【目的】探究盐涝交互作用对杂交新美柳(Salix matsudana × alba)生长及生理的影响,揭示盐涝胁迫下杂交新美柳的抗逆生理变化规律。【方法】选取1年生杂交新美柳扦插苗为研究对象,设置正常水分与淹水两个水分条件,4种质量分数NaCl(分别为0、0.2%、0.4%、0.6%)胁迫处理,以无盐正常水分为对照,分别于胁迫后3、10、17、24、41和60 d取样,测定胁迫过程中的苗高、地径、生物量、超氧化物歧化酶(SOD)活性、过氧化物酶(POD)活性、丙二醛(MDA)含量、可溶性糖(SS)含量、可溶性蛋白(SP)含量、脯氨酸(Pro)含量、根系活力、叶绿素含量等指标,分析盐涝交互对杂交新美柳生长和生理的影响。【结果】低盐涝胁迫促进苗木高生长,高浓度盐涝胁迫抑制苗木高生长。盐涝交互下杂交新美柳相对电导率与MDA含量呈上升趋势,抗氧化酶活性比单一胁迫时更高,SOD酶活性比POD酶活性更快响应。与单盐胁迫相比,盐涝胁迫24 d时SS含量显著下降,17 d时SP含量显著升高,Pro含量呈先升后降再升的趋势;根系活力都大于单盐胁迫,叶绿素含量呈下降趋势并显著低于单盐胁迫。正常水分条件下杂交新美柳对盐分的耐受阈值为0.65%(111.22 mmol/L),淹水条件下对盐分的耐受阈值为0.42%(71.87 mmol/L),具有较强的耐受性。【结论】盐涝胁迫下,渗透调节系统、保护酶系统对盐涝胁迫响应程度较高,这是影响杂交新美柳幼苗对盐涝胁迫适应能力的重要因素,生物量、MDA含量、根系活力等指标可作为杂交新美柳幼苗水盐耐性评价指标。

【Objective】 This study aimed to examine the effects of salt and flooding interactions on the growth and physiological responses of Salix hybrid, focusing on the physiological mechanisms underlying its tolerance to salt-flooding stress. 【Method】One-year-old Salix hybrid cuttings were subjected to two water conditions—normal watering and flooding—and four salinity levels (0%, 0.2%, 0.4%, and 0.6% mass fraction of NaCl), with normal water without salt serving as the control. Samples were collected at six time points (3, 10, 17, 24, 41, and 60 days post-treatment) to measure seedling height, root collar diameter, biomass, and physiological indicators, including superoxide dismutase (SOD), peroxidase (POD) activities, malondialdehyde (MDA), soluble sugar (SS), soluble protein (SP), proline (Pro) content, root vigor, and chlorophyll content. These parameters were analyzed to evaluate the effect of salt-flooding interactions on the growth and physiology of the Salix hybrid. 【Result】Low salinity under flooding conditions promoted seedling elongation, whereas high salinity under flooding inhibited growth. Relative electrical conductivity and MDA levels exhibited a continuous increase under combined salt and flooding stress. Antioxidant enzyme activity was more pronounced under the combined stress than under individual stress conditions, with SOD activity responding more rapidly than POD activity. Compared to salt stress alone, SS content significantly decreased on 24 days, SP content increased significantly on 17 days, and Pro content showed an initial increase, followed by a decline and subsequent recovery. Root vigor was higher under salt-flooding stress than that under salt stress alone, while chlorophyll content decreased significantly and remained lower than that under single salt stress.【Conclusion】The Salix hybrid demonstrated a robust osmoregulatory and protective enzyme system in response to salt-flooding stress, which played a critical role in its adaptive capacity. Biomass, MDA levels, and root vigor were identified as key indicators for assessing water and salt tolerance. The salinity tolerance threshold was determined to be 0.65% (111.22 mmol/L) under normal water conditions and 0.42% (71.87 mmol/L) under flooded conditions, indicating the Salix hybrid’s strong salinity tolerance. This study provides theoretical and practical insights into the physiological mechanisms of the Salix hybrid under salt-flooding stress, offering valuable guidance for its cultivation in saline and waterlogged environments.