Critical Leaf Magnesium Concentrations for Adequate Photosynthate Production of Soilless Cultured Cherry Tomato—Interaction with Potassium

Abstract

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 by 22.6–78.1% 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.

Response and efficiency of magnesium fertilizer application in soybean (Glycine max) and sunflower (Helianthus annuus)

“…The K:Mg accumulation ratio with excessive Mg application reduced plant growth, which may have been due to antagonism between the two elements when an imbalance was created. This phenomenon has been previously reported in cherry tomato [29] and pumelo [32]. Therefore, an unbalanced supply of Mg and K is not desirable because it affects plant growth, quality, and the distribution of nutrients across the plant [1].…”

“…Mg fertilizer application enhanced Mg uptake in plants as well as the accumulation of other nutrients. Similarly, Mg application has been observed to promote N and P accumulation in rapeseed [25] and K and Ca uptake in cherry tomato (Lycopersicon esculentum) [29]. The application of Mg at a rate of 50 and 100 mg Mg/kg presented a K:Mg accumulation ratio of approximately 3:1, which has been demonstrated to be suitable for plant growth.…”

How does soil nutritional stress limit restoration in the Amazon?

“…3), consequently its deficiency is directly related to the decrease in photosynthetic rates (Cakmak and Kirkby 2008). However, excess Mg may inhibit the transport of K of cytosol (Guan et al 2020), a study conducted with Hevea brasiliensis seedlings found a reduction in chlorophyll content and approximately 20% reduction in chloroplast length (Xue et al 2019). Regarding micronutrients, the absence of iron (Fe) interferes with metabolic processes, hormonal regulation, and enzymatic reactions (Krohling et al 2016).…”

Unraveling the Tolerance of Moringa oleifera to Excess K through Increased N Absorption and Mg Use Efficiency

“…Research often indicates that increased K in crops may interact with other nutrients such as Mg and Ca [7][8][9], decreasing the uptake of these elements depending on the species. This situation impairs the growth of crops such as maize, potato, sugarcane, and cherry tomato [10][11][12][13]. Excess K is more likely to have an antagonistic effect with cations, but a synergistic effect can also take place.…”