Magnesium Fertilizer Application and Soil Warming Improves Magnesium Absorption and Yield of Tomatoes in Greenhouse

Background: Magnesium (Mg) is an essential macronutrient that plays an important role in numerous physiological and biochemical processes in plants. However, Mg deficiency is common worldwide, especially in greenhouse vegetable systems, due to the overuse or misuse of fertilizers. This study aimed to investigate different Mg application strategies for alleviating Mg deficiency in tomatoes grown in a greenhouse vegetable system. Methods: : Six field treatments were used: the farmer conventional fertilization practice (CK), CK + soil application of Mg fertilizer (MgS), CK + foliar spray of Mg fertilizer (MgF), CK + the combination of soil and foliar spray of Mg fertilizer (MgSF), CK + soil warming (T), and MgSF + soil warming (MgSFT). Results: : The results showed that the foliar spray of Mg fertilizer treatments (MgF, MgSF, and MgSFT) increased the total Mg uptake and Mg content of functional leaves in both winter-spring and autumn-winter seasons. Soil warming treatments (T and MgSFT) were also beneficial for Mg uptake and chlorophyll biosynthesis compared with no-warming treatments (CK and MgSF), especially in the autumn-winter season. Additionally, Mg fertilizer application and soil warming increased tomato yields; the MgSFT treatment had the highest increase in yields compared with the CK treatment. Conclusion: Therefore, foliar Mg fertilizer application combined with soil warming, while considering seasonal variation, is feasible for reducing Mg deficiency in tomatoes under greenhouse vegetable systems.