The Role of Metal Ions in Protein and Fatty Acids Biosynthesis in Soybean under Micronutrients Application to Soil

The present study is part of our ongoing investigation to study the role of trace elements on soybean seed composition (protein, oil, and fatty acids). This study was conducted to study the effects of five trace elements (Mn, Cu, Zn, Mo, B). The treatments of Mn, Cu, Zn, Mo, and B were chlorides, except Mo as oxide, and B as boric acid. The treatments were Mn, Cu, Zn, Mo, and B alone and in combination with the chelating agent citric acid (CA), for example Mn + CA, Cu + CA, and Zn + CA. Soybean cultivar (Bolivar with maturity group V) was grown in a repeated greenhouse experiment in a randomized complete block design. The compounds were applied to three-week-old soybean plants at V3 (vegetative) and at R3 (beginning of seed-pod initiation) stages. The plants were allowed to grow until maturity under greenhouse conditions. The harvested seeds were analyzed for mineral, protein, and fatty acid contents. Results showed that Mn, Cu, and B treatments increased seed protein, while Zn, Mo, Cu + CA, and B + CA decreased the protein. Treatments of Zn, Mo, CA, Cu + CA, Zn + CA, Mo + CA, and B + CA increased the oil. Treatments of Mn and Cu decreased the oil. The Cu and B treatments increased oleic acid by 8.0% and 7.4%, respectively for Cu and B. Treatments of Mn, Mo, CA, and Mn + CA, Cu + CA, Zn + CA, Mo + CA, and B + CA decreased oleic acid by 0.6% to 14.4%. Treatments of Cu, Zn, Mo, B, CA, Mn and their combination with CA increased linoleic acid by 1.3% to 6.5%. Our goal was to identify the trace elements that would make desirable alteration in the seed composition qualities.