The present study was aimed to investigate the protective role of silicon (Si) from salt-induced damages in alfalfa. Seedlings were treated with 200 mM NaCl plus three silicon levels (0, 0.75 and 1.5 mM) for 1 week. We observed that salt stress impacted plant growth remarkably, including height, root length, stem and leave weight, aboveground biomass and total biomass, chlorophyll a (chl a), chlorophyll b (chl b), total chlorophyll (total chl), chlorophyll fluorescence, K concentration and K/Na ratio. Consequently, electrolyte leakage (EL), superoxide dismutase (SOD) activity, Na concentration, proline, malondialdehyde (MDA), soluble sugar (SS) and soluble protein (SP) content were found to be raised significantly. After exogenously applying Si under salt stress, the EL, MDA, proline and Na content, except SOD activity, were observed to be dropped. Meanwhile, the chl a, chl b, and total chl and SS content, and chlorophyll fluorescence were found to be elevated. In terms of Si concentration, we found that the protective effects of Si were considerably better at lower concentration (0.75 mM) than higher (1.5 mM) one. Collectively, our results suggested that Si alleviate salt-induced damage and promote alfalfa growth by changing physiological characteristics.

中文翻译：

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外源施硅改善盐对苜蓿的损伤

本研究旨在研究硅 (Si) 对紫花苜蓿盐害的保护作用。用 200 mM NaCl 加三种硅水平（0、0.75 和 1.5 mM）处理幼苗 1 周。我们观察到盐胁迫对植物生长的影响显着，包括高度、根长、茎叶重量、地上生物量和总生物量、叶绿素a（chl a）、叶绿素b（chl b）、总叶绿素（total chl）、叶绿素荧光, K 浓度和 K/Na 比值。因此，发现电解质泄漏（EL）、超氧化物歧化酶（SOD）活性、Na浓度、脯氨酸、丙二醛（MDA）、可溶性糖（SS）和可溶性蛋白（SP）含量显着升高。盐胁迫下外源施Si后，除SOD活性外，EL、MDA、脯氨酸和Na含量均下降。同时，发现叶绿素a、叶绿素b、总叶绿素和SS含量以及叶绿素荧光升高。就 Si 浓度而言，我们发现 Si 的保护作用在较低浓度 (0.75 mM) 下比在较高浓度 (1.5 mM) 下要好得多。总的来说，我们的研究结果表明，Si 通过改变生理特性来减轻盐引起的损伤并促进紫花苜蓿的生长。