Silver nanoparticles and silver ions differentially affect the phytohormone balance and yield in wheat

This study aimed to examine the hypothesis that silver nanoparticles (AgNPs) and silver ions might induce specific changes and thereby affect plant development and final yield. The experiment was performed on spring wheat, cultured hydroponically with two types of negatively charged AgNPs of an average size of 13–15 nm and silver ions for 14 days and then transplanted to pots with soil. Our results indicated that treatment with the AgNPs stabilized by specific compounds resulted in growth promotion and a reduced number of days to flowering, while that with the ionic form of Ag only caused greater growth in height without influencing the time to heading. Accelerated flowering was caused by changes in phytohormone balance, with GA6 found to be especially favorable. Nanoparticles and silver ions affected the function of photosystem II and the transport and partitioning of assimilates. Increases in the transport form of sugars such as sucrose, raffinose and sorbitol were associated with a considerable improvement in wheat yield, especially in the case of plants treated with the nanoparticle forms, which were more stable and resistant to oxidative dissolution.