Physiological response of different salt-tolerant oats to salt stress

This study aimed to investigate the physiological response of different salt-tolerant oats to salt stress, using Qingyongjiu 195 (salt-tolerant) and 709 (salt-sensitive) as test materials. Three-week-old oat seedlings grown in sand culture were treated with Hoagland nutrition containing 150 mmol·L⁻¹ NaCl for 0 (CK), 6, 24, and 72 h, and the effects of salt stress on photosynthesis, antioxidant properties, and osmotic regulation of the two oat seedlings were investigated. The results showed that the chlorophyll content, net photosynthetic rate (P_n), transpiration rate (T_r), stomatal conductance (G_s), intercellular carbon dioxide concentration (C_i), and K⁺ content of oat seedling leaves showed a decreasing trend with the extension of treatment time. The trend of peroxidase (POD), superoxide dismutase (SOD) activity, proline, and soluble sugar content first increased and then decreased, while other indices, including catalase (CAT) activity, malondialdehyde (MDA), and Na⁺ content showed an increasing trend. Under salt stress, the range of descent of chlorophyll content, P_n, T_r, and G_s in salt-tolerant Qingyongjiu 195 was less than that in salt-sensitive 709, whereas its SOD, CAT, proline content, and soluble sugar content were higher than that in 709, and MDA content was lower than that in 709. After salt stress at 6 and 24 h, the contents of K⁺ and Na⁺ in the roots of Qingyongjiu 195 were lower than that in 709, and higher than that in 709 at 72 h. After salt stress at 6 and 24 h, the content of K⁺ in the leaves of Qingyongjiu 195 was higher than in 709, whereas the content of Na⁺ was lower than that in 709. Overall, our study showed that salt-tolerant Qingyongjiu 195 possessed superior adjustment ability, antioxidant enzyme activity, and biofilm stability.