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.

Chinese pistache tree (Pistacia chinensis Bunge, Anacardiaceae) is an important oil, ornamental and afforestation tree species. Seeds of this species are known due to their erratic germination, so it is urgent to determine the causes of such dormancy. To do so, we tested water permeability, respiration rate, mechanical constraint and germination inhibitors. The results indicated that the testa was water-permeable, the raphe and hilum as the areas that contributed most to imbibition. Removal of the testa increased the imbibition rate and improved the oxygen availability to the embryo. Furthermore, the analysis of the extracts showed that the endotesta and embryo may contain inhibitors that negatively affect germination and seedling growth. The widely targeted metabolomics revealed that phenolic acids and organic acids may be the potential inhibitors. Seed scarification, exogenous gibberellin (GA₃) and cold stratification greatly increased the germination, but seed scarification (removal of the exotesta and 1/2 cotyledon) was the most effective strategy, since it increased the germination up to 89% after 5 days of incubation, a rate significantly higher regarding the other strategies, which barely reached 60% in 20 days. In conclusion, there seems to exist both a mechanical dormancy due to the testa and a physiological inhibition due to the embryo.