Volume 49 Number 3

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

Chakkrit Poonpakdee^a,*, Khabele Z. Ntlopo^b, Jumpen Onthong^a, Khwunta Khawmee^a, Yao-Tung Lin^c,d

 
ABSTRACT:      Magnesium (Mg) is essential in plant biochemical processes. However, tropical Ultisols soils generally contain low levels of Mg. Mg is often neglected in fertilization programs, and proper application rates have not yet been established. This study was designed to assess the influence of Mg application on soybean (Glycine max) and sunflower (Helianthus annuus) with regard to biomass accumulation, Mg efficiency traits, and the optimal accumulation ratio of K:Mg in the plant. A low extractable Mg (12.20 mg/kg) soil was used to evaluate the plant responses to Mg application at 0, 50, 100, and 200 mg Mg/kg in a pot experiment. The results showed that Mg fertilizer application at the 50 mg Mg/kg level improved biomass by 25% and 119% in soybean and sunflower, respectively, exhibiting a K:Mg accumulation ratio of 3:1 in plants. The Mg fertilizer application at 50?100 mg Mg/kg enhanced plant growth and nutrient uptake and elevated the leaf Mg concentration above the critical level. In contrast, excessive Mg fertilizer application (200 mg Mg/kg) suppressed biomass and nutrient accumulation. Therefore, a suitable Mg fertilizer application for optimum plant growth and high efficiency factors can be recommended at 50?100 mg Mg/kg for soybean and sunflower cultivated in tropical Ultisols soils containing low extractable Mg.

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* Corresponding author, E-mail: chakkrit.p@psu.ac.th

Received 16 Apr 2022, Accepted 11 Mar 2023