The current investigation aimed to evaluate the role of silicon forms on sweet basil ( Ocimum basilicum L.) biomass and essential oil (EO) production, as well as some physiological and ultrastructural modification under different irrigation regimes. Drought significantly decreased plant growth, photosynthetic pigment, ion, relative water content, catalase activity, and EO yield, meanwhile, increased organic and antioxidant solute concentration, EO percentage, peroxidase activity, and oxidative impairment criteria (hydrogen peroxide, lipid peroxidation, and membrane permeability percentage). Concerning EO constituents, linalool and methyl chavicol were the major components that decreased under drought relative to well-watered plants. Exogenous application of silicon forms under well-watered or drought condition may fully or partially compensate to some extent to sweet basil plant development and biochemical attributes (photosynthetic pigment, ion percentage, antioxidant solutes, and organic osmolytes). The maximum EO yield was obtained by 250 mg L −1 sodium metasilicate (Si) under mild drought. Cell organelles exhibited a different degree of malformation and lyse under severe drought; conversely, application of Si forms nullify the abovementioned injuries caused by drought. In conclusion, application of 250 mg L −1 Si improved drought tolerance in sweet basil herb and EO yield by accelerating their antioxidant system, osmoregulation, and maintaining organelles ultrastructure that induced herb growth and EO yield.

中文翻译：

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甜罗勒生长、生理和超微结构改性以及缺水和硅形式处理下的氧化防御系统

目前的调查旨在评估硅形式对甜罗勒 (Ocimum basilicum L.) 生物量和精油 (EO) 生产的作用，以及不同灌溉制度下的一些生理和超微结构改变。干旱显着降低植物生长、光合色素、离子、相对含水量、过氧化氢酶活性和 EO 产量，同时增加有机和抗氧化溶质浓度、EO 百分比、过氧化物酶活性和氧化损伤标准（过氧化氢、脂质过氧化和膜渗透率百分比）。关于 EO 成分，相对于浇水充足的植物，芳樟醇和甲基胡椒酚是干旱条件下减少的主要成分。在水分充足或干旱的条件下外源施用硅形式可以在一定程度上完全或部分补偿甜罗勒植物的发育和生化属性（光合色素、离子百分比、抗氧化溶质和有机渗透物）。在轻度干旱下，通过 250 mg L -1 偏硅酸钠 (Si) 获得最大 EO 产量。细胞器在严重干旱下表现出不同程度的畸形和溶解；相反，Si 形式的应用可以消除上述干旱造成的伤害。总之，通过加速其抗氧化系统、渗透调节和维持诱导草本植物生长和 EO 产量的细胞器超微结构，250 mg L -1 Si 的应用提高了甜罗勒草本植物的耐旱性和 EO 产量。