Magnesium Fertilizer Application and Soil Warming Increases Tomato Yield by Increasing Magnesium Uptake under PE-Film Covered Greenhouse

Abstract

Magnesium (Mg) 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 investigated the effects of different Mg application strategies in alleviating Mg deficiency of tomatoes in PE-film covered greenhouse. Six field treatments were used: conventional fertilization practice (C), conventional fertilization + soil warming (CW), conventional fertilization + Mg applied to soil (C + MgS), conventional fertilization + Mg applied as foliar application (C + MgF), conventional fertilization + Mg applied to soil and foliar application (C + MgSF), and conventional fertilization + Mg applied to soil and foliar application with soil warming (C + MgSFW). Foliar spray of Mg fertilizer (C + MgF, C + MgSF, and C + MgSFW) increased the total Mg uptake and Mg content of functional leaves in both winter-spring and autumn-winter seasons. Soil warming treatments (CW and C + MgSFW) were also beneficial for Mg uptake and chlorophyll biosynthesis compared with no-warming treatments (C and C + MgSF), especially in autumn-winter season. Additionally, Mg fertilizer application and soil warming increased tomato yields; the C + MgSFW treatment had the highest increase in yields compared with the C treatment. Therefore, foliar Mg fertilizer application combined with soil warming, while considering seasonal variation, is feasible for reducing Mg deficiency in tomatoes under PE-film covered greenhouse vegetable systems.