【目的】探究外源水杨酸(salicylic acid,SA)对NaCl胁迫下银杏(Ginkgo biloba)的缓解机制,为解决盐碱地区银杏盐害问题、扩大银杏引种栽培、丰富盐碱地区植物景观提供理论依据。【方法】以4年生银杏苗为试验材料,采取盆栽试验法,分别设定50(N1)、100(N2)和200(N3)mmol/L NaCl浓度和0.02(S1)、0.10(S2)和0.50(S3)mmol/L SA不同浓度混合及未施加SA和NaCl的对照共13个处理组,处理时间为28 d,观察银杏生长的表观特征,测定与银杏生长和光合特征相关的12个指标,结合主成分分析和隶属函数法分析,筛选出对银杏盐胁迫缓解效果最好的水杨酸浓度。【结果】①随NaCl浓度的增加和胁迫时间的延长,银杏顶梢和叶片出现不同程度变黄、焦化和脱落的现象,叶鲜质量较对照组显著降低。②NaCl浓度的增加和胁迫时间的延长,会使银杏叶片的叶绿素a(Chla)含量、叶绿素b(Chlb)含量、总叶绿素(total Chl)含量、净光合速率(Pn)、气孔导度(Gs)、胞间CO₂浓度(Ci)、蒸腾速率(Tr)、最大光化学效率(F_v/F_m)、光化学猝灭系数(qP)、实际光化学量子产量[Y(Ⅱ)]和相对电子传递速率(ETR)降低。③施加适宜浓度的外源SA能缓解NaCl胁迫对银杏生长和光合特征的抑制作用,其中N1S2、N2S2和N3S2处理组缓解效果最好。④主成分分析和隶属函数法分析表明不同浓度外源SA对NaCL胁迫的缓解作用由大到小为0.10、0.02、0.50 mmol/L。【结论】NaCl胁迫能抑制银杏的生长和光合作用,NaCl胁迫下外源SA浓度0.10 mmol/L的缓解效果最佳,0.02 mmol/L次之,SA浓度0.50 mmol/L对NaCl胁迫的缓解作用效果不明显。

【Objective】This study investigated the alleviation mechanism of exogenous salicylic acid (SA) on Ginkgo biloba under NaCl stress, with the aim of providing a theoretical basis for addressing the salt damage of G. biloba in saline environments. This could support the expansion of G. biloba cultivation and enhance the plant landscape in these areas.【Method】Thirteen treatment groups were established with NaCl concentrations of 50 (N1), 100 (N2), and 200 (N3) mmol/L, and SA concentrations of 0.02 (S1), 0.10 (S2), and 0.50 (S3) mmol/L, using four-year-old G. biloba as the test material. The groups included CK, N1, N1S1, N1S2, N1S3, N2, N2S1, N2S2, N2S3, N3, N3S1, N3S2, and N3S3, with five replicates per group. The experiments were conducted in the greenhouse of Beijing Forestry University (116° 35'E, 40° 01'N) over a period of 28 days. The average temperature in the greenhouse was approximately 27.5 °C, and the average humidity is about 65.9%. This study observed the phenological characteristics of G. biloba growth and measured various indicators, including leaf fresh weight, chlorophyll a (Chla) content, chlorophyll b (Chlb) content, total chlorophyll (total Chl) content, net photosynthetic rate (Pn), stomatal conductance (Gs), intercellular CO₂ concentration (Ci), transpiration rate (Tr), maximal photochemical efficiency (F_v/F_m), photochemical quenching coefficient (qP), actual photochemical efficiency (Y(Ⅱ)), and electron transport rate (ETR). The optimal SA concentration for mitigating salt stress in G. biloba was determined through principal component analysis and affiliation function method analysis.【Result】(1) As the NaCl concentration increased and the stress duration extended, the branch tops and leaves of G. biloba exhibited varying degrees of yellowing, scorching, and abscission, with a significant reduction in leaf fresh weight compared to the control group. (2) Increasing NaCl concentration and prolonging stress durations decreased leaf fresh weight, Chla content, Chlb content, total Chl content, Pn, Gs, Ci, Tr, F_v/F_m, qP, Y(Ⅱ), and ETR in G. biloba. (3) The application of exogenous SA at appropriate concentrations alleviates the inhibitory effected of NaCl stress on the growth and photosynthetic characteristics of G. biloba. The N1S2, N2S2, and N3S2 treatment groups were the most effective in mitigating salt damage. (4) Principal component analysis indicated that the exogenous application of SA primarily enhanced salt tolerance by influencing eight indicators: leaf fresh weight, Chla content, Chlb content, total Chl content, Pn, Gs, Tr, and F_v/F_m. (5) Based on the principal component analysis and affiliation function method analysis, the mitigating effect of SA was ranked as follows: 0.10 mmol/L > 0.02 mmol/L > 0.50 mmol/L.【Conclusion】The SA at 0.02 and 0.10 mmol/L under NaCl stress is more effective in mitigating growth and photosynthesis in G. biloba, with 0.10 mmol/L SA showing the best mitigation effect and 0.50 mmol/L SA having a more limited effect. Growth indicators and photosynthetic properties are important reference indicators for assessing salt tolerance in plants. However, the plant responses to salt stress are complex, so this experiment can serve as one references, and further research at physiological, biochemical, and molecular levels is needed.