【目的】探讨红仁核桃(Juglans regia ‘Robert Livermore’)在盐碱(NaCl+NaHCO₃)复合胁迫下的生理生化动态响应机制,明确红仁核桃耐盐碱能力调节的变化规律。【方法】对红仁核桃实生幼苗进行盆栽控制试验,设置(NaCl+NaHCO₃)混合液3个浓度水平(100、150、200 mmol/L)作为胁迫处理,同时以水为对照(CK),在胁迫处理后的第7、14、21 天,分别测定幼苗的光合作用参数、荧光特性及多项生理指标。此外,对花青素合成途径中的关键基因进行表达水平鉴定,并运用Mantel-test统计方法分析花青素含量与这些关键基因表达之间的相关性。【结果】随着盐碱复合胁迫浓度增加和胁迫时间的延长,红仁核桃幼苗叶缘卷曲、焦枯程度不断加重,相对株高(relative growth in height,RGH)、相对地径(relative diameter growth,RDG)、叶片相对含水量(leaf relative water content,LRWC)和生物量均显著下降。短期胁迫时,苗木光合能力[净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(G_s)]迅速减弱,高盐碱条件下OJIP曲线上I、P点的相对荧光强度明显升高,伴随着电子传递效率[(单位活性反应中心吸收的光能(ABS/RC)]、暗适应样品开始照明时单位活性反应中心捕获的用于还原初级醌受体的能量(TR₀/RC)、t=0时单位活性反应中心捕获的用于传递的电子能量(ET₀/RC)、单位活性反应中心耗散的能量(DI₀/RC)均下降。胁迫后期由于超氧化物歧化酶(SOD)和过氧化物酶(POD)的活性持续升高,丙二醛(MDA)和过氧化氢(H₂O₂)含量有下降趋势。次生代谢物类黄酮、多酚随着胁迫的增强含量持续积累。对生理参数进行主成分分析,结果表明短期胁迫下能通过提高次生代谢物(类黄酮、多酚和花青素)的含量清除过量的活性氧(ROS),随着胁迫时间的延长,渗透调节物质[可溶性蛋白(SP)和脯氨酸(Pro)]显著增加。【结论】红仁核桃在盐碱(NaCl+NaHCO₃)复合胁迫下,生长受抑制,光合效率下降,短期胁迫下通过增强抗氧化酶活性和积累次生代谢物清除过量ROS,且JrAOMT基因上调促进花青素合成,长期胁迫下通过调节SP和Pro含量提高渗透调节能力以维持对胁迫环境的适应性。

【Objective】This study aims to investigate the dynamic physiological and biochemical responses of Juglans regia ‘Robert Livermore’ seedlings to a combined saline-alkali stress, and to clarify the regulatory patterns of their saline-alkali tolerance capacity.【Method】Potted seedling control experiments were conducted using three concentration levels (100, 150 and 200 mmol/L) of a (NaCl+NaHCO₃) mixed solution as the stress treatment groups, with water as the control group (CK). On the 7th, 14th and 21st day after stress initiation, photosynthetic parameters, chlorophyll fluorescence characteristics, and various physiological indicators were measured. Furthermore, the expression levels of key genes in the anthocyanin biosynthesis pathway were determined, and the correlation between anthocyanin content and the expression of these key genes was analyzed using mantel-test statistics.【Result】With increasing stress concentration and duration, leaf margin curling and scorching intensified significantly, while relative growth in height (RGH), relative diameter growth (RDG), leaf relative water content (LRWC), and biomass all decreased markedly. Under short-term stress, photosynthetic capacity (net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (G_s)) declined rapidly. Under high saline-alkali conditions, the relative fluorescence intensities at points I and P on the OJIP curve increased significantly, accompanied by a decrease in electron transport efficiency (ABS/RC, TR_o/RC, ET_o/RC, DI_o/RC). In the later stages of stress, superoxide dismutase (SOD) and peroxidase (POD) activities continued to increase, leading to a declining trend in malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) contents. The contents of secondary metabolites, flavonoids and polyphenols, accumulated continuously with increasing stress intensity. Principal component analysis of physiological parameters indicated that under short-term stress, the clearance of excess reactive oxygen species (ROS) was facilitated by increased levels of secondary metabolites such as flavonoids, polyphenols, and anthocyanins. As stress duration extended, osmotic adjustment substances (soluble protein and proline) increased significantly.【Conclusion】Under combined NaCl and NaHCO₃ stress, the growth of J. regia ‘Robert Livermore’ seedlings was inhibited and photosynthetic efficiency declined. Short-term stress triggered enhanced antioxidant enzyme activity and accumulation of secondary metabolites to scavenge excess ROS, accompanied by upregulation of the JrAOMT gene promoting anthocyanin synthesis. Under the long-term stress, osmotic adjustment capacity was improved by regulating SP and Pro contents to maintain adaptability to the stressful environment.