Nano primming: An emerging technology in medicinal and aromatic crops

Introduction

An inventive seed treatment method called nano-priming is quickly becoming known for its potential to completely transform agriculture, particularly when it comes to aromatic and medicinal crops. This method uses nanoparticles (NPs) to improve germination, stress tolerance, and seed quality, among other aspects of plant growth and development. Research indicates that by adjusting plants' physiological and biochemical reactions to external stressors, such as heavy metal toxicity, nano-priming can increase crop yields (Mazhar et al., 2022) [1] . Therefore, using nanoparticles to promote seed germination and overall plant performance, nano-priming is a novel way to boost the growth, development, and stress resilience of aromatic and medicinal crops. Given environmental issues like climate change and resource depletion, this technique has enormous potential to increase the yield and quality of these priceless products. responsible for water uptake, leading to faster and more efficient imbibition, particularly beneficial for aged seeds or seeds with dormancy issues.  Optimized Metabolism: Nano-priming can fine-tune the balance of essential plant hormones like abscisic acid and gibberellins, and regulate levels of reactive oxygen species (ROS) crucial for initiating and regulating metabolic processes that break dormancy and promote germination.  Improved Seedling Vigour: Faster germination and more robust initial growth translate into stronger, healthier seedlings that can establish themselves more effectively in the field, increasing their chances of survival and maximizing yield.

Enhancing plant growth and secondary metabolite production

 Improved Nutrient Acquisition: Nano-priming with specific nanoparticles (e.g., zinc, iron) can enhance the uptake and utilization of essential nutrients by roots, leading to better plant growth and development.  Increased Photosynthesis: Some nanoparticles can boost chlorophyll synthesis and photosynthetic efficiency, leading to increased biomass production, according to ScienceDirect.com.  Modulated Metabolism: Nano-priming can influence gene expression related to metabolic processes, including the production of valuable secondary metabolites (e.g., flavonoids, anthocyanins, glucosinolates) in medicinal and aromatic plants, potentially boosting the content and efficacy of their active compounds. [1] .

Enhancing stress resilience  Abiotic Stress

Notwithstanding these difficulties, nano-priming has the potential to completely transform the production of aromatic and medicinal crops by giving them the means to flourish in progressively harsher conditions, ultimately promoting sustainable agriculture and satisfying the world's need for food and medicine. Wider use and long-term advantages of this cutting-edge technology will be made possible by additional research concentrating on comprehending the molecular mechanisms at play, investigating novel nanoparticle forms, and resolving safety concerns (Elbanna et al., 2024) [2] . [3] examined the combined impacts of TiO2NPs and seed priming, which resulted in improved seedling growth and stress resistance. Likewise, Iqbal et al.

(2022) [4] investigated the physiological impacts of gammaaminobutyric acid (GABA) therapy on drought-stricken sweet pepper, demonstrating enhanced growth and stress tolerance. Furthermore, research by Sardar et al. (2023) and Kandileri et al. (2021) [5,6] evaluated the impact of several treatments on early-stage seedling growth and seed germination in species such as Saraca asoca and Swertia chirata, showing notable increases in physiological parameters. Furthermore, studies on the use of ZnONPs (Ajmal et al., 2023) [7] , iron oxide nanoparticles (Mazhar et al., 2022) [1] , and selenium priming (Sariñana-Navarrete et al., 2024) [8] to different crops highlight the potential of these nanomaterials in agricultural enhancement. In addition to analyzing the possible uses and ramifications of nanotechnology in contemporary agriculture, this study attempts to provide a thorough examination of these investigations, including an outline of the methodology employed and their findings.

Materials and Methods

In order to assess the effects of copper nanoparticles (CuNPs) and Spirulina sp. on growth metrics like leaf area, biomass, and essential oil content, Elbanna et al. (2024) [2] treated French basil plants during the vegetative stage with foliar treatments of both Spirulina sp. and CuNPs, both separately and in combination. The results showed that the combination of CuNPs and Spirulina significantly enhanced plant growth, as seen by a discernible increase in leaf area, biomass, and essential oil content when compared to the control group. Although separate therapy also produced positive outcomes, the combination treatment proved to be the most effective. The observed synergistic effect was attributed to the antioxidant properties of spirulina and the enhanced nutritional absorption of CuNPs, suggesting that this approach could be helpful for promoting the growth of medicinal plants, particularly in controlled environments.

Results and discussion

The produced CuNPs were found to be spherical with a mean diameter of 4.51 nm by TEM analysis (Fig. 1), and their crystalline structure was confirmed by XRD analysis (Fig. 2), which revealed a face-centered cubic phase of copper. The fresh and dry weight of basil was greatly increased by applying 500 mg/L CuNPs; the greatest values were noted at this concentration (Table 1), however growth was inhibited by higher doses. Compared to CuNPs alone, the combination of CuNPs (500 mg/L) and Spirulina extract (1.5 g/L) produced the best growth performance in both seasons. This supports earlier research showing that the combination of biofertilizers and nanofertilizers increases plant growth and the generation of essential oils. Table 2 and Table 3 summarize the plant height, number of branches, oil yield, and oil percentage, with significant improvements observed in treatments combining CuNPs and Spirulina, especially at 500 mg/L CuNPs and 1.5 g/L Spirulina. [3] examined the effects of using green-synthesized titanium dioxide nanoparticles (TiO2NPs) for pomegranate seed priming on plant vigor, seed germination, and seedling growth in both controlled and field settings. TiO2NP-primed seeds showed better germination rates, increased seedling development, and overall vigor as compared to untreated seeds. The nanoparticles also improved nutrient absorption from the soil. By optimizing nutrient uptake and promoting earlystage growth, the study highlighted the potential of TiO NPs in seed priming, particularly in suboptimal soil conditions. This suggests that their inclusion in seed priming protocols could significantly improve the growth and agronomic profile of pomegranate plants.

Locally produced coffee beans, pomegranate fruits, and titanium dioxide (TiO2) from Across Organics were among the items used in this investigation. Plant extracts made from coffee grounds and pomegranate peels were combined with an aqueous TiO2 solution and heated to biosynthesize TiO2 nanoparticles (TiO2NPs). The TiO2NPs were subsequently examined for seed priming, uptake, and internalization after being described using a variety of methods, such as UV-Vi spectroscopy, TEM, SEM, XRD, and EDX.

Results and Discussion

Changes in colour and UV-Vis spectra (Figure 3) verified the creation of titanium dioxide nanoparticles (TiO2NPs) using coffee extract (CE) and pomegranate peel extract (PPE). Random clusters of irregularly shaped nanoparticles were found by SEM analysis (Figure 3A). TiO2NP uptake in seed embryos was verified by TEM and XRF studies, with TiO2NPs_CE exhibiting greater accumulation (Figure 4 and5).

Fig 2:

Green synthesis of titanium dioxide nanoparticles using pomegranate peel extract (PPE), and coffee ground extract (CE).

(A):

Change in colour of the reaction to cloudy yellow and brown after -the production of nanoparticles. [4] evaluated the impact of gammaaminobutyric acid (GABA) on photosynthetic activity, water consumption efficiency, and antioxidant enzyme activities. The researchers treated drought-stressed sweet pepper plants by preparing the soil and sprinkling GABA on the leaves. The results showed that, particularly in drought conditions, GABA treatment significantly raised photosynthetic activity, water use efficiency, and antioxidant enzyme levels as compared to the control group.

Better growth and higher yields were the outcome of this.

The results of the study show that GABA is a helpful biostimulant that increases plant tolerance, maintains cellular homeostasis, and encourages growth and yield in water-limited conditions, all of which assist sweet peppers resist drought stress. Materials and methods Two Capsicum annuum L. types, Mercury and Scope F1, were used in field trials at Qurtuba University in Peshawar, Pakistan. The plants were planted in clay containers with a 3:1 sand-loam soil mixture and composted manure. To evaluate the physiological response, plants were exposed to three different levels of water stress (control, moderate, and severe) and treated with different concentrations of GABA (0, 2, and 4 mM). Samples were taken for examination at 80% maturity. Numerous agronomic, biochemical, and physiological characteristics, such as photosynthetic pigments, soluble sugars, and antioxidant enzyme activities, were examined in soil and plant samples.

Results and Discussion

The development and physiological characteristics of Capsicum annuum L., such as root and shoot characteristics, chlorophyll content, and antioxidant activity, were markedly improved by the application of GABA foliar spray during drought stress (Fig 6A -6c). Under 50% field capacity drought stress, 2 mM GABA was the most effective concentration, whereas under 30% drought stress, 4 mM GABA worked better. Additionally, the study found a strong favorable link between proline, soluble sugars, antioxidant enzymes, and chlorophyll concentration (Table 4, Table 5). These results show that GABA can improve the physiological responses and biochemical contents of plants, there by mitigating drought stress.

Material and Methods

15 pre-sowing treatments and a control were used in the experimental investigation, which was carried out in the central forest nursery greenhouse at Uttar Banga Krishi Vishwavidyalaya in West Bengal, India, between May 2018 and May 2020. It was reproduced three times using a randomized block design. To evaluate their effects on seed germination and seedling growth, the seeds were subjected to mechanical treatments such as rubbing with sandpaper, as well as soaking in different concentrations of salicylic acid, thiourea, and hot or regular water. With data collected at intervals up to a year, the study examined the seedling Vigor index, shoot and root lengths, and other growth metrics.

Results and Discussion

The study showed that the best methods for improving Sarasa asoca germination, seedling vigor, and growth characteristics were mechanical treatment (T5), hot water treatment (T6), and chemical treatments with thiourea (T13-T15). By promoting moisture and air penetration, these treatments enhanced germination by softening seed coatings and promoting embryo growth (Table 4). However, because of oxygen deprivation and embryo damage, prolonged soaking times in water-especially at higher temperaturesled to decreased germination. The best results were obtained with 200 ppm of thiourea (T14) and 120 ppm of salicylic acid (T2), which increased seedling development by encouraging meristematic activity and nutrient uptake.

References

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