Plant Growth Promoting Rhizobacteria and Silica Nanoparticles Stimulate Sugar Beet Resilience to Irrigation with Saline Water in Salt-Affected Soils

Interaction of plants and metal nanoparticles: Exploring its molecular mechanisms for sustainable agriculture and crop improvement

Metal nanoparticles offer promising prospects in agriculture, enhancing plant growth and ensuring food security. Silver, gold, copper, and zinc nanoparticles possess unique properties making them attractive for plant applications. Understanding molecular interactions between metal nanoparticles and plants is crucial for unlocking their potential to boost crop productivity and sustainability. This review explores metal nanoparticles in agriculture, emphasizing the need to understand these interactions. By elucidating mechanisms, it highlights the potential for enhancing crop productivity, stress tolerance, and nutrient-use efficiency, contributing to sustainable agriculture and food security. Quantifying benefits and risks reveal significant advantages. Metal nanoparticles enhance crop productivity by 20% on average and reduce disease incidence by up to 50% when used as antimicrobial agents. They also reduce nutrient leaching by 30% and enhance soil carbon sequestration by 15%, but concerns about toxicity, adverse effects on non-target organisms, and nanoparticle accumulation in the food chain must be addressed. Metal nanoparticles influence cellular processes including sensing, signaling, transcription, translation, and post-translational modifications. They act as signaling molecules, activate stress-responsive genes, enhance defense mechanisms, and improve nutrient uptake. The review explores their catalytic role in nutrient management, disease control, precision agriculture, nano-fertilizers, and nano-remediation. A bibliometric analysis offers insights into the current research landscape, highlighting trends, gaps, and future directions. In conclusion, metal nanoparticles hold potential for revolutionizing agriculture, enhancing productivity, mitigating environmental stressors, and promoting sustainability. Addressing risks and gaps is crucial for their safe integration into agricultural practices.

Synergistic interactions of nanoparticles and plant growth promoting rhizobacteria enhancing soil-plant systems: a multigenerational perspective

Sustainable food security and safety are major concerns on a global scale, especially in developed nations. Adverse agroclimatic conditions affect the largest agricultural-producing areas, which reduces the production of crops. Achieving sustainable food safety is challenging because of several factors, such as soil flooding/waterlogging, ultraviolet (UV) rays, acidic/sodic soil, hazardous ions, low and high temperatures, and nutritional imbalances. Plant growth-promoting rhizobacteria (PGPR) are widely employed in in-vitro conditions because they are widely recognized as a more environmentally and sustainably friendly approach to increasing crop yield in contaminated and fertile soil. Conversely, the use of nanoparticles (NPs) as an amendment in the soil has recently been proposed as an economical way to enhance the texture of the soil and improving agricultural yields. Nowadays, various research experiments have combined or individually applied with the PGPR and NPs for balancing soil elements and crop yield in response to control and adverse situations, with the expectation that both additives might perform well together. According to several research findings, interactive applications significantly increase sustainable crop yields more than PGPR or NPs alone. The present review summarized the functional and mechanistic basis of the interactive role of PGPR and NPs. However, this article focused on the potential of the research direction to realize the possible interaction of PGPR and NPs at a large scale in the upcoming years.

Silicon nanoparticles (SiNPs) stimulated secondary metabolism and mitigated toxicity of salinity stress in basil (Ocimum basilicum) by modulating gene expression: a sustainable approach for crop protection

The underlying mechanisms through which silicon oxide nanoparticles (SiNPs) can confer salinity resistance to plants are poorly understood. This study explored the efficacy of supplementing nutrient solution with SiNPs (20-30 nm; 10 mg kg-1 soil) to stimulate metabolism and alleviate the risks associated with salinity (0.73 g kg-1 soil) in basil seedlings. For this purpose, variations in photosynthetic indices, proline osmoprotectant, antioxidant markers, phenylpropanoid metabolism, and transcriptional behaviors of genes were investigated. SiNPs increased shoot fresh weight (38%) and mitigated the risk associated with the salinity stress by 14%. SiNPs alleviated the inhibitory effects of salinity on the total chlorophyll concentration by 15%. The highest increase (twofold) in proline content was recorded in the SiNP-treated seedlings grown under salinity. The nano-supplement enhanced the activity of enzymatic antioxidants, including peroxidase (2.5-fold) and catalase (4.7-fold). SiNPs induced the expression of gamma-cadinene synthase (CDS) and caffeic acid O-methyltransferase (COMT) genes by 6.5- and 18.3-fold, respectively. SiNPs upregulated the eugenol synthase (EGS1) and fenchol synthase (FES) genes by six- and nine-fold, respectively. Salinity transcriptionally downregulated the geraniol synthase (GES) gene, while this gene displayed an upward trend in response to SiNPs by eight-fold. The nano-supplement transcriptionally stimulated the R-linalool synthase (LIS) gene by 3.3-fold. The terpinolene synthase (TES) gene displayed a similar trend to that of the GES gene. The highest expression (25-fold) of the phenylalanine ammonia-lyase (PAL) gene was recorded in seedlings supplemented with SiNPs. The physiological and molecular assessments demonstrated that employing SiNPs is a sustainable strategy for improving plant primary/secondary metabolism and crop protection.

Salt and drought stress-mitigating approaches in sugar beet (Beta vulgaris L.) to improve its performance and yield

MAIN CONCLUSION

Although sugar beet is a salt- and drought-tolerant crop, high salinity, and water deprivation significantly reduce its yield and growth. Several reports have demonstrated stress tolerance enhancement through stress-mitigating strategies including the exogenous application of osmolytes or metabolites, nanoparticles, seed treatments, breeding salt/drought-tolerant varieties. These approaches would assist in achieving sustainable yields despite global climatic changes. Sugar beet (Beta vulgaris L.) is an economically vital crop for ~ 30% of world sugar production. They also provide essential raw materials for bioethanol, animal fodder, pulp, pectin, and functional food-related industries. Due to fewer irrigation water requirements and shorter regeneration time than sugarcane, beet cultivation is spreading to subtropical climates from temperate climates. However, beet varieties from different geographical locations display different stress tolerance levels. Although sugar beet can endure moderate exposure to various abiotic stresses, including high salinity and drought, prolonged exposure to salt and drought stress causes a significant decrease in crop yield and production. Hence, plant biologists and agronomists have devised several strategies to mitigate the stress-induced damage to sugar beet cultivation. Recently, several studies substantiated that the exogenous application of osmolytes or metabolite substances can help plants overcome injuries induced by salt or drought stress. Furthermore, these compounds likely elicit different physio-biochemical impacts, including improving nutrient/ionic homeostasis, photosynthetic efficiency, strengthening defense response, and water status improvement under various abiotic stress conditions. In the current review, we compiled different stress-mitigating agricultural strategies, prospects, and future experiments that can secure sustainable yields for sugar beets despite high saline or drought conditions.

Composted Bagasse and/or Cyanobacteria-Based Bio-Stimulants Maintain Barley Growth and Productivity under Salinity Stress

Soil and water salinity are among the most fatal environmental challenges that threaten agricultural production worldwide. This study investigated the potential impact(s) of soil amendment using composted bagasse and/or foliar application of cyanobacteria-based bio-stimulants (Arthrospira platensis, also known as Spirulina platensis) to combat the harmful effect(s) of using saline water to irrigate barley plants grown in salt-affected soils during 2020/2021 and 2021/2022. Briefly, the dual application of composted bagasse and cyanobacteria-based bio-stimulants significantly improved the soil properties, buffered the exchangeable sodium percentage (ESP), and enhanced the activity of soil enzymes (urease and dehydrogenase). Moreover, both treatments and their combination notably augmented the water relations of barley plants under salinity stress. All treatments significantly decreased stomatal conductance (gs) and relative water content (RWC) but increased the electrolyte leakage (EL) and balanced the contents of Na⁺ and K⁺, and their ratio (K⁺/Na⁺) of barley leaves under salinity stress compared with those irrigated with fresh water during the 2020/2021 and 2021/2022 seasons. Additionally, composted bagasse and cyanobacteria-based bio-stimulants diminished the oxidative stress in barley plants under salinity stress by improving the activity of antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX). Consequently, the combination of composted bagasse and cyanobacteria extract resulted in superior yield-related traits such as spike length, number of grains per spike, 1000-grain weight, grain yield, straw yield, and harvest index. Collectively, our findings suggest that the integrative application of composted bagasse and cyanobacteria is promising as a sustainable environmental strategiy that can be used to improve soil properties, plant growth, and productivity of not only barley plants but also maybe other cereal crops irrigated with saline water in salt-affected soil.

Synergistic impact of nanomaterials and plant probiotics in agriculture: A tale of two-way strategy for long-term sustainability

Modern agriculture is primarily focused on the massive production of cereals and other food-based crops in a sustainable manner in order to fulfill the food demands of an ever-increasing global population. However, intensive agricultural practices, rampant use of agrochemicals, and other environmental factors result in soil fertility degradation, environmental pollution, disruption of soil biodiversity, pest resistance, and a decline in crop yields. Thus, experts are shifting their focus to other eco-friendly and safer methods of fertilization in order to ensure agricultural sustainability. Indeed, the importance of plant growth-promoting microorganisms, also determined as "plant probiotics (PPs)," has gained widespread recognition, and their usage as biofertilizers is being actively promoted as a means of mitigating the harmful effects of agrochemicals. As bio-elicitors, PPs promote plant growth and colonize soil or plant tissues when administered in soil, seeds, or plant surface and are used as an alternative means to avoid heavy use of agrochemicals. In the past few years, the use of nanotechnology has also brought a revolution in agriculture due to the application of various nanomaterials (NMs) or nano-based fertilizers to increase crop productivity. Given the beneficial properties of PPs and NMs, these two can be used in tandem to maximize benefits. However, the use of combinations of NMs and PPs, or their synergistic use, is in its infancy but has exhibited better crop-modulating effects in terms of improvement in crop productivity, mitigation of environmental stress (drought, salinity, etc.), restoration of soil fertility, and strengthening of the bioeconomy. In addition, a proper assessment of nanomaterials is necessary before their application, and a safer dose of NMs should be applicable without showing any toxic impact on the environment and soil microbial communities. The combo of NMs and PPs can also be encapsulated within a suitable carrier, and this method aids in the controlled and targeted delivery of entrapped components and also increases the shelf life of PPs. However, this review highlights the functional annotation of the combined impact of NMs and PPs on sustainable agricultural production in an eco-friendly manner.