Seleiman Mahmoud F, Ahmad Awais, Tola ElKamil, Alhammad Bushra Ahmed, Almutairi Khalid F, Madugundu Rangaswamy, Al-Gaadi Khalid A
Plant Production Department, College of Food and Agriculture Sciences, King Saud University, P.O. Box 2460, Riyadh 11451, Saudi Arabia.
Department of Crop Sciences, Faculty of Agriculture, Menoufia University, Shibin El-Kom 32514, Egypt.
Plants (Basel). 2023 Oct 13;12(20):3559. doi: 10.3390/plants12203559.
Salinity is one of the major environmental stresses threatening crop production, the natural ecosystem, global food security, and the socioeconomic health of humans. Thus, the development of eco-friendly strategies to mitigate saline stress and/or enhance crop tolerance is an important issue worldwide. Therefore, this study was conducted during the summer of 2022 to investigate the potential of 24-Epibrassinolide (EBL) for mitigating saline stress and improving photosynthetic capacity, antioxidant defense systems, mineral uptake, and yield in maize ( L.) grown under a controlled hydroponic system. Three saline stress levels-S1 (control/no added NaCl), S2 (60 mM NaCl), and S3 (120 mM NaCl)-were continuously applied with nutrient solution, whereas exogenous EBL (i.e., control, 0.1 µM and 0.2 µM) was applied as exogenous application three times (i.e., 40, 55, 70 days after sowing). The experiment was designed as a split-plot in a randomized complete block design (RCBD) in which saline stress was the main factor and EBL treatment was the sub-factor. Results showed that saline stress significantly affected plant growth, physiological performance, biochemistry, antioxidant activity, and yield attributes. However, the exogenous application of EBL at 0.2 µM significantly mitigated the salt stress and thus improved plant performance even under 120 mM NaCl saline stress. For instance, as compared to untreated plants (control), 0.2 µM EBL application improved plant height (+18%), biomass (+19%), SPAD (+32%), Fv/Fm (+28%), rate of photosynthesis (+11%), carboxylation efficiency (+6%), superoxide dismutase (SOD +14%), catalase (CAT +18%), ascorbate peroxidase (APX +20%), K (+24%), 100-grain weight (+11%), and grain yield (+47%) of maize grown under salt stress. Additionally, it resulted in a 23% reduction in Na accumulation in leaves and a 25% reduction in for Na/K ratio under saline stress as compared to control. Furthermore, the Pearson's correlation and principal component analysis (PCA) highlighted the significance of exogenous EBL as saline stress mitigator in maize. Overall, our results indicated the protective effects of EBL application to the alleviation of saline stress in crop plants. However, further exploration of its mechanism of action and crop-specific response is suggested prior to commercial use in agriculture.
盐度是威胁作物生产、自然生态系统、全球粮食安全以及人类社会经济健康的主要环境胁迫因素之一。因此，制定生态友好型策略以减轻盐胁迫和/或增强作物耐受性是全球范围内的一个重要问题。为此，本研究于2022年夏季开展，旨在探究24-表油菜素内酯（EBL）在可控水培系统中种植的玉米（L.）上减轻盐胁迫、提高光合能力、抗氧化防御系统、矿物质吸收及产量的潜力。通过营养液持续施加三种盐胁迫水平——S1（对照/不添加NaCl）、S2（60 mM NaCl）和S3（120 mM NaCl），而外源EBL（即对照、0.1 µM和0.2 µM）在播种后第40、55、70天进行三次外源施用。试验采用随机完全区组设计（RCBD）中的裂区设计，其中盐胁迫为主因素，EBL处理为副因素。结果表明，盐胁迫显著影响植株生长、生理性能、生物化学、抗氧化活性及产量属性。然而，0.2 µM的外源EBL施用显著减轻了盐胁迫，从而即使在120 mM NaCl盐胁迫下也改善了植株性能。例如，与未处理植株（对照）相比，施用0.2 µM EBL使盐胁迫下生长的玉米株高增加了18%、生物量增加了19%、叶绿素含量（SPAD）增加了32%、最大光化学效率（Fv/Fm）增加了28%、光合速率增加了11%、羧化效率增加了6%、超氧化物歧化酶（SOD增加了14%）、过氧化氢酶（CAT增加了18%）、抗坏血酸过氧化物酶（APX增加了20%）、钾含量增加了24%、百粒重增加了11%、籽粒产量增加了47%。此外，与对照相比，它使盐胁迫下叶片中的钠积累量减少了23%，钠/钾比降低了25%。此外，皮尔逊相关性分析和主成分分析（PCA）突出了外源EBL作为玉米盐胁迫缓解剂的重要性。总体而言，我们的结果表明了EBL施用对缓解作物盐胁迫的保护作用。然而，在农业商业应用之前，建议进一步探索其作用机制及作物特异性反应。
