Hardening of Plantlets by Using Silicon Dioxide Nanoparticles

The abundant availability of silicon (Si) in soil has long attracted the attention of scientists about its role and impact on plant metabolism. In recent years, Si has been widely researched and applied in field conditions for the purpose of increasing plant resistance to biotic and abiotic stresses. In plant micropropagation, several available studies have shown that the addition of Si as salt to the culture medium significantly improved the morphogenesis and growth of in vitro plantlets. It is well documented that plant organs are mechanically strengthened by the presence of Si in the form of SiO2 structures in the cell walls. This chapter aims to analyze the effect of nano-sized silica (SiO2NPs) (0.0, 0.1, 0.5, 1.0, 2.0, and 3.0 mg/L) in the culture medium on the hardening ability of in vitro plantlets, as well as the subsequent growth of plantlets in the nursery. The results showed that SiO2NPs had a strengthening effect on in vitro plantlets of begonia and passion fruit. Besides, such plantlets showed significantly higher survival rate and growth compared to the control—without SiO2NPs during acclimation under ex vitro conditions. The present results have also suggested the inclusion of Si in the form of SiO2NPs in some future commercial tissue culture media formulations for the purpose of producing robust plantlets.