Seed Priming with Nitric Oxide-Releasing Chitosan Nanoparticles Improves Early Development of Atlantic Forest Tree Seedlings

Studies conducted with crop species have demonstrated that seed nanopriming with nitric oxide (NO) donors is an effective strategy to enhance early seedling development. Given the limited information available on the application of this approach in trees, this exploratory study aimed to investigate the effects of seed priming with nanoencapsulated S-nitrosoglutathione (GSNO) on emergence, early growth and root hair traits of five native Atlantic Forest tree species (Heliocarpus popayanensis, Cecropia pachystachya, Cariniana estrellensis, Schinus terebinthifolia, and Senna macranthera). Seeds were primed with chitosan nanoparticles (NPs) containing different GSNO concentrations (0.1, 0.25, 0.5, 1, 2.5 and 5 mM), in addition to hydropriming and non-primed control treatments. Seedling emergence and growth parameters were evaluated. Seed priming with GSNO-loaded NPs promoted increases in primary and lateral root length and the root-to-shoot length ratio, although responses varied among species and concentrations. Heliocarpus popayanensis was the most responsive species, with optimal results obtained at GSNO concentrations between 1 and 2.5 mM. The treatment also promoted increases in root-hair incidence and/or length in C. pachystachya, C. estrellensis, S. terebinthifolia, and S. macranthera. Overall, the technique showed potential to improve the early development of Atlantic Forest tree seedlings under greenhouse conditions; however, its effectiveness is species-specific and concentration-dependent.