Development of an N-Free Culture Solution for Cultivation of Nodulated Soybean with Less pH Fluctuation by the Addition of Potassium Bicarbonate

Soybean plants can grow by solely depending on fixed N2 through their root nodules, a symbiotic organ with rhizobia. In this study, when nodulated soybeans were cultivated using hydroponics and an N-free culture solution, the pH rapidly decreased to 4.0, which may be harmful for growth nutrient absorption. Therefore, we prepared new solution characterized less fluctuation due addition of potassium bicarbonate. A total 1–2 mM sodium bicarbonate optimized between 6 7. However, increased 8–9 during soybean cultivation 5–20 was applied. The did not affect dry weight each organ. evapotranspiration rate 37th day after planting higher than that control without When K2SO4 replaced KHCO3, just preparation ranged 6.3 6.5, while two days frp, about 6.1 6.5. It found more half remained in 3 cultivation. optimum P concentrations modified 50 100 μM, over 150 μM reduced plant led yellowing lower leaves.