Using the proper means to improve seed germination is of great significance in agriculture and forestry. Here, a meta-analysis was used to examine whether metal nanoparticle treatments have a specific effect on the seed germination and seedling growth of agricultural species. Using the Web of Science (1950–2021), PubMed (1950–2021), and Scopus (1950–2021) databases, a paper search was conducted using the following items (“nanoparticles” and “seed germination”, “nanomaterials” and “seed germination”) to filter the references in the title, abstract, and keywords of the published articles. The results indicated that nanoparticle (NP) treatments had a significantly positive effect on the final germination percentage (FGP), with a mean difference (MD) (that is, the overall effect) of 1.97 (0.96, 2.98) for the silver (Ag)-NP subgroup, 1.21 (0.34, 2.09) for the other-NP subgroup, 1.40 (0.88, 1.92) for the total based on the NP types, 1.47 (0.85, 2.09) for the “Concentrations: 50 mg/L” subgroup, and 0.82 (0.72, 0.93) for the total based on the NP concentrations. However, there was no statistical correlation between the nanoparticle concentrations and shoot length (SL), due to the inclusion of zero in the 95% CI of the overall effect. Therefore, Ag-NPs could increase the FGP more than other-NPs, while Zn-NPs enhanced RL more. Moreover, NPs at lower concentrations could improve the FGP and RL of crop species to a larger extent than NPs at higher concentrations. This meta-analysis can provide a reference for the nanoparticle treatment technology utilization in agricultural and forest seeds.

Nutrient loading in the fall is a practical way to improve seedling quality and has been proven to increase nutrient accumulation, translocation and utilization. Few studies have reported on the variation in free amino acids as a result of fall fertilization, especially for different seasonal needle habits (evergreen, deciduous). Therefore, a balanced two-factor factorial design with one fall fertilization treatment (10 mg N/seedling) and Chinese pine (Pinus tabulaeformis Carr.) and Prince Rupprecht’s larch (Larix principis-rupprechtii Mayr.) seedlings was used to examine growth response over one nursery season. Associated changes between fall fertilization, N storage and free amino acids were analyzed. Results showed that: (1) stem height, diameter and biomass for both species were similar between controls and fall fertilization treatments; (2) compared to controls, fall fertilization increased Chinese pine needle and root N by 17.7% and 36.9%, respectively. For Prince Rupprecht’s larch, fall fertilization resulted in 26.3% and 34.54% more N in stem and roots, respectively, than controls; (3) the three main amino acids in control and fertilization treatments in Prince Rupprecht’s larch seedlings were glutamine, arginine and proline, and in Chinese pine seedlings were glutamine, arginine and γ-amino butyric acid; (4) total amino acid contents were not significantly increased by fall fertilization, but glutamine in Chinese pine and Prince Rupprecht’s larch increased by 64.2% and 35.2%, respectively. Aboveground biomass of Prince Rupprecht’s larch had higher proline contents than Chinese pine, which suggests that the stress resistance of the aboveground tissue may be higher for Prince Rupprecht’s larch. The results indicate that different plant organs with various response are well adapted to nitrogen loading for nutrient storage in evergreen and deciduous conifer seedlings.