Detection of metabolites in rhizosphere of soybean under different status of soil potassium

ABSTRACT Nutrient status of plant affects root exudates of plant. Little is known about effect of potassium status on root exudation. Objective of this study was to identify metabolites in rhizosphere soil of soybean under different potassium conditions. Two soybean cultivars (Satonohohoemi (SAT) and Tachinagaha (TAC)) were grown in soil culture under low (K0, without potassium fertilizer) and normal (K2, 0.42 g K kg−1) soil potassium status. Soil solutions were collected at 15 and 25 DAS. Metabolites in soil solution were detected by CE-TOF MS. Low potassium tolerance was higher in SAT than TAC. Shoot and root K concentration in SAT was lower in K0 than that in K2. Forty-seven metabolites were detected in rhizosphere soil solution of SAT, TAC and without plant. Low K condition increased 6 and 3 metabolites concentration in soil solution without plant and 2 and 4 metabolites concentration with SAT and 2 and 1 metabolites concentration with TAC, at 15 and 25 DAS, respectively. Low K condition decreased 1 and 1 metabolites concentration in soil solution without plant and 6 and 6 metabolites concentration with SAT and 0 and 2 metabolites concentration with TAC, at 15 and 25 DAS, respectively. Increased and decreased metabolites were different between SAT and TAC. These results suggest that K status affect metabolites in root exudate and rhizosphere microbes of soybean and there is cultivar difference in these metabolites.