Herein, greenhouse experiments were designed to reveal the role of nitrogen-doped carbon dots (N-CDs) in enhancing maize drought tolerance. Two humidity conditions were created: adequate watering (soil moisture, 75%) and drought stress (soil moisture, 35%). Corn seedlings were harvested after spraying the N-CD solution (5 mg·L–1) on maize leaves for 5 days. The results indicated that foliar application of N-CDs increased the net photosynthesis rate (28.6%) of maize, and the fresh and dry weights of roots and shoots increased by 224.5, 360.0, 230.8, and 63.3% under drought stress, respectively. N-CDs showed high reactive oxygen species (ROS)-scavenging activity, resulting in enhanced superoxide dismutase activity (26.7%) and reduced malondialdehyde enzyme activity (18.9%). Besides, N-CDs could be used as light-harvesting materials to improve the light utilization efficiency, upregulate psbA gene expression (81.7-fold), and promote fast synthesis of the D1 protein, which could repair photosystem II under drought stress. Therefore, foliar-sprayed N-CDs could improve photosynthesis through multiple pathways under drought stress: light harvesting, photoprotection, and light repairing. Then, N-CD exposure reduced the corn yield loss under drought by nearly 30% compared with those of the control groups in a full life cycle study. Therefore, this study found for the first time that N-CD-enabled nanoagriculture could ensure crop growth and yield under drought stress, which would be important for global crop cultivation and a promising alternative to deal with the global climate change.

In the current study, foliar spray with lanthanum (La) based nanomaterials (La10Si6O27 nanorods, La10Si6O27 nanoparticle, La­(OH)3 nanorods, and La2O3 nanoparticle) suppressed the occurrence of sheath blight (Rhizoctonia solani) in rice. The beneficial effects were morphology-, composition-, and concentration-dependent. Foliar application of La10Si6O27 nanorods (100 mg/L) yielded the greatest disease suppression, significantly decreasing the disease severity by 62.4% compared with infected controls; this level of control was 2.7-fold greater than the commercially available pesticide (Thifluzamide). The order of efficacy was as follows: La10Si6O27 nanorods > La10Si6O27 nanoparticle > La­(OH)3 nanorods > La2O3 nanoparticle. Mechanistically, (1) La10Si6O27 nanorods had greater bioavailability, slower dissolution, and simultaneous Si nutrient benefits; (2) transcriptomic and metabolomic analyses revealed that La10Si6O27 nanorods simultaneously strengthened rice systemic acquired resistance, physical barrier formation, and antioxidative systems. Additionally, La10Si6O27 nanorods improved rice yield by 35.4% and promoted the nutritional quality of the seeds as compared with the Thifluzamide treatment. A two-year La10Si6O27 nanorod exposure had no effect on soil health based on the evaluated chemical, physical, and biological soil properties. These findings demonstrate that La based nanomaterials can serve as an effective and sustainable strategy to safeguard crops and highlight the importance of nanomaterial composition and morphology in terms of optimizing benefit.

Innovative technology to increase efficient nitrogen (N) use while avoiding environmental damages is needed because of the increasing food demand of the rapidly growing global population. Soybean (Glycine max) has evolved a complex symbiosis with N-fixing bacteria that forms nodules to fix N. Herein, foliar application of 10 mg L −1 Fe 7 (PO 4 ) 6 and Fe 3 O 4 nanomaterials (NMs) (Fe-based NMs) promoted soybean growth and root nodulation, thus improving the yield and quality over that of the unexposed control, EDTA-control, and 1 and 5 mg L −1 NMs. Mechanistically, flavonoids, key signaling molecules at the initial signaling steps in nodulation, were increased by more than 20% upon exposure to 10 mg L −1 Fe-based NMs, due to enhanced key enzyme (phenylalanine ammonia-lyase, PAL) activity and up-regulation of flavonoid biosynthetic genes (GmPAL, GmC4H, Gm4CL, and GmCHS). Accumulated flavonoids were secreted to the rhizosphere, recruiting rhizobia for colonization. Fe 7 (PO 4 ) 6 NMs increased Allorhizobium by 87.3%, and Fe 3 O 4 NMs increased Allorhizobium and Mesorhizobium by 142.2% and 34.9%, leading to increased root nodules by 50.0% and 35.4% over the unexposed control, respectively. Leghemoglobin content was also noticeably improved by 8.2−46.5% upon Fe-based NMs. The higher levels of nodule number and leghemoglobin content resulted in enhanced N content by 15.5−181.2% during the whole growth period. Finally, the yield (pod number and grain biomass) and quality (flavonoids, soluble protein, and elemental nutrients) were significantly increased more than 14% by Fe-based NMs. Our study provides an effective nanoenabled strategy for inducing root nodules to increase N use efficiency, and then both yield and quality of soybean.

Crop disease represents a serious and increasing threat to global food security. Lanthanum oxide nanomaterials (La2O3 NMs) with different sizes (10 and 20 nm) and surface modifications (citrate, polyvinylpyrrolidone [PVP], and poly(ethylene glycol)) were investigated for their control of the fungal pathogen Fusarium oxysporum (Schl.) f. sp cucumerinum Owen on six-week-old cucumber (Cucumis sativus) in soil. Seed treatment and foliar application of the La2O3 NMs at 20–200 mg/kg (mg/L) significantly suppressed cucumber wilt (decreased by 12.50–52.11%), although the disease control efficacy was concentration-, size-, and surface modification-dependent. The best pathogen control was achieved by foliar application of 200 mg/L PVP-coated La2O3 NMs (10 nm); disease severity was decreased by 67.6%, and fresh shoot biomass was increased by 49.9% as compared with pathogen-infected control. Importantly, disease control efficacy was 1.97- and 3.61-fold greater than that of La2O3 bulk particles and a commercial fungicide (Hymexazol), respectively. Additionally, La2O3 NMs application enhanced cucumber yield by 350–461%, increased fruit total amino acids by 295–344%, and improved fruit vitamin content by 65–169% as compared with infected controls. Transcriptomic and metabolomic analyses revealed that La2O3 NMs: (1) interacted with calmodulin, subsequently activating salicylic acid-dependent systemic acquired resistance; (2) increased the activity and expression of antioxidant and related genes, thereby alleviating pathogen-induced oxidative stress; and (3) directly inhibited in vivo pathogen growth. The findings highlight the significant potential of La2O3 NMs for suppressing plant disease in sustainable agriculture.

Nanoenable agriculture has been rapidly developed. However, foliar application of nanofertilizers results in them dripping off the leaves, which would effectively limit their bioavailability. Herein, a nanocarrier method of using nanoporous SiO 2 (NanoSi) was found to enhance the adhesion of carbon dots (CDs) on crop leaf surfaces. Foliar application of NanoSi-CDs (10 mg•L −1 ) could significantly increase the net photosynthetic rate (Pn; 110.0−140.0%), fresh weight (327.1% in roots and 247.2% in shoots), and dry weight (212.0% in roots and 118.5% in shoots) of maize. Moreover, NanoSi-CDs showed a long-term promotion effect. Specifically, the Pn remained significantly increased on day 20 after spraying with NanoSi-CDs, whereas the CDs had no such effect at the same time. Furthermore, the rainfall simulation experiments demonstrated that the water resistances of NanoSi-CDs and CDs were 2.5 and 1.5 cm, respectively. Compared with the control, NanoSi-CDs could increase the Pn by 22.3% on the 20th day after rainfall. Collectively, NanoSi nanocarriers can be a promising method to improve the bioavailability of engineering nanomaterials in sustainable agriculture.