Abstract The purpose of this study was to evaluate the role of proline in relieving the growth inhibition of lettuce grown under low potassium conditions. Lettuce was hydroponically grown in a half-strength Enshi formula nutrient solution containing 2 mM K+ and treated with exogenous prolines (0.5, 1.0, 1.5, and 2.0 mM). The results revealed that exogenous proline applications with 1.0 and 1.5 mM alleviated oxidative damage in lettuce leaves, as demonstrated by lower lipid peroxidation and hydrogen peroxide concentrations, together with an increased activity of antioxidant enzymes. Additionally, the application of 1.0 or 1.5 mM proline enhanced the levels of proline, soluble sugars, and ascorbic acid in leaves compared with lettuce grown under low potassium condition. The growth analysis results suggest that addition of 1.0 and 1.5 mM exogenous proline increased the relative growth rate, mainly by increasing the leaf area ratio. To a lesser extent, this growth was caused by an increase in the net assimilation rate. We proposed that the application of proline in certain concentrations could increase the yield and quality of lettuce through regulating the biochemical process of plants under low potassium conditions.

中文翻译：

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外源脯氨酸提高低钾生菜的生长和产量

摘要 本研究的目的是评估脯氨酸在缓解低钾条件下生长的生菜生长抑制中的作用。生菜在含有 2 mM K+ 的半强度恩施配方营养液中水培生长，并用外源脯氨酸（0.5、1.0、1.5 和 2.0 mM）处理。结果表明，外源性脯氨酸浓度为 1.0 和 1.5 mM 可减轻生菜叶片的氧化损伤，这可以通过降低脂质过氧化和过氧化氢浓度以及增加抗氧化酶的活性来证明。此外，与在低钾条件下生长的生菜相比，施用 1.0 或 1.5 mM 脯氨酸可提高叶片中脯氨酸、可溶性糖和抗坏血酸的含量。增长分析结果表明 1.0 和 1. 5 mM 外源脯氨酸增加了相对生长速率，主要是通过增加叶面积比。在较小程度上，这种增长是由净同化率的增加引起的。我们提出在低钾条件下施用一定浓度的脯氨酸可以通过调节植物的生化过程来提高生菜的产量和品质。