A Review on Chitosan Nanoparticles as a Biostimulant and Their Applications in Agriculture

Sustainably advancing plant physiology through chitosan nanoformulations

Modern agriculture faces significant challenges due to excessive agrochemical use, resulting in environmental degradation and reduced sustainability. Bionanomaterials have emerged as eco-friendly alternatives, among which chitosan is widely recognised for its biodegradability, biocompatibility and multifunctional properties. This review demonstrates findings from recent studies (2015–25), highlighting that conventional nutrient use efficiency remains below 50 % for macronutrients and < 5 % for micronutrients, whereas chitosan-based nanomaterials (NMs) significantly enhance nutrient delivery and utilisation. These NMs function as nanofertilisers, nanocarriers, biostimulants and nanopesticides, improving nutrient uptake, enzymatic activity, stress tolerance and overall plant growth. From a physiological perspective, they enable controlled release, targeted delivery and modulation of metabolic processes, thereby enhancing crop productivity while reducing agrochemical dependence. However, key challenges persist, including limited field-scale validation, lack of long-term environmental safety data and absence of standardised formulations. Future research should focus on large-scale validation, mechanistic insights and integration with precision agriculture. Overall, chitosan-based nanotechnology offers a promising and sustainable strategy for advancing plant physiology, though its successful field application requires further validation and standardisation.

Biostimulants for Sustainable and Resilient Agriculture

The growing pressure exerted by global food demand, combined with the excessive use of chemical and synthetic inputs, is prompting the agricultural sector to seek innovative and sustainable solutions to improve, or at least maintain, crop yields in a context of increased abiotic stress linked to climate change. Among the promising approaches, biostimulants are attracting growing interest, particularly those derived from natural sources such as seaweed extracts, humic acids, and beneficial microorganisms. These products work through various mechanisms, including osmotic regulation, activation of antioxidant systems, stimulation of root growth, and improvement of nutrient absorption. Many recent research and review articles have explored the optimal combinations of raw materials, formulation processes, target crops, and environmental conditions to maximize beneficial effects on plant growth, soil health, and tolerance to abiotic stresses. As a result, a growing range of commercial products is emerging, with diverse chemical compositions, formulations, and modes of application. However, the precise relationships between the biochemical composition of biostimulants and their physiological effects remain poorly understood, suggesting a key role for molecular synergies. This review provides a concise overview of recent advances in biostimulant research and their potential to enhance food security by improving crop resilience in the context of climate change.

Microbe-mediated nanotechnology for heavy metal detoxification and crop resilience: mechanisms, advances, and future prospects

Microbial nanotechnology provides a simple, reliable, and eco-friendly method for synthesizing various types of nanoparticles (NPs) by utilizing microorganisms, including viruses, fungi, bacteria, and algae, to manufacture and functionalize them. It has extensive applications in various industries, including electronics, healthcare, food production, environmental science, and agriculture. Environmental shifts have greatly influenced global crop production. Abiotic stresses, including heat, UV radiation, salinity, cold, drought, and heavy metals (HMs), adversely affect crop development and yield production. Nanotechnologies are known as powerful tools for crop improvement, aiming to increase crop yield and stress tolerance. Microbially produced NPs can reduce stress-induced impairments and promote plant development in challenging environments. In this context, microbial-mediated NPs act as multifunctional agents that can modulate plant stress responses, improve nutrient availability, and reduce metal toxicity in soil-plant systems. The recent review highlights a comprehensive overview of microbial NPs synthesis, with a particular focus on the mechanisms underlying NPs formation, NPs-HMs interactions, and their role in improving crop resilience. It further highlights recent advances in microbe-mediated nanotechnology for sustainable agriculture and critically discusses current limitations, including scalability, environmental safety, and field-level application challenges. Finally, future perspectives are presented to bridge the gap between laboratory research and practical agricultural implementation.

Unlocking the potential of brown algae as a biostimulant and its role in disease resistance and stress tolerance in crop plants

Brown algal extracts increase crop yield by stimulating growth and enhancing resistance to environmental stress, making them a sustainable and effective biostimulant for modern agriculture. Population growth, climate change, and intensive agrochemical use pose significant challenges to environmental sustainability and food security. Seaweeds, particularly brown algae, have attracted considerable attention as promising biostimulants for sustainable agricultural applications. Brown algae, the second most prevalent group of marine macroalgae, are rich in polysaccharides (alginates, fucoidans, and laminarins), vitamins, minerals, and polyphenols, which contribute to their biostimulant properties. Previous studies have provided important insights into the mechanisms of action of seaweed extracts and the physiological and biochemical changes they induce in crop plants. Although the molecular mechanisms underlying the effects of seaweed biostimulants remain incompletely understood, recent research efforts have substantially advanced our understanding of their functional roles. This review discusses conventional and advanced extraction techniques used to obtain bioactive compounds from seaweeds. In addition, it examines the composition of brown algae and their roles in promoting plant growth, development, and stress tolerance in various crop species. Furthermore, this review highlights the molecular mechanisms underlying growth promotion, biotic stress resistance, and abiotic stress tolerance in brown algae-treated plants, along with key findings from recent metabolomics studies. The use of brown algal extracts or their components influences crop plants by enhancing nutrient uptake, regulating phytohormone signalling, boosting antioxidant defence, facilitating osmotic adjustment, and stimulating stress-responsive genes and pathways. Collectively, these properties highlight the potential of brown algae-derived biostimulants to support sustainable agriculture by reducing the need for synthetic agrochemicals while increasing food security amid growing environmental challenges.

Harnessing magnesium nanoparticles for enhanced crop growth and stress mitigation

Exogenous Application of Cellulose-Based Materials for Improved Plant Fitness

Exogenous application of bio-based nanomaterials provides a targeted strategy to modulate plant physiological and biochemical responses. This review synthesizes recent advancements in the foliar application of nanocellulose (NC), in particular, cellulose nanocrystals (CNC) and cellulose nanofibers (CNF), to enhance plant fitness. CNC-formed films provide physical and biochemical barriers that increase plant drought and cold stress tolerance. Topically applied CNC reduce non-stomatal transpiration and serve as insulators, allowing the flowering buds to successfully survive chilling, avoid freezing, and maintain cell membrane integrity. Simultaneously, CNC- and CNF-formed coatings are porous enough not to block the natural gas exchange essential for plants. CNC trigger internal antioxidant defense systems, upregulating reactive oxygen species-scavenging enzymes and modulating molecular signaling cascades. NC foliar treatment suppresses the growth of pathogenic bacteria and fungi, interferes with their adhesion and plant tissue penetration, and prevents biofilm formation. Thus, topical NC application could be regarded as a multi-functional tool for precision crop management and protection.