Rhizosphere phosphatase enzyme activities and secondary metabolites in plants as affected by the supply of Rhizobium, lime and molybdenum in Phaseolus vulgaris L.

Abstract

Knowledge about changes of enzyme activities in the rhizosphere soil and secondary metabolites in Phaseolus vulgaris L. plant is necessary to understand especially during the management of acid soils. A glasshouse and field experiments were therefore conducted to investigate the effects of applying or not applying Rhizobium inoculation, molybdenum (0, 6, 12 g kg-1 seed) and lime (0, 2, 3 t ha-1) on the rhizosphere enzymes activities, flavonoids and anthocyanins concentration in P. vulgaris L. Glasshouse and field experiments indicated that Rhizobium inoculation, Mo at 12 g kg-1 seed and lime at 3 t ha-1 supply significantly showed lowest acid and alkaline phosphatase activities and flavonoids and anthocyanins concentration compared with control treatments which showed highest values. The lower rhizosphere activities of these enzymes and plants’ secondary metabolites with Rhizobium and greater supply of Mo and lime suggest less stress for mineral elements essential for plant growth such as N, Ca, and Mo compared with control. Furthermore, the data suggest that the lower the stress for mineral elements in the rhizosphere soils of legumes such as P. vulgaris L. the lower the phosphatase activities and plants’ flavonoids and anthocyanins concentrations.