Abstract:

Plant growth in coastal estuarine riparian zones is vulnerable to combined waterlogging and salt stresses. Previous studies have shown that Syzygium nervosum A. Cunn. ex DC. and Syzygium cumini (L.) Skeels possess strong waterlogging tolerance. However, their tolerance to combined salinity and waterlogging stress is still unclear. In this study, three treatments, including waterlogging, salinity treatment (350 mmol/ L), and combined salinity-waterlogging treatment (175 mmol/L), were used to compare the effects of different stresses on plant growth, physiological and biochemical traits, and ion accumulation in both species. After 24 d of treatment, the three stress treatments resulted in a decrease in the biomass of both species, as well as an increase in reduced glutathione (GSH) content and activities of ascorbate peroxidase (APX) and glutathione reductase (GR). Compared to the control, waterlogging treatment decreased the contents of superoxide anion (O₂⁻) and hydrogen peroxide (H₂O₂) in the leaves of both species, while increasing the potassium ion (K⁺) content and decreasing the K⁺/Na⁺ ratio in the roots. Compared to the control, salinity treatment decreased the O₂⁻ content in the S. cumini seedlings but increased content in the S. nervosum seedlings. In addition, salinity treatment increased the contents of proline, H₂O₂, sodium ion (Na⁺), and chloride ion (Cl⁻) in both species but decreased the K⁺/Na⁺ ratio. Compared to the control, combined salinity-waterlogging treatment increased the contents of O₂⁻, Na⁺, and Cl⁻ in both species but decreased the K⁺/Na⁺ ratio. In addition, compared to the waterlogging treatment, combined salinity-waterlogging treatment decreased biomass accumulation in both species, while increasing the contents of O₂⁻, Na⁺, and Cl⁻. Compared to the S. nervosum seedlings, the S. cumini seedlings exhibited higher biomass accumulation, proline content, GR activity, and K⁺/Na⁺ ratio, and lower levels in H₂O₂, Na⁺, and Cl⁻ under salinity treatment and combined salinity-waterlogging treatment, suggesting that S. cumini seedlings possess stronger tolerance to salinity and combined salinity-waterlogging than S. nervosum. These findings provide theoretic guidance for vegetation restoration and reconstruction in coastal estuarine wetland systems.

摘要：

滨海河口河岸带植物易受到水淹和盐复合胁迫的影响。前期研究表明水翁（Syzygium nervosum A. Cunn. ex DC.）和乌墨（Syzygium cumini (L.) Skeels）具有较强的耐水淹能力，然而两种植物对水淹-盐复合胁迫的耐受性尚不清楚。本研究设置水淹、盐（350 mmol/L）及水淹-盐（175 mmol/L）复合胁迫3种胁迫处理，比较两物种对不同胁迫的生长、生理生化和盐胁迫相关离子积累的响应。结果显示，经过24 d处理，3种胁迫处理均低了两物种的生物量，提高了还原型谷胱甘肽（GSH）含量、抗坏血酸过氧化物酶（APX）和谷胱甘肽还原酶（GR）的活性。水淹胁迫下两物种的超氧阴离子（O₂^·−）和过氧化氢（H₂O₂）含量下降，根系K⁺含量上升，K⁺/Na⁺下降；盐胁迫下乌墨幼苗O₂^·−含量下降，水翁幼苗O₂^·−含量上升，两物种幼苗的脯氨酸含量、H₂O₂含量、Na⁺、Cl^-含量上升，K⁺/Na⁺下降；水淹-盐复合胁迫下两物种的O₂^·−、Na⁺、Cl^-含量上升，K⁺/Na⁺下降。此外，与水淹相比，水淹-盐复合胁迫降低了两物种的生物量，提升了两物种的O₂^·−、Na⁺、Cl^-含量。与水翁相比，乌墨幼苗在盐、水淹-盐复合胁迫下有较高的生物量、脯氨酸含量、GR活性和K⁺/Na⁺，以及较低的H₂O₂、Na⁺和Cl^-含量，具有更强的盐、水淹-盐复合胁迫耐受能力。