Agriculture needs to decrease the use of agrochemicals due to their high toxicity and adopt new strategies to achieve sustainable food production. Therefore, nanoparticles (NPs) and plant growth-promoting bacteria (PGPB) have been proposed as viable strategies to obtain better crop yields with less environmental impact. Here, we describe the effect of silica nanoparticles (SiO₂-NPs) on survival, antioxidant enzymatic activity, phosphate solubilization capacity, and gibberellin production of Bacillus cereus-Amazcala (B.c-A). Moreover, the effect of the co-application of SiO₂-NPs and B.c-A on seed germination, physiological characteristics, and antioxidant enzymatic activity of chili pepper plants was investigated under greenhouse conditions. The results indicated that SiO₂-NPs at 100 ppm enhanced the role of B.c-A as PGPB by increasing its phosphate solubilization capacity and the production of GA7. Moreover, B.c-A catalase (CAT) and superoxide dismutase (SOD) activities were increased with SiO₂-NPs 100 ppm treatment, indicating that SiO₂-NPs act as a eustressor, inducing defense-related responses. The co-application of SiO₂-NPs 100 ppm and B.c-A improved chili pepper growth. There was an increase in seed germination percentage, plant height, number of leaves, and number and yield of fruits. There was also an increase in CAT and PAL activities in chili pepper plants, indicating that bacteria–NP treatment induces plant immunity.

Agricultural systems face several challenges in terms of meeting everyday-growing quantities and qualities of food requirements. However, the ecological and social trade-offs for increasing agricultural production are high, therefore, more sustainable agricultural practices are desired. Researchers are currently working on diverse sustainable techniques based mostly on natural mechanisms that plants have developed along with their evolution. Here, we discuss the potential agricultural application of extracellular DNA (eDNA), its multiple functioning mechanisms in plant metabolism, the importance of hormetic curves establishment, and as a challenge: the technical limitations of the industrial scale for this technology. We highlight the more viable natural mechanisms in which eDNA affects plant metabolism, acting as a damage/microbe-associated molecular pattern (DAMP, MAMP) or as a general plant biostimulant. Finally, we suggest a whole sustainable system, where DNA is extracted from organic sources by a simple methodology to fulfill the molecular characteristics needed to be applied in crop production systems, allowing the reduction in, or perhaps the total removal of, chemical pesticides, fertilizers, and insecticides application.

Agriculture depends on fertilizers to provide nutrients for plants. Phosphorus (P) is one of these nutrients and is the second-most necessary for plant growth. Global production of P fertilizer is concentrated in Morocco, China and the United States. A large amounts of P resources are found in organic wastes that can be transformed through phosphate-solubilizing microorganisms during the composting process. In this study, we first determined the enzymatic activity of phosphatases and phytase from Pseudomonas aeruginosa ATC 15442. Second, we evaluated the mineralization of P in mature compost when inoculated with P. aeruginosa ATC 15442, phytases, a cocktail of phosphate-solubilizing enzymes and their combinations. Finally, we evaluated different concentrations of the cocktail trying to release more P in the compost. The results indicated that P. aeruginosa exuded alkaline phosphatases, acid phosphatase, neutral phosphatase and phytase. The enzymatic cocktail increased inorganic P (Pi) when added to the mature compost: this was able to release up to 95% more Pi in the compost compared to the amount of Pi released in the control compost. The current study demonstrated the importance of adding the cocktail to enhance Pi in mature compost; however, further studies are required to confirm the results and practical applications.

La agricultura es la base de la alimentación, se desarrolla en suelo e hidroponía. La hidroponía se explica cómo cultivos sin suelo, en soluciones nutritivas, para el caso del tomate y del pepino es en sustrato. Los sustratos han incrementado la productividad, con uso eficiente de agua y fertilizantes. Si la agricultura consume 70% de agua y en gasto 30% es fertilizantes, el objetivo de este trabajo fue utilizar hidrogel de acrilato de potasio por su capacidad de disminuir la pérdida de fertilizantes como ser reserva de agua, permitiendo mantener la producción de tomate y pepino. La investigación se realizó en Querétaro en 2017. Se evaluó diferentes capacidades de saturación del hidrogel para sus propiedades, la mezcla de sustrato y el rendimiento de tomate y pepino, encontrando diferencias significativas.

Elicitor application to plants has been used to induce them to produce secondary metabolites. Depending on elicitor dosing plants may present eustress or distress. In this study we presented a first approach to study the effect of elicitors on photosynthesis of tomato plants and used it as an indicator of stress. Salicylic acid and hydrogen peroxide were used in three doses via foliar and radicular pathways. Photosynthesis was evaluated using a chamber where a whole plant was enclosed, and CO2 consumption was measured over time. CO2 consumption curves showed a linear behavior, changes in the slope indicated low or high photosynthetic plant activity. Photosynthesis may be used as a plant stress indicator in precision agriculture.

The overreliance on non-renewable phosphate fertilizers necessitates sustainable alternatives for phosphorus recycling in agriculture. This study aimed to characterize and enhance the metabolic activity of phosphate-solubilizing microorganisms isolated from compost by eliciting them with two distinct mesoporous silica nanoparticles: standard SBA-15-S and short-pore SBA-15-C. Bacterial strains with broad-spectrum P solubilization and mineralization capacities were isolated from the mesophilic phases of tomato greenhouse and cow manure composts. These isolates received treatment with nanoparticle concentrations of 0.1, 10, and 100 ppm. The results demonstrated that nanoparticle elicitation significantly altered microbial growth, solubilization halos on tricalcium phosphate, and the specific activity of acid, neutral, and alkaline phosphatases in a strain- and nanoparticle-dependent manner. Notably, SBA-15-C at 100 ppm consistently enhanced multiple P-recycling properties across several strains, including Proteus and Myroides species. Principal component analysis revealed distinct behavioral clusters between composting phases and isolation methods. The findings indicate that tailored silicon oxide nanostructures can serve as eustressors to modulate and enhance the P-solubilizing and mineralizing functions of compost-derived microbiota, offering a promising nanobiostimulation strategy for developing enhanced biofertilizers.