Urmi Tahmina Akter, Islam Md Moshiul, Zumur Kamrun Naher, Abedin Md Anwarul, Haque M Moynul, Siddiqui Manzer H, Murata Yoshiyuki, Hoque Md Anamul
Department of Soil Science, Faculty of Agriculture, Bangladesh Agricultural University, Mymensingh 2202, Bangladesh.
Department of Agronomy, Faculty of Agriculture, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur 1706, Bangladesh.
Antioxidants (Basel). 2023 Jul 18;12(7):1438. doi: 10.3390/antiox12071438.
Salicylic acid (SA) and proline exhibit protective effects against a wide range of stresses. However, the combined impact of SA and proline on rice under drought stress is still unknown. Therefore, we investigated the protective roles of SA and/or proline in conferring drought tolerance in rice. There were eight treatments comprising the control (T1; 95-100% FC), 1.5 mM SA (T2), 2 mM proline (T3), 0.75 mM SA + 1 mM proline (T4), 45-50% FC (T5, drought stress), T5 + 1.5 mM SA (T6), T5 + 2 mM proline (T7), and T5 + 0.75 mM SA + 1 mM proline (T8), and two rice varieties: BRRI dhan66 and BRRI dhan75. Drought stress significantly decreased the plant growth, biomass, yield attributes, photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (Tr), photosynthetic pigments (chlorophyll and carotenoids content), relative water content (RWC), membrane stability index (MSI), soluble sugar and starch content, and uptake of N, P and K in roots and shoots. Drought-induced oxidative stress in the form of increased hydrogen peroxide (HO) production and lipid peroxidation (MDA) was observed. The combined application of SA (0.75 mM) + proline (1 mM) was found to be more effective than the single application of either for drought stress mitigation in rice. A combined dose of SA + proline alleviated oxidative stress through boosting antioxidant enzymatic activity in contrast to their separate application. The application of SA + proline also enhanced proline, soluble sugar and starch content, which resulted in the amelioration of osmotic stress. Consequently, the combined application of SA and proline significantly increased the gas exchange characteristics, photosynthetic pigments, RWC, MSI, nutrient uptake, plant growth, biomass and yield of rice. Therefore, the combined application of SA and proline alleviated the detrimental impacts of drought stress more pronouncedly than their separate application did by increasing osmoprotectants, improving nutrient transport, up-regulating antioxidant enzyme activity and inhibiting oxidative stress.
水杨酸（SA）和脯氨酸对多种胁迫具有保护作用。然而，SA和脯氨酸对干旱胁迫下水稻的综合影响仍不清楚。因此，我们研究了SA和/或脯氨酸在赋予水稻耐旱性方面的保护作用。试验设置了八个处理，包括对照（T1；95 - 100%田间持水量）、1.5 mM SA（T2）、2 mM脯氨酸（T3）、0.75 mM SA + 1 mM脯氨酸（T4）、45 - 50%田间持水量（T5，干旱胁迫）、T5 + 1.5 mM SA（T6）、T5 + 2 mM脯氨酸（T7）以及T5 + 0.75 mM SA + 1 mM脯氨酸（T8），选用了两个水稻品种：BRRI dhan66和BRRI dhan75。干旱胁迫显著降低了水稻的植株生长、生物量、产量性状、光合速率（Pn）、气孔导度（gs）、蒸腾速率（Tr）、光合色素（叶绿素和类胡萝卜素含量）、相对含水量（RWC）、膜稳定性指数（MSI）、可溶性糖和淀粉含量，以及根系和地上部对氮、磷、钾的吸收。观察到干旱诱导的氧化应激表现为过氧化氢（HO）生成增加和脂质过氧化（MDA）。结果发现，SA（0.75 mM） + 脯氨酸（1 mM）联合施用在缓解水稻干旱胁迫方面比单独施用更有效。与单独施用相比，SA + 脯氨酸联合剂量通过提高抗氧化酶活性减轻了氧化应激。SA + 脯氨酸的施用还提高了脯氨酸、可溶性糖和淀粉含量，从而缓解了渗透胁迫。因此，SA和脯氨酸联合施用通过增加渗透保护剂、改善养分运输、上调抗氧化酶活性和抑制氧化应激，比单独施用更显著地减轻了干旱胁迫的不利影响。
