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

Takuji Ohyama (), Koyo Takayama, Ayaka Akagi, Akihiro Saito, Kyoko Higuchi and Takashi Sato
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Takuji Ohyama: Department of Agricultural Chemistry, Faculty of Applied Biosciences, Tokyo University of Agriculture, Tokyo 156-8502, Japan
Koyo Takayama: Department of Agricultural Chemistry, Faculty of Applied Biosciences, Tokyo University of Agriculture, Tokyo 156-8502, Japan
Ayaka Akagi: Department of Agricultural Chemistry, Faculty of Applied Biosciences, Tokyo University of Agriculture, Tokyo 156-8502, Japan
Akihiro Saito: Department of Agricultural Chemistry, Faculty of Applied Biosciences, Tokyo University of Agriculture, Tokyo 156-8502, Japan
Kyoko Higuchi: Department of Agricultural Chemistry, Faculty of Applied Biosciences, Tokyo University of Agriculture, Tokyo 156-8502, Japan
Takashi Sato: Faculty of Bioresource Sciences, Akita Prefectural University, Akita 010-0195, Japan

Agriculture, 2023, vol. 13, issue 3, 1-14

Abstract: Soybean plants can grow by solely depending on fixed N 2 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 root growth and nutrient absorption. Therefore, we prepared a new N-free culture solution characterized by less pH fluctuation due to the addition of potassium bicarbonate. A total of 1–2 mM sodium bicarbonate optimized the pH between 6 and 7. However, the solution pH increased to 8–9 during soybean cultivation when 5–20 mM of sodium bicarbonate was applied. The addition of potassium bicarbonate did not affect the dry weight of each organ. The evapotranspiration rate of the plants with bicarbonate on the 37th day after planting was higher than that of the control without bicarbonate. When the K 2 SO 4 was replaced by KHCO 3 , the pH just after preparation ranged between 6.3 and 6.5, while that after cultivation for two days ranged frp, about 6.1 to 6.5. It was found that more than half of the bicarbonate remained in the culture solution after 3 days of cultivation. The optimum P concentrations for the modified culture solution were found to be 50 and 100 μM, while the P concentrations over 150 μM reduced the plant growth and led to yellowing in the lower leaves.

Keywords: culture solution; pH; potassium bicarbonate; soybean (search for similar items in EconPapers)
JEL-codes: Q1 Q10 Q11 Q12 Q13 Q14 Q15 Q16 Q17 Q18 (search for similar items in EconPapers)
Date: 2023
References: View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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