Foliar application of selenium nanoparticles, multiwalled carbon nanotubes and their hybrids stimulates plant growth and yield characters in rice (Oryza sativa L.) under salt stress

Salt stress (NaCl) is a major abiotic factor that severely affects plant growth and crop yield, with rice (Oryza sativa L.) being particularly vulnerable. Excessive soil salinity has been shown to significantly reduce rice productivity, posing a threat to global food security. To mitigate these adverse effects, research has increasingly focused on using nanomaterials to enhance plant tolerance to salt stress. This study investigates the potential of selenium nanoparticles (SeNPs), multiwalled carbon nanotubes (MWCNTs), and their hybrid form (SeNPs+MWCNTs) in alleviating NaCl-induced stress in rice plants exposed to 50 mM and 100 mM NaCl. Nanoparticle synthesis, hybridization, and localization in the foliar parts of the plants were confirmed using Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy (FTIR), and fluorescence microscopy with methylene blue dye, respectively. Among the treatments, SeNPs+MWCNTs hybrids (160 µg/mL) demonstrated the most promising effects, significantly enhancing various growth and yield parameters under saline conditions. Notably, this treatment improved shoot length (17 %), root length (14 %), and key yield traits, including shoot dry weight (32 %), root dry weight (31 %), total dry weight (32 %), number of panicles (31 %), panicle length (19 %), panicle weight (22 %), number of spikes per panicle (28 %), spike length (18 %), spike weight (19 %), number of fertile spikelets (32 %), and 100-grain weight (29 %) compared to the individual SeNPs and MWCNTs treatments. These findings provide valuable insights into the potential application of nanomaterials for improving rice growth under saline stress.