关键词: 杜仲, β-氨基丁酸, 盐胁迫, 叶绿素, 气体交换参数, 激素

Abstract: To alleviate the negative effects of salt stress on the germination and growth of Eucommia ulmoides seeds，salt free treatment was used as the control（CK）to investigate the effects of soaking E.ulmoides seeds in different concentrations of β‑aminobutyric acid（BABA）（5，10，20，40，80，160 mmol/L，denoted as BA₁，BA₂，BA₃，BA₄，BA₅，BA₆）under 100 mmol/L salt stress（SS）on seed germination and seedling growth，gas exchange parameters，key enzymes and antioxidants in the ascorbic acid（AsA）‑glutathione（GSH）cycle，and hormone metabolism.The results showed that under salt stress，the germination，seedling growth，and physiological processes of E.ulmoides seeds were inhibited，and the AsA‑GSH cycle and hormone metabolism balance were disrupted. Different concentrations of BABA treatment could alleviate the inhibition of salt stress on E.ulmoides seed germination and enhance the salt resistance of seedlings.Compared with SS treatment，SS+BA₂ treatment increased the germination rate，germination vigor，germination index，and vitality index of E.ulmoides seeds by 74.1%，85.6%，87.9%，and 84.3%，respectively.The height，leaf area，and fresh weight（aboveground and root systems） of seedlings showed varying degrees of increase.Among the various concentrations of BABA treatment，SS+BA2 treatment had the best effect on improving the content of chlorophyll a，chlorophyll b，total chlorophyll，and carotenoids in seedlings，increasing by 49.3%，112.5%，64.2%，and 54.8% respectively compared to SS treatment. The net photosynthetic rate（Pn），transpiration rate（Tr），and stomatal conductance（Gs） in gas exchange parameters increased by 51.8%，88.9%，and 44.7% respectively，while the intercellular CO₂ concentration（Ci）decreased by 46.5%. Under salt stress，the soaking with different concentrations of BABA increased the activities of ascorbate peroxidase（APX），glutathione reductase（GR），monodehydroascorbate reductase（MDHAR），dehydroascorbate reductase（DHAR），and the contents of AsA and GSH in E. ulmoides seedlings. Compared with SS treatment，SS+BA₂ treatment increased the activities of APX，GR，MDHAR，DHAR，and the contents of AsA and GSH by 142.7%，126.0%，167.2%，169.4%，103.8%，and 132.3%，respectively； the content of indole‑3‑acetic acid（IAA）reached its maximum value of 39.2 ng/g in SS+BA₂ treatment，and the content of gibberellin（GA₃）and zeaxanthin nucleoside（ZR）also showed an increasing trend.In conclusion，treating E.ulmoides seeds with 10 mmol/L β‑aminobutyric acid showed the most significant effect in
alleviating the negative effects of salt stress.

Key words: Eucommia ulmoides, β?aminobutyric acid, Salt stress, Chlorophyll, Gas exchange parameter, Hormone