Salt stress represents a significant abiotic stress factor that impedes the growth of rice. Nano-silicon has the potential to enhance rice growth and salt tolerance. In this experiment, the rice variety 9311 was employed as the test material to simulate salt stress via hydroponics, with the objective of investigating the mitigation effect of foliar application of nano-silicon on rice seedlings. The results demonstrated that NaCl stress markedly impeded the growth of rice seedlings after seven days of NaCl treatment. The foliar application of nano-silicon followed by NaCl stress alleviated the growth of rice seedlings, markedly improved the spatial conformation of the root system, and enhanced photosynthesis compared with that of NaCl stress alone. The activities of antioxidant enzymes were improved. The contents of antioxidants were increased, and the over-accumulation of ROS was reduced. Furthermore, the foliar application of nano-silicon was found to enhance the uptake of Si⁴⁺, K⁺, and Ca²⁺ in plants, while simultaneously reducing Na⁺ and Cl⁻ accumulation. Additionally, the content of IAA, CTK, GA, JA, and SA was increased, and ABA was decreased. In conclusion, the foliar application of nano-silicon has been demonstrated to alleviate salt stress injury and improve the growth of rice seedlings.

Salt stress inhibits rice seed germination. Strigolactone (GR24) plays a vital role in enhancing plant tolerance against salt stress. However, GR24’s impact on the metabolism of stored substances and endogenous hormones remains unclear. This study investigated the impact of exogenous GR24 on the metabolism of stored substances and endogenous hormones during the early stages of rice seed germination under salt stress. The results showed that salt stress significantly reduced the germination rate, germination potential, germination index, radicle length, germ length, and fresh and dry weights of the radicle and germ under salt stress. Pre-treatment (1.2 μmol L⁻¹ GR24) significantly reduced the inhibition of salt stress on rice seed germination and seedling growth. GR24 promoted the decomposition of starch by enhancing the activities of α-amylase, β-amylase, and total amylase and improved the levels of soluble sugars and proteins and the conversion rate of substances under salt stress. GR24 effectively enhanced the activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX); increased ascorbic acid (ASA) and glutathione (GSH) levels; and reduced malondialdehyde (MDA) content. This reduced the oxidative damage of salt stress. Furthermore, GR24 significantly increased the contents of strigolactones (SLs), auxin (IAA), gibberellin (GA3), cytokinin (CTK) as well as IAA/ABA, CTK/ABA, GA/ABA, and SL/ABA ratios and reduced abscisic acid (ABA) levels. The current findings indicate that GR24 effectively mitigates the adverse impact salt stress by regulating antioxidant enzyme activity and endogenous hormone balance.

Salt stress is one of the principal abiotic stresses limiting agricultural production and seriously inhibiting seed germination rates. This study selected the salt-tolerant rice variety HD961 and the salt-sensitive rice variety 9311 as experimental materials to investigate the physiological and metabolic effects of exogenous Spd seed priming on rice seeds and seedlings under NaCl stress. The experiment involved treating rice seeds with 0.1 mmol·L⁻¹ Spd and then subjecting them to 100 mmol·L⁻¹ NaCl stress for 24 h, with sampling for analysis at the 24 h and the four-leaf-one-heart stage. The results indicated that under NaCl stress, the rice’s germination and vigor indices significantly decreased. However, exogenous Spd seed priming reduced the accumulation of malondialdehyde, enhanced the capacity for osmotic adjustment, and increased the amylase and antioxidant activity by 50.07% and 26.26%, respectively. Under NaCl stress, the morphological development of rice seedlings was markedly inhibited, whereas exogenous Spd seed priming improved the aboveground and belowground biomass of the rice under stress conditions, as well as the content of photosynthetic pigments. It also reduced the damage to seedlings from electrical conductivity, helped maintain ionic balance, and promoted the excretion of Na⁺ and Cl⁻ and the absorption of K⁺ and Ca²⁺. In the salt-sensitive rice variety 9311, the soluble protein content increased by 15.12% compared to the salt-tolerant rice variety HD961, especially under 100 mmol·L⁻¹ NaCl stress, when the effect of exogenous Spd seed priming was more pronounced. In summary, these findings might provide new research perspectives and strategies for improving the salt tolerance of rice under NaCl stress.