Seed nano-priming using silica nanoparticles: effects in seed germination and physiological properties of Stevia Rebaudiana Bertoni

Background This study aimed to assess the effects of different concentrations of silicon (Si) nutrient sources, including bulk silicon dioxide (bSiO(2)) and two types of silica nanoparticles, nSiO(2) (I) andnSiO(2) (II) at different concentrations of 1, 5, 10, 25, 50, and 100 ppm in the germination process of stevia. The priming experiment was conducted using a completely randomized design with three replicates to ensure the reliability of the results. Results All stevia seedlings subjected to nano-priming significantly improved the germination parameters. The germination percentage increased by 106%, reaching 68% in nano-primed seedlings. Similarly, the germination rate showed a remarkable increase of 128.12% at 7.3 day(-1). Additionally, the root, shoot, and seedling dry weight increased by 283%, 168.9%, and 220% and determined 0.092, 0.078, and 0.17 g plant(-1), respectively, compared to the control. Furthermore, seed priming with nSiO(2) (I) at a concentration of 10 ppm resulted in an increased catalase (CAT) activity (36.15Umg(-1) protein) and peroxidase (POX) activity (approximately 0.057 U.mg(-1) protein). Also, the highest sucrose amount was observed in the root (equal to 160.4 mu g g(-1) DW) and shoot (equal to 247 mu g g(-1) DW) of seedlings primed with 10 ppm of nSiO(2) (I). However, it should be noted that nano-priming at the highest concentration led to oxidative damage indicated by an increase in H2O2 concentration. Conversely, bSiO(2) demonstrated a lesser effect on improving germination, seedling growth, antioxidant activities, and biochemical attributes compared to nSiO(2) (I), nSiO(2) (II). Conclusions This study established that seed priming with nSiO(2) (I) at a concentration of 10 ppm was the most effective in enhancing germination percentage and rate, root/shoot/dry weight, biochemical attributes, and enzyme activities (such as a-amylase, CAT, and POX). The results suggested that seed priming with nSiO(2) (I) at the optimal concentration could improve the seed germination by enhancing the antioxidant system, starch metabolism, and ultimately protecting plants from oxidative damage.