Abstract:

To investigate the regulatory effects of chitooligosaccharides （COS） on physiological characteristics of Brassica pekinensis seedlings under salt stress， the cultivar "Cold-tolerant Golden Empress" was used. Seedlings were foliar sprayed with 0 （CK）， 50， 100， 150， or 200 mg·L^-1 COS for 4 days and then subjected to salt stress with 150 mmol·L^-1 NaCl. The results showed that the 100 mg·L^-1 COS treatment significantly increased plant height and dry weight per plant under NaCl stress， increasing by 14.44% and 88.06%， respectively. It also significantly enhanced the activities of antioxidant enzymes peroxidase （POD） and catalase （CAT） by 16.41% and 33.77%， respectively， while significantly reducing malondialdehyde （MDA） content. Furthermore， the net photosynthetic rate （Pn）， transpiration rate （Tr）， and stomatal conductance （Gs） of the leaves were significantly increased by 28.26%， 41.67%， and 15.90%， respectively， whereas intercellular CO₂ concentration （Ci） was significantly reduced. Proline content also increased significantly. These results indicated that 100 mg·L^-1 COS effectively alleviates salt stress-induced damage in Brassica pekinensis seedlings by enhancing antioxidant defense and photosynthetic efficiency， providing a theoretical basis and technical support for stress-resistant cultivation of highland summer vegetables.

Key words: chitooligosaccharide, Brassica pekinensis, salt stress, physiological characteristics, photosynthetic parameters

摘要：

为探究壳寡糖（chitooligosaccharides，COS）对盐胁迫下娃娃菜幼苗生理特性的调控作用，以“耐寒金皇后”娃娃菜为材料，将0（CK）、50、100、150、200 mg·L^-1 COS喷施叶面4 d后，用150 mmol·L^-1 NaCl溶液对娃娃菜幼苗进行胁迫处理。结果发现，100 mg·L^-1 COS处理显著提高了NaCl胁迫下娃娃菜幼苗的株高和单株干重，增幅分别达14.44%和88.06%，同时显著提升抗氧化酶——过氧化物酶（peroxidase，POD）和过氧化氢酶（catalase，CAT）的活性，增幅分别为16.41%和33.77%，而丙二醛（malondialdehyde，MDA）含量显著下降；叶片净光合速率（Pn）、蒸腾速率（Tr）及气孔导度（Gs）显著提升，分别提高了28.26%、41.67%和15.90%，而胞间CO?浓度（Ci）显著降低，脯氨酸含量显著增加。结果表明，100 mg·L^-1 COS可通过增强抗氧化防御能力和光合效能，有效缓解盐胁迫对娃娃菜幼苗的伤害，为高原夏菜抗逆栽培提供了理论依据和技术支撑。

关键词: 壳寡糖, 娃娃菜, 盐胁迫, 生理特性, 光合参数