Effects of Foliage Spraying with Sodium Bisulfite on the Photosynthesis of Orychophragmus violaceus
2021
Li, Zhongying | Wu, Yanyou | Xing, Deke | Zhang, Kaiyan | Xie, Jinjin | Yu, Rui | Chen, Tian | Duan, Rongrong
Sulphurous acid derived from sulfur dioxide (SO₂) emission leads to the pollution of irrigation water and the inhibition of plant growth. The safe concentration threshold of NaHSO₃ in plants should be clarified to promote agricultural production. In this study, Orychophragmus violaceus seedlings were used as experimental materials and five NaHSO₃ concentrations (i.e., 0, 1, 2, 5, 10 mmol·L⁻¹) were simultaneously sprayed on the leaf surface of different seedlings separately. Leaf physiology responses under different concentrations were analyzed. The NaHSO₃ did not promote photosynthesis in O. violaceus under the 1 and 2 mmol·L⁻¹ treatments. It was conducive to the net photosynthetic rate (PN), photorespiration rate (Rₚ), chlorophyll content, actual photochemical quantum yield (YII) and photochemical quenching (qP) under the 5 mmol·L⁻¹ treatment. However, quantum yield of regulated energy dissipation (YNPQ) and nonphotochemical quenching (NPQ) were inhibited. Under the 10 mmol·L⁻¹ treatment, PN, chlorophyll content, YII, qP, dark respiration rate (Rd) and electron transport rate (ETR) showed significant decreases, while the photorespiration portion (Sₚ) significantly increased. Our results demonstrated that NaHSO₃ provided a sulfur source for plant growth and interfered with the redox reaction of the plant itself, and its role as a photorespiratory inhibitor might be masked.
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