Magnesium Foliar Supplementation Increases Grain Yield of Soybean and Maize by Improving Photosynthetic Carbon Metabolism and Antioxidant Metabolism.

Vitor Alves Rodrigues,Tamara Thaís Mundt,Ariani Garcia,Juliano Carlos Calonego,João William Bossolani,Carlos Alexandre Costa Crusciol,José Roberto Portugal,Luiz Gustavo Moretti,Romulo Pisa Lollato,Sirlene Lopes De Oliveira

doi:10.3390/plants10040797

Vitor Alves Rodrigues, Tamara Thaís Mundt + Show 8 more

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https://doi.org/10.3390/plants10040797

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Abstract

(1) Background: The aim of this study was to explore whether supplementary magnesium (Mg) foliar fertilization to soybean and maize crops established in a soil without Mg limitation can improve the gas exchange and Rubisco activity, as well as improve antioxidant metabolism, converting higher plant metabolism into grain yield. (2) Methods: Here, we tested foliar Mg supplementation in soybean followed by maize. Nutritional status of plants, photosynthesis, PEPcase and Rubisco activity, sugar concentration on leaves, oxidative stress, antioxidant metabolism, and finally the crops grain yields were determined. (3) Results: Our results demonstrated that foliar Mg supplementation increased the net photosynthetic rate and stomatal conductance, and reduced the sub-stomatal CO2 concentration and leaf transpiration by measuring in light-saturated conditions. The improvement in photosynthesis (gas exchange and Rubisco activity) lead to an increase in the concentration of sugar in the leaves before grain filling. In addition, we also confirmed that foliar Mg fertilization can improve anti-oxidant metabolism, thereby reducing the environmental stress that plants face during their crop cycle in tropical field conditions. (4) Conclusions: Our research brings the new glimpse of foliar Mg fertilization as a strategy to increase the metabolism of crops, resulting in increased grain yields. This type of biological strategy could be encouraged for wide utilization in cropping systems.

Highlights

Magnesium (Mg) is present in many essentials physiological processes and play crucial functions on photosynthesis, photoprotection, and on the carbohydrate partitioning within plants [1]
In the second soybean-growing season, the most striking dry spell occurred during the vegetative period, with a less intense second dry spell occurring between the end of R2 and the end of R4
This increased Mg concentration may improve growth parameters due to the important roles that Mg plays in plant metabolism, especially those related to chlorophyll biosynthesis, photosynthesis, and carbon assimilation, in addition to activating numerous key chloroplast enzymes [21,23,27]

Summary

Introduction

Magnesium (Mg) is present in many essentials physiological processes and play crucial functions on photosynthesis, photoprotection, and on the carbohydrate partitioning within plants [1]. Several studies have shown that Mg is critically involved in the phloem loading of sucrose and carbohydrate partitioning between source and sink tissues [4]. The phloem loading of sucrose is an active process catalyzed by a proton gradient and an H+/sucrose co-transporter, and for its proper functioning, great concentration of ATP-Mg is necessary. The coordination between production and use of photoassimilates for metabolic activity is key for the maintenance of the photosynthetic process and growth by plants [8]. The consumption of photoassimilates by the sink organs activates a positive feedback mechanism that stimulates the production of sugar by the leaves, and photosynthesis activity [9]

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