Explore the vast range of titles available.

Abiotic stresses lead to excessive crop yield losses and are a major threat to agriculture. It is essential to equip crops with multi-stress tolerance to mitigate the adverse effects of abiotic stressors and meet the demands of the increasing global population. The association between plants and symbiotic microorganisms is involved in key functions at the ecosystem and plant levels, and the application of microbial plant biostimulants (MPBs) is a sustainable strategy to augment plant growth and productivity, even under abiotic stress conditions. Several different microorganisms can be used as MPBs to enhance plant growth and produce progressive and reproducible effects on crops. In the present review, we assessed the current knowledge on the use of MPBs, discuss the diversity and characteristics of MPBs, and provide a meticulous assessment of the possible applications of MPBs in abiotic stress relief in crops.

Seaweed-based biostimulants (SBB) have emerged as sustainable alternatives for traditional soil-based agriculture and have garnered worldwide attention in recent years. Despite their growing popularity, there is limited information available on the application and efficacy of SBB in hydroponic crops. This study assesses the biostimulant effects of a commercial SBB using Lemna minor as a model organism, developing a standardized bioassay for evaluating SBB in hydroponic cultures. The experiment was carried out under controlled conditions, following a randomized design with 10 treatments. These treatments included SBB (0T1, 0.5T1, 2T1) alone at concentrations of 0, 0.5, and 2.0 mg/L, SBB (0T2, 0.5T2, 2T2) + Hoagland and Arnon nutrient solution, and SBB (0T30, 0.5T3, 2T3) + 2.5 g/L NaCl. A control group (0TC) with distilled water was also included. The results showed that the isolated SBB did not significantly differ (p > 0.05) from the control treatment. Treatments in group T2 had significantly higher coverage area compared to treatments in group T3. The highest absolute percentage of coverage area was observed in 0.5T2 (14.0 ± 1.2%). Regarding the specific growth rate SGR, the higher growth rates were observed in 0.5T2 (0.37 ± 0.02% day⁻1). Group T2 treatments exhibited significantly higher dry biomass (p < 0.05) than group T3 treatments. Treatment with NaCl hindered plant growth. This methodology could enhance the development of a robust protocol for evaluating seaweed biostimulants for hydroponic crops. Keywords: biostimulants, duckweed, seaweed extract.

Microbial plant biostimulants have been successfully applied to improve plant growth, stress resilience and productivity. However, the mechanisms of action of biostimulants are still enigmatic, which is the main bottleneck for the fully realization and implementation of biostimulants into the agricultural industry. Here, we report the elucidation of a global metabolic landscape of maize ( Zea mays L) leaves in response to a microbial biostimulant, under well-watered and drought conditions. The study reveals that the increased pool of tricarboxylic acid (TCA) intermediates, alterations in amino acid levels and differential changes in phenolics and lipids are key metabolic signatures induced by the application of the microbial-based biostimulant. These reconfigurations of metabolism gravitate toward growth-promotion and defense preconditioning of the plant. Furthermore, the application of microbial biostimulant conferred enhanced drought resilience to maize plants via altering key metabolic pathways involved in drought resistance mechanisms such as the redox homeostasis, strengthening of the plant cell wall, osmoregulation, energy production and membrane remodeling. For the first time, we show key molecular events, metabolic reprogramming, activated by a microbial biostimulant for plant growth promotion and defense priming. Thus, these elucidated metabolomic insights contribute to ongoing efforts in decoding modes of action of biostimulants and generating fundamental scientific knowledgebase that is necessary for the development of the plant biostimulants industry, for sustainable food security.

The rapidly growing industry of crop biostimulants leverages the application of plant growth promoting rhizobacteria (PGPR) to promote plant growth and health. However, introducing nonnative rhizobacteria may impact other aspects of ecosystem functioning and have legacy effects; these potential consequences are largely unexplored. Nontarget consequences of PGPR may include changes in resident microbiomes, nutrient cycling, pollinator services, functioning of other herbivores, disease suppression, and organic matter persistence. Importantly, we lack knowledge of whether these ecosystem effects may manifest in adjacent ecosystems. The introduced PGPR can leave a functional legacy whether they persist in the community or not. Legacy effects include shifts in resident microbiomes and their temporal dynamics, horizontal transfer of genes from the PGPR to resident taxa, and changes in resident functional groups and interaction networks. Ecosystem functions may be affected by legacies PGPR leave following niche construction, such as when PGPR alter soil pH that in turn alters biogeochemical cycling rates. Here, we highlight new research directions to elucidate how introduced PGPR impact resident microbiomes and ecosystem functions and their capacity for legacy effects.

Crop production systems have adopted cost-effective, sustainable and environmentally friendly agricultural practices to improve crop yields and the quality of food derived from plants. Approaches such as genetic selection and the creation of varieties displaying favorable traits such as disease and drought resistance have been used in the past and continue to be used. However, the use of biostimulants to promote plant growth has increasingly gained attention, and the market size for biostimulants is estimated to reach USD 4.14 billion by 2025. Plant biostimulants are products obtained from different inorganic or organic substances and microorganisms that can improve plant growth and productivity and abate the negative effects of abiotic stresses. They include materials such as protein hydrolysates, amino acids, humic substances, seaweed extracts and food or industrial waste-derived compounds. Fish processing waste products have potential applications as plant biostimulants. This review gives an overview of plant biostimulants with a focus on fish protein hydrolysates and legislation governing the use of plant biostimulants in agriculture.

The market for seaweed extract biostimulants is experiencing rapid growth, driven by increasing awareness of their benefits and the need for sustainable agricultural practices. This opinion article reviews recent developments in the commercialization of seaweed extract biostimulants, including data on market value and geographical spread, and highlighting the emergence of new species in use. The author advances that recent market trends indicate the start of a gradual transition from wild-harvested to cultivated seaweed sources for biostimulants, while the current proliferation of products is setting the stage for future consolidation of the sector. Challenges to improve market uptake and strategies for companies looking to achieve primacy in the market are discussed.

IntroductionDrought stress severely constrains global crop production, limiting growth, yield, and fruit quality. This study evaluated the efficacy of foliar-applied melatonin (MT) in enhancing drought tolerance in tomato (Solanum lycopersicum L.) by modulating physiological and biochemical responses.MethodsA two-season field experiment employed a split-plot design with three replications, testing two irrigation regimes [full irrigation (FI; 100% crop evapotranspiration, ETc) and deficit irrigation (DI; 60% ETc)], combined with five foliar MT concentrations (0, 50, 100, 150, and 200 µM) applied as foliar sprays.ResultsDI alone significantly (P ≤ 0.05) reduced plant height (26.9%), total yield (44.0%), soil plant analysis development (SPAD) chlorophyll value (41.7%), and relative water content (RWC; 28.6%) compared to well-watered controls. Exogenous MT at 100 µM significantly (P ≤ 0.05) alleviated these effects under DI, increasing plant height by 32.9%, total yield by 51.8%, SPAD value by 51.1%, and RWC by 31.0% relative to untreated stressed plants. MT application enhanced photosynthetic efficiency and preserved leaf integrity, reflected in reduced electrolyte leakage and malondialdehyde content. These improvements stemmed from effective reactive oxygen species (H2O2 and O2•–) detoxification, accompanied by a significant (P ≤ 0.05) upregulation of enzymatic antioxidants [superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), catalase (CAT), and glutathione reductase (GR)] and accumulation of non-enzymatic osmoprotectants including proline, ascorbate, α-tocopherol, glutathione, and total soluble sugars. The FI + 100 μM MT treatment yielded the highest fruit production (5.31 kg plant-1).DiscussionThese findings establish foliar MT application at 100 μM as an effective biostimulant strategy for sustaining tomato productivity under water-limited conditions, operating through coordinated key physiological and biochemical defense mechanisms. This approach offers a practical pathway toward more resilient crop production in water-scarce environments.

Modern agriculture is being challenged by deteriorating edaphoclimatic conditions and increasing anthropogenic pressure. This necessitates the development of innovative crop production systems that can sustainably meet the demands of a growing world population while minimizing the environmental impact. The use of plant biostimulants is gaining ground as a safe and ecologically sound approach to improving crop yields. In this review, biostimulants obtained from different higher plant sources are presented under the term higher plant-derived biostimulants (hPDBs). Their mechanisms of action regulate physiological processes in plants from germination to fructification, conditioned by responses induced in plant mineral nutrition and primary metabolism, specialized metabolism, photosynthetic processes, oxidative metabolism, and signaling-related processes. The aim of this review is to collect and unify the abundant information dispersed in the literature on the effects of these biostimulants, focusing on crops subjected to abiotic stress conditions and the underlying mechanisms of action.