Magnesium (Mg) is essential to many plant physiological and biochemical processes; however, understanding how Mg nutrition quantitatively affects the production, partitioning, and utilization of photoassimilates is still lacking, especially in soilless culture systems. We focused on the roles of Mg in yield formation and interactions with potassium (K) nutrition of cherry tomato. Cherry tomato yield, photosynthetic parameters, dry matter weight, and K, Mg, and calcium (Ca) uptake were investigated in two soilless experiments with seven Mg levels and five K levels. The results showed that low (<1 mM) and high (>4 mM) Mg supply limited cherry tomato yield by decreasing dry matter accumulation by22.6–78.1% and harvest index by 13.9–40.7%. The critical leaf Mg concentrations required for adequate photosynthate production in the first and second harvest periods were 4.67 and 5.52 g·kg⁻¹, respectively. However, over-supply of Mg reduced leaf K and Ca concentrations and limited plant uptake of K and Ca. Moreover, adjusting K concentrations in solution could influence plant Mg functions in photosynthesis and, therefore, cherry tomato growth. Overall, balanced Mg and K application increased Mg, K, and Ca uptake, as well as Mg concentrations in leaves, which could maintain a sustainable photosynthetic rate and plant dry matter formation.

中文翻译：

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无土栽培樱桃番茄光合产物产量的临界叶镁浓度－与钾的相互作用

镁对于许多植物的生理和生化过程至关重要。但是，仍然缺乏对镁营养如何定量影响光同化产物的生产，分配和利用的了解，尤其是在无土栽培系统中。我们专注于镁在樱桃番茄产量形成中的作用以及与钾（K）营养的相互作用。樱桃番茄的产量，光合作用参数，干物质重量以及钾，镁和钙（Ca）的吸收在两个无土的实验中进行了调查，其中七个镁水平和五个钾水平。结果表明，低（<1 mM）和高（> 4 mM）的镁供应限制了樱桃番茄的产量，使干物质积累降低了22.6–78.1％，收获指数降低了13.9–40.7％。^-1。然而，镁的过量供应降低了叶片中钾和钙的含量，限制了植物对钾和钙的吸收。此外，调节溶液中钾的浓度可能会影响植物Mg在光合作用中的功能，从而影响樱桃番茄的生长。总体而言，平衡施用Mg和K可以增加Mg，K和Ca的吸收以及叶片中Mg的浓度，从而可以维持可持续的光合作用速率和植物干物质的形成。