Brackish Water Irrigation Boosts honeysuckle (Lonicera japonica Thunb.)-Salt Tolerance by Regulating Sodium Partitioning and Potassium Homeostasis: Implications for Coastal Saline Soil

Yu Shi¹Xiaojie Wang²Kaipeng Zhang¹Xuepeng Liu¹Jiang Bao Xia¹Dongjie Zhang¹Xiaoshuai Zhang²Qiqi Cao¹Wenjun He^1*

• ¹Shandong University of Aeronautics, Binzhou, China
• ²Chinese Academy of Sciences Yantai Institute of Coastal Zone Research, Yantai, China

To address agricultural water scarcity in coastal regions and optimize brackish water utilization in China's Yellow River Delta, this study conducted a field experiment employing four irrigation levels—T1 (rainfed control), T2 (40 mm irrigation), T3 (80 mm irrigation), and T4 (120 mm irrigation)— arranged in a randomized complete block design with four replicates. At harvest, biomass was weighed, surface soil cations were determined by ion chromatography, Na+ and K+ concentrations in honeysuckle were measured using flame atomic absorption spectrophotometry, and oxidative stress was assessed through leaf malondialdehyde (MDA) and H2O2 levels. Investigating the effects of varying brackish water irrigation levels on soil ion dynamics and growth-physiological traits of honeysuckle (Lonicera japonica Thunb.) in coastal saline-alkali soils. Key findings reveal that increasing brackish irrigation volume: (1) significantly reduced topsoil cation accumulation, with T2, T3, and T4 showing Na+ reductions of 29.53%, 41.46%, and 59.31%, and K+ reductions of 33.58%, 46.77%, and 52.80% relative to T1; (2) Enhanced the leaf K+/Na+ ratio through selective Na+ partitioning and K+ homeostasis, T4 exhibited 165.45%, 89.90%, and 48.89% higher ratio than T1, T2, and T3, respectively, driven by 59.27%, leaf Na+ reduction and 7.24% K+ increase at highest irrigation, and (3) Alleviated salt-induced oxidative stress, reducing malondialdehyde (MDA) from 228.46 (T1) to 143.81 nmol·g-1 (T4) and decreasing hydrogen peroxide (H2O2) by 43.42% in T4. Concurrently, whole-plant biomass increased 8.8-fold under T4 (829.56 g) versus T1 (94.05 g). These results establish an optimized irrigation protocol enhancing agroecological productivity and pedological improvement in coastal saline-alkali lands, reducing freshwater dependency while advancing sustainable brackish water management.