechanism is redox buffering: melatonin moderates damaging reactive oxygen species accumulation while preserving the signalling functions required for germination, supported by enhanced enzymatic and non-enzymatic antioxidant systems. Osmotic adjustment, reserve mobilisation, root development, stomatal regulation, chloroplast protection and crosstalk with abscisic acid, gibberellins, nitric oxide and sugar metabolism provide additional, but unevenly substantiated, explanations. Emerging evidence implicates phytomelatonin receptor-mediated signalling, methylglyoxal detoxification and autophagy. Confidence in broad agronomic claims remains limited because most studies use short-term laboratory assays, heterogeneous concentrations and polyethylene glycol models that do not reproduce soil–plant–atmosphere drought. Rare field studies indicate possible gains in yield and water productivity, but independent multi-environment validation, treatment standardisation, storage testing, cost analysis and regulatory assessment are inadequate. Melatonin seed treatment is therefore best regarded as a promising, biologically credible priming technology whose practical value depends on crop-specific dose optimisation and evidence extending beyond early seedling biomarkers.
Drought increasingly constrains global wheat production, reducing photosynthetic capacity, accelerating senescence, and shortening grain-filling periods. This review analyses current knowledge on physiological responses (root architecture, reactive oxygen species dynamics, photosystem stability, and abscisic acid signaling) and evaluates agronomic, chemical, nutritional, and genetic countermeasures that aim to protect yield under water deficit. We compare evidence from controlled experiments and field trials to assess which interventions deliver consistent yield benefits, and we highlight trade-offs between water conservation and carbon assimilation. Root traits that access deeper soil moisture, robust antioxidant systems, and balanced hormonal regulation emerge as key biological targets; meanwhile, seed priming, targeted nutrient management, and selected biochemical treatments show promise as near-term, scalable practices. Genetic approaches, including marker-assisted selection and introgression of drought-adaptive alleles, offer longer-term gains but require multi-environment validation. We identify gaps in cross-scale evidence, notably a shortage of multi-location, farmer-level trials that quantify the cost-effectiveness and environmental safety of chemical agents. Finally, we propose an integrated research agenda combining trait-based breeding, optimized nutrient regimes, and pragmatic agronomy to improve wheat resilience to drought. Implementing coordinated strategies across breeding and management is essential to sustain wheat yields as climate variability intensifies.
Rei Waki, Chayara Salsabila, Kiyoka Sakamoto et al.· BIO Web of Conferences· 0 citations
Nanotechnology offers transformative potential for mitigating drought stress in cereal crops, yet translation from controlled environments to field applications remains constrained by inconsistent outcomes, limited mechanistic understanding, and insufficient environmental risk assessment. This review critically synthesizes recent advances in nanoparticle (NP)-mediated drought resilience across wheat (Triticum aestivum), maize (Zea mays), and rice (Oryza sativa), with emphasis on mechanistic dissection of NP-plant interactions, species-specific responses, and translational pathways. We systematically evaluate metal/metal oxide, silicon-based, carbon-based, and polymer/bio-based NPs, distinguishing where evidence permits between particle-specific surface effects and ion-derived contributions. Quantitative concentration thresholds for optimal drought mitigation and toxicity limits are provided, revealing narrow hormetic windows that vary markedly with crop physiology, root architecture, and silicon uptake capacity. Mechanistically, NPs modulate interconnected networks governing water relations, photosynthetic efficiency, antioxidant defense, osmotic adjustment, and phytohormonal signaling, with transcriptomic evidence indicating reprogramming of stress-responsive genes. We propose a trait-based translational framework linking NP physicochemical properties to quantifiable phenotypic targets with integrated environmental risk gates addressing NP persistence, dissolution kinetics, soil microbial impacts, and biosafety. Critical research gaps include: (i) rigorous separation of particle-specific from ionic mechanisms through appropriate controls; (ii) crop- and stress-specific dose calibration; (iii) long-term field validation under climate-change relevant drought scenarios; and (iv) ecotoxicological assessment in dryland agroecosystems. This review provides a mechanistic roadmap for developing sustainable, field-applicable nano-enabled strategies that balance agronomic benefits against ecological safety in climate-resilient cereal production.
Melatonin (N-acetyl-5-methoxytryptamine) is a regulatory molecule with potential to increase plant tolerance to water stress by modulating stomatal function, redox balance, and photosynthetic efficiency. However, its physiological effects depend on dose, species, and stress intensity, and studies on Coffea canephora under recurrent drought are scarce. This study evaluated the effects of exogenous melatonin (0, 100, 200, 300, and 400 µM) on young plants of conilon coffee genotype 02 (Clone V12) subjected to three consecutive cycles of water deficit and rehydration. The experiment was conducted in a greenhouse using a randomized block design, with evaluations of gas exchange, water potential, and biomass allocation. Melatonin improved physiological recovery after rehydration, particularly at 100 and 300 µM during the second stress cycle, when photosynthesis reached values similar to the irrigated control. The 400 µM treatment maintained root dry mass close to the control under prolonged deficit, suggesting preferential biomass allocation to the root system. Overall, melatonin effects were more pronounced during recovery than stress, indicating a possible priming action. These results highlight the potential of melatonin as a phytoprotective agent in C. canephora, although responses depend on dose and stress cycle.
Soil salinity is a major environmental constraint that threatens global food security by significantly inhibiting seed germination and early seedling establishment. Salinity disrupts all three phases of seed germination: Phase I (imbibition), where reduced water absorption capacity reduces seed hydration and delays metabolic reactivation; Phase II (lag phase), where ionic toxicity and oxidative stress impair enzyme activity, reserve mobilization, and cellular metabolism; and Phase III (radicle protrusion), where limited cell division and length prevent radicle emergence and seedling establishment. These disturbances reduce germination percentage, germination rate, germination index, germination energy, and plant vigor, while increasing average germination time. At the morpho-physiological level, salinity impairs water absorption, membrane stability, photosynthetic pigment accumulation, and root–shoot development. Biochemically, excessive accumulation of reactive oxygen species (ROS), hydrogen peroxide (H2O2), and malondialdehyde (MDA) causes cellular damage and metabolic dysfunction. At the molecular level, salinity alters the expression of the aquaporin gene family (PIPs, TIPs, NIPs, and SIPs), suppresses starch mobilization by reducing α-amylase, enhances abscisic acid (ABA) signaling, and inhibits gibberellic acid (GA) biosynthesis, all of which cause inhibition of germination and early growth. As a result, an effective strategy is needed to improve seed germination under saline conditions. Therefore, the second focus of this review is to critically evaluate the potential of nanoparticles (NPs) and nanobiochar (NBC) as emerging tools to mitigate salinity stress during seed germination. Current evidence suggests that NPs and NBC enhance water absorption, maintain membrane strength, improve nutrient availability, promote antioxidant defense systems, and regulate osmotic adjustment in saline environments. Furthermore, these nanomaterials alter key molecular pathways involved in aquaporin expression, hormonal homeostasis, and reserve mobilization, thereby promoting successful germination and seedling establishment. By combining recent advances in physiological, biochemical, and molecular research, this review provides a comprehensive understanding of salinity-induced germination disruption and highlights the potential of NP- and NBC-based approaches to improve crop establishment under saline conditions.
Abhishek Singh, R. Singh, Mirela-Alina Sandu et al.· Nanomaterials· 0 citations
Biostimulant-rich plant extracts offer a sustainable agricultural strategy to mitigate plant stress. Two-year field experiments (2024-2025) evaluated maize seed priming with maize silk extract (MSE) at 5%, 10%, and 15% (based on dry weight) under normal (NC, ECe=1.48 dS m⁻¹) and saline (SC, ECe=8.90 dS m⁻¹) conditions. SC significantly impaired photosynthesis, leaf integrity, and nutritional balance, ultimately reducing plant growth and grain yield. These detrimental effects were driven by elevated oxidative stress (superoxide and H2O2) and cellular damage (electrolyte leakage and malondialdehyde). Consequently, stressed plants exhibited basal increases in osmolytes, enzymatic (SOD, CAT, POD, APX, and GR) and non-enzymatic antioxidants, the expression of targeted ion-transport genes (SOS1 and NHX2), and total antioxidant activity. However, MSE seed priming significantly alleviated salinity-induced damage. The 10% MSE concentration emerged as the most effective treatment. Under SC, it remarkably enhanced photosynthesis indicators, leaf integrity, essential nutrient contents, and the K⁺/Na⁺ ratio. Consequently, overall plant growth and grain yield increased significantly. These agronomic improvements were mechanistically linked to a pronounced reduction in oxidative stress and cellular damage. Furthermore, the 10% MSE treatment synergistically boosted osmoregulators, antioxidant compounds, defensive enzyme activities, the expression of these specific ion-homeostasis genes, and total antioxidant capacity compared to unprimed plants. These biochemical and targeted transcriptional enhancements were also observed under NC. Conclusively, seed priming with 10% MSE orchestrates a robust, multi-tiered defense system against salinity stress. This highly effective and sustainable approach maximizes maize productivity in saline environments, ultimately contributing to future global food security.
Amany H. A. Abeed, H. Alharby, E. Belal et al.· Plant Science· 0 citations
ABSTRACT Water deficit stress is one of the main plant growth and productivity limitation factors. In current study, the Crocus sativus plants were exposed to three irrigation regimes (FC 100%, FC 75%, and FC 25%) combined with ZnO‐NPs (0, 25, and 50 mg L−1) and MgSO4 (0, 1.5, and 3 g L−1). Growth, flowering, physiological, and biochemical characteristics were evaluated in a split‐plot experiment based on randomized complete block design (RCBD) with three replicates during 2023–2024. The results demonstrated that severe drought stress markedly reduced leaf dry weight, flower weight, flower number, stigma dry weight, and corm production, while increasing ionic leakage, catalase activity, and proline accumulation. The combined application of ZnO‐NPs and MgSO4 improved relative water content, photosynthetic efficiency, antioxidant activity, vegetative growth, and flowering performance under full irrigation and mild water deficit (75% FC) conditions, while under severe drought (25% FC), these treatments especially ZnO‐NPs intensified plant stress. CAT activity and proline content increased considerably in response to ZnO‐NPs 50 mg L−1 × MgSO4 3 g L−1 under FC 75% and FC 25%. Application of ZnO‐NPs and MgSO4 effectively alleviated drought‐induced damages under moderate irrigation (FC 75%) and enhanced plant tolerance to water stress. Results of PCA and Cluster analysis proved that application of ZnO‐NPs at 50 mg L−1 + MgSO4 3 g L−1 provide the most balanced improvement in growth, flowering, and stress tolerance traits under mild drought stress.
Laila Turki, Seham Zaben, Ekhlas Meteab Ahmed Marir et al.· Food Science & Nutrition· 0 citations
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