Deciphering the physiological response mechanisms of Miscanthus sinensis to salt-induced stress

Soil salinization is a growing concern that degrades soil quality and inhibits agricultural productivity. Miscanthus species have received wide attention because of their high calorific potential, their value as an energy plant, and their ability to maintain high biomass accumulation. However, most studies focused on the biochemical and physiological responses to salt stress while neglecting the osmotic adjustment processes and the contribution of both organic and inorganic substances to these processes. This study evaluates the response mechanism of Miscanthus sinensis to salt stress (0–300 mM of NaCl) by evaluating the growth and photosynthetic parameters, photosynthetic response to light, and contribution of organic and inorganic substances to osmotic potential. The results revealed that M. sinensis adopted Na ⁺ compartmentalization and reallocation of biomass to the aboveground parts to mitigate the negative impact of salinity stress. Specifically, Na⁺ accumulated more in the root and leaf, with an increment magnitude of 75.4–173.9 and 56.7–217.1 times, respectively. This was supported by the changing trend of the stem/leaf ratio (25.1 %–55.9 %) compared to the root/shoot ratio (12.3 %–18.3 %). Also, salt-induced stress decreased the leaf's water content and water use efficiency as a result of low intracellular osmosis, and to mitigate osmotic damage, M. sinensis enhanced the accumulation of proline. These results offer theoretical and scientific insights into managing the cultivation and improving the yield of M. sinensis and other energy herbaceous plants in saline soils.