Salinity stress reduces growth and yield productivity of most crop plants. Potentiality of kinetin (Kn) and epi-brassinolide (EBL), either individually or combinedly in preventing the salinity (100 mM NaCl) stress mediated oxidative damage and photosynthetic inhibition was studied in Solanum lycopersicum. Combined application of Kn and EBL imparted much prominent impact on the growth, photosynthesis and metabolism of antioxidants, osmolytes and secondary metabolites. Synthesis of chlorophylls and carotenoids increased and the photosynthetic parameters like stomatal conductance, intercellular CO2 concentration and net photosynthesis were significantly improved due to application of Kn and EBL. Photosystem II functioning (Fv/Fm), photochemical quenching and electron transport rate (ETR) improved significantly in Kn and EBL treated plants imparting significant decline in salinity induced non-photochemical quenching. Exogenous Kn and EBL effectively prevented the oxidative damage by significantly declining the generation of hydrogen peroxide and superoxide under saline and non-saline conditions as reflected in lowered lipid peroxidation and electrolyte leakage. Reduced oxidative damage in Kn and EBL treated plants was accompanied down-regulation of protease and lipoxygenase concomitant with up-regulation of the antioxidant system and the accumulation of compatible osmolytes. Treatment of Kn and EBL proved effective in enhancing the contents of redox homeostasis, ascorbic acid and reduced glutathione, and the secondary metabolites assisting the enzymatic antioxidant system in combating the salinity stress efficiently. Results suggest that combined application of Kn and EBL regulate growth and photosynthesis in tomato more effectively than their individual application through a probable regulatory crosstalk mechanism.

中文翻译：

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油菜素甾醇和激动素的共同作用通过调节抗氧化剂和渗透压代谢来减轻番茄中的盐分胁迫。

盐分胁迫会降低大多数农作物的生长和单产。在番茄茄中研究了激动素（Kn）和表油菜素内酯（EBL）在预防盐度（100 mM NaCl）胁迫介导的氧化损伤和光合作用抑制中的单独或组合潜力。Kn和EBL的联合使用对抗氧化剂，渗透液和次生代谢产物的生长，光合作用和代谢产生了显着影响。由于施用了Kn和EBL，叶绿素和类胡萝卜素的合成增加，气孔导度，细胞间CO2浓度和净光合作用等光合参数得到显着改善。Photosystem II运行（Fv / Fm），在Kn和EBL处理的植物中，光化学猝灭和电子传输速率（ETR）显着提高，使盐度诱导的非光化学猝灭显着下降。外源性Kn和EBL通过显着降低在盐水和非盐条件下的过氧化氢和超氧化物的生成，有效地防止了氧化损伤，这反映在脂质过氧化和电解质泄漏的降低上。在Kn和EBL处理的植物中，氧化损伤的减少与蛋白酶和脂氧合酶的下调，抗氧化剂系统的上调以及相容性渗透物的积累有关。事实证明，Kn和EBL的处理可有效提高氧化还原稳态，抗坏血酸和减少谷胱甘肽的含量，次生代谢产物可帮助酶促抗氧化系统有效地对抗盐分胁迫。结果表明，通过可能的调节串扰机制，钾和EBL的组合施用比单独施用更有效地调节番茄的生长和光合作用。