Effects of Soil pH and Coatings on the Efficacy of Polymer coated ZnO Nanoparticulate fertilizers in Wheat (Triticum aestivum)

Effects of particle size on toxicity, bioaccumulation, and translocation of zinc oxide nanoparticles to bok choy (Brassica chinensis L.) in garden soil

The indiscriminate use of zinc oxide nanoparticles (ZnO NPs) in daily life can lead to their release into soil environment. These ZnO NPs can be taken up by crops and translocated to their edible part, potentially causing risks to the ecosystem and human health. In this study, we conducted pot experiments to determine phytotoxicity, bioaccumulation and translocation depending on the size (10 - 30 nm, 80 - 200 nm and 300 nm diameter) and concentration (0, 100, 500 and 1000 mg Zn/kg) of ZnO NPs and Zn ion (Zn2+) in bok choy, a leafy green vegetable crop. After 14 days of exposure, our results showed that large-sized ZnO NPs (i.e., 300 nm) at the highest concentration exhibited greater phytotoxicity, including obstruction of leaf and root weight (42.5 % and 33.8 %, respectively) and reduction of chlorophyll a and b content (50.2 % and 85.2 %, respectively), as well as changes in the activities of oxidative stress responses compared to those of small-sized ZnO NPs, although their translocation ability was relatively lower than that of smaller ones. The translocation factor (TF) values decreased as the size of ZnO NPs increased, with TF values of 0.68 for 10 - 30 nm, 0.55 for 80 - 200 nm, and 0.27 for 300 nm ZnO NPs, all at the highest exposure concentration. Both the results of micro X-ray fluorescence (μ-XRF) spectrometer and bio-transmission electron microscopy (bio-TEM) showed that the Zn elements were mainly localized at the edges of leaves exposed to small-sized ZnO NPs. However, the Zn elements upon exposure to large-sized ZnO NP were primarily observed in the primary veins of leaves in the μ-XRF data, indicating a limitation in their ability to translocate from roots to leaves. This study not only advances our comprehension of the environmental impact of nanotechnology but also holds considerable implications for the future of sustainable agriculture and food safety.

Nano-enabled strategies to promote safe crop production in heavy metal(loid)-contaminated soil

Nanobiotechnology is a potentially safe and sustainable strategy for both agricultural production and soil remediation, yet the potential of nanomaterials (NMs) application to remediate heavy metal(loid)-contaminated soils is still unclear. A meta-analysis with approximately 6000 observations was conducted to quantify the effects of NMs on safe crop production in soils contaminated with heavy metal(loid) (HM), and a machine learning approach was used to identify the major contributing features. Applying NMs can elevate the crop shoot (18.2 %, 15.4-21.2 %) and grain biomass (30.7 %, 26.9-34.9 %), and decrease the shoot and grain HM concentration by 31.8 % (28.9-34.5 %) and 46.8 % (43.7-49.8 %), respectively. Iron-NMs showed a greater potential to inhibit crop HM uptake compared to other types of NMs. Our result further demonstrates that NMs application substantially reduces the potential health risk of HM in crop grains by human health risk assessment. The NMs-induced reduction in HM accumulation was associated with decreasing HM bioavailability, as well as increased soil pH and organic matter. A random forest model demonstrates that soil pH and total HM concentration are the two significant features affecting shoot HM accumulation. This analysis of the literature highlights the significant potential of NMs application in promoting safe agricultural production in HM-contaminated agricultural lands.

Nanotechnology in Agriculture: Manganese Ferrite Nanoparticles as a Micronutrient Fertilizer for Wheat

Limited research has focused on nanoparticle (NP) applications' impact on edible wheat parts in a field environment. Here, we studied the nutritional quality of edible parts of wheat (Triticum aestivum L.) with a field experiment by spraying MnFe2O4 nanoparticles. Wheat was foliar sprayed with 0, 25, 50, and 100 mg/L composite manganese ferrite (MnFe2O4) NPs during 220 d of a growth period. Ionic controls were prepared using the conventional counterparts (MnSO4·H2O and FeSO4·7H2O) to compare with the 100 mg/L MnFe2O4 NPs. After three consecutive foliar applications, nanoparticles demonstrated a substantial elevation in grain yield and harvest index, exhibiting a noteworthy increase to 5.0 ± 0.12 t/ha and 0.46 ± 0.001 in the 100 mg/L NP dose, respectively, concomitant with a 14% enhancement in the grain number per spike. Fe, Mn, and Ca content in grain increased to 77 ± 2.7 mg/kg, 119 ± 2.8 mg/kg, and 0.32 ± 7.9 g/kg in the 100 mg/L NPs, respectively. Compared to the ion treatment, the 100 mg/L NP treatments notably boosts wheat grain crude protein content (from 13 ± 0.79% to 15 ± 0.58%) and effectively lowers PA/Fe levels (from 11 ± 0.7 to 9.3 ± 0.5), thereby improving Fe bioavailability. The VSM results exhibited a slight superparamagnetic behavior, whereas the grains and stems exhibited diamagnetic behavior. The results indicate that the nanomaterial did not accumulate in the grains, suggesting its suitability as an Fe and Mn-rich fertilizer in agriculture. Above all, the foliar application of nanocomposites increased the concentrations of Fe, Mn, and Ca in wheat grains, accompanied by a significant enhancement in grain yield. Therefore, the research results indicate that the foliar application of MnFe2O4 NPs can positively regulate wheat grains' nutritional quality and yield.

Fulvic acid modified ZnO nanoparticles improve nanoparticle stability, mung bean growth, grain zinc content, and soil biodiversity

Zinc oxide nanoparticles (ZnO NPs) have emerged as a novel solution to combat Zn deficiency in agriculture. However, challenges persist regarding their Zn utilization efficiency and environmental impact. Fulvic acid (FA), as a relatively mature modified material, is a promising candidate to enhance the environmental stability of ZnO NPs. This study investigates modifying ZnO NPs with FA to improve their stability and increase Zn content in mung bean fruit and explores their effect on plants and the soil ecosystem. We combined FA and ZnO NPs (FZ-50) at mass ratios of 1: 5, 1: 2, and 4: 5, denoted as 20 % FZ, 50 % FZ, and 80 % FZ, respectively. Initial germination tests revealed that the 50 % FZ treatment improved sprout growth and Zn content and minimized agglomeration the most. A subsequent pot experiment compared FZ-50 with ZnO, ZnO NPs, and F + Z (1: 1 FA: ZnO NPs). Notably, the FZ-50 treatment (50 % FZ applied to the soil) demonstrated superior results, exhibiting a 30.25 % increase in yield, 121 % improvement in root nodule quality, and 56.38 % increase in Zn content, with no significant changes in enzyme activities (catalase and peroxidase). Furthermore, FZ-50 increased soil available Zn content and promoted soil microorganism diversity, outperforming ZnO and ZnO NPs. This study underscores the potential of FA as a relatively mature material for modifying ZnO NPs to increase grain Zn content, presenting a novel approach to addressing Zn deficiency in agriculture.

Nano-enabled seed treatment: A new and sustainable approach to engineering climate-resilient crops

Under a changing climate, keeping the food supply steady for an ever-increasing population will require crop plants adapted to environmental fluctuations. Genetic engineering and genome-editing approaches have been used for developing climate-resilient crops. However, genetically modified crops have yet to be widely accepted, especially for small-scale farmers in low-income countries and some societies. Nano-priming (seed exposure to nanoparticles, NPs) has appeared as an alternative to the abovementioned techniques. This technique improves seed germination speed, promotes seedlings' vigor, and enhances plant tolerance to adverse conditions such as drought, salinity, temperature, and flooding, which may occur under extreme weather conditions. Moreover, nano-enabled seed treatment can increase the disease resistance of crops by boosting immunity, which will reduce the use of pesticides. This unsophisticated, farmer-available, cost-effective, and environment-friendly seed treatment approach may help crop plants fight climate change challenges. This review discusses the previous information about nano-enabled seed treatment for enhancing plant tolerance to abiotic stresses and increasing disease resistance. Current knowledge about the mechanisms underlying nanomaterial-seed interactions is discussed. To conclude, the review includes research questions to address before this technique reaches its full potential.

Zinc oxide nanoparticles enhanced rice yield, quality, and zinc content of edible grain fraction synergistically

Zinc oxide nanoparticles (ZnO NPs) have been widely used in agriculture as a new type of Zn fertilizer, and many studies were conducted to evaluate the effect of ZnO NPs on plant growth. However, there are relatively few studies on the effects of application methods and appropriate dosages of ZnO NPs on rice yield, quality, grain Zn content, and distribution. Therefore, in the 2019 and 2020, field trials were conducted with six ZnO NPs basal application dosages of no ZnO NPs, 3.75 kg hm-2, 7.5 kg hm-2, 15 kg hm-2, 30 kg hm-2, and 60 kg hm-2, and the effects of ZnO NPs application on rice yield, quality, grain Zn content, and distribution were investigated. The results demonstrated that applying ZnO NPs in Zn-deficient soils (available Zn < 1.0 mg kg-1) increased rice grain yield by 3.24%-4.86% and 3.51%-5.12% in 2019 and 2020, respectively. In addition, ZnO NPs improved the quality of rice by increasing the head milling rate, reducing chalky grain percentage, and increasing the taste value and breakdown of rice. In terms of Zn accumulation in rice, ZnO NPs application significantly increased the Zn content in both milled rice and brown rice, compared with no Zn treatment, in 2019 and 2020, Zn content in milled rice significantly increased by 20.46%-41.09% and 18.11%-38.84%, respectively, and in brown rice significantly increased by 25.78%-48.30% and 20.86%-42.00%, respectively. However, the Zn fertilizer utilization gradually decreased with increasing ZnO NPs application dosage. From the perspective of yield, rice quality, Zn fertilizer utilization, and Zn accumulation, basal application of 7.5 kg-30 kg hm-2 ZnO NPs is beneficial for rice yield and quality improvement and rice Zn accumulation. This study effectively demonstrated that ZnO NPs could be a potential high-performed fertilizer for enhancing rice yield, quality, and zinc content of edible grain fraction synergistically.

Transformation of zinc oxide nanoparticles in the presence of aluminum oxide with pre-sorbed phosphorus ligands

Naturally occurring oxides could react with zinc oxide (ZnO) nanoparticles (NPs) and then change its transformation and toxicity to ecological receptors. The reaction may be affected by a variety of environmental factors, yet the relevant processes and mechanisms are limitedly investigated. Natural prevalent ligands, as an important factor, can sorb on natural oxide minerals and change its surface property, finally affecting ZnO NP transformation. This study investigated the interactions of ZnO NPs with phosphorus ligands (i.e., phytate and orthophosphate) pre-sorbed γ-alumina (γ-Al₂O₃) via batch experiments and multi-technique analyses. A limited amount of aqueous Zn²⁺ is observed when the concentration of ZnO NPs is relatively low (<64.8 mg L^-1) in the presence of phytate pre-sorbed γ-Al₂O₃. Solid Zn(II) species includes binary/ternary surface Zn(II) complexes on γ-Al₂O₃ with minor amounts of zinc phytate precipitates. As the concentration of ZnO NPs increases, surface Zn(II) complexes gradually transform into zinc phytate and Zn-Al layered double hydroxide (Zn-Al LDH) precipitates. The quantitative analysis indicates that, as the concentration of ZnO NPs increases from 32.4 to 388.8 mg L^-1, the proportion of Zn(II) species as binary/ternary surface complexes decreases from 81.9 to 30.2%; and the proportion as zinc phytate and Zn-Al LDH increases from 17.9 to 27.6% and 0 to 43.8%, respectively. The pre-sorption of orthophosphate can also inhibit ZnO NP transformation into Zn-Al LDH precipitates on γ-Al₂O₃. This study suggests that natural ligands pre-existed on natural oxide minerals could greatly influence the solubility, stability, transformation, and fate of easily dissoluble metal oxides (e.g., ZnO) in the environments.

Particelle nanostrutturate di idrossiapatite biomimetica come sistema di delivery di micro e macro elementi nelle colture biologiche

Nanoparticelle biomimetiche di idrossiapatite drogate con ioni metallici (Cu, Fe, Mg, Zn, K) sono state utilizzate in formulazioni contenenti basse concentrazioni di rame (Cu) e zolfo (S) per controllare la peronospora (plasmopara viticola) e l'oidio (erysiphe necator) della vite. I formulati sono stati testati in campo sulla varietà di vino "Dolcetto" coltivata secondo tecniche di agricoltura biologica, e la loro efficacia è stata confrontata con prodotti commerciali contenenti miscela bordolese e zolfo.

I dati indicano che le formulazioni contenenti bassi dosaggi di rame e zolfo possono essere trasportati in modo efficiente dalle nanoparticelle di idrossiapatite biomimetica e possono ridurre la presenza di micota sulle foglie della vite. Nessun residuo di rame e zolfo è stato rilevato in campioni di vino ottenuti da viti in cui è stata utilizzata l'idrossiapatite biomimetica. Il drogaggio di nanoparticelle di idrossiapatite biomimetica con metalli di transizione è un modo efficiente per fornire micro e macro-elementi alle piante a basso livello di dosaggio. Le formulazioni contenenti idrossiapatite funzionano anche come supporti a lento rilascio di macronutrienti come elementi di calcio e fosforo.

Nanobiotechnology-based strategies for enhanced crop stress resilience

Nanobiotechnology approaches to engineering crops with enhanced stress tolerance may be a safe and sustainable strategy to increase crop yield. Under stress conditions, cellular redox homeostasis is disturbed, resulting in the over-accumulation of reactive oxygen species (ROS) that damage biomolecules (lipids, proteins and DNA) and inhibit crop growth and yield. Delivering ROS-scavenging nanomaterials to plants has been shown to alleviate abiotic stress. Here we review the current state of knowledge of using ROS-scavenging nanomaterials to enhance plant stress tolerance. When present below a threshold level, ROS can mediate redox signalling and defence pathways that foster plant acclimatization against stress. We find that ROS-triggering nanomaterials, such as nanoparticulate silver and copper oxide, have the potential to be judiciously applied to crop species to stimulate the defence system, prime stress responses and subsequently increase the stress resistance of crops.

Engineered Zn-based nano-pesticides as an opportunity for treatment of phytopathogens in agriculture

People's desire for food has never slowed, despite the deterioration of the global agricultural environment and the threat to food security. People rely on agrochemicals to ensure normal crop growth and to relieve the existing demand pressure. Phytopathogens have acquired resistance to traditional pesticides as a result of pesticdes' abuse. Compared with traditional formulations, nano-pesticides have superior antimicrobial performance and are environmentally friendly. Zn-based nanoparticles (NPs) have shown their potential as strong antipathogen activity. However, their full potential has not been demonstrated yet. Here, we analyzed the prerequisites for the use of Zn-based NPs as nano-pesticides in agriculture including both intrinsic properties of the materials and environmental conditions. We also summarized the mechanisms of Zn-based NPs against phytopathogens including direct and indirect strategies to alleviate plant disease stress. Finally, the current challenges and future directions are highlighted to advance our understanding of this field and guide future studies.