Benzoic Acid Influenced Phaseolus vulgaris L. Rhizospheric Soil Fungal Community and Crop Quality

Abstract

The exudation of allelochemicals by root of legumes can lead to soil fatigue through the accumulation of the allelochemicals in the rhizosphere following repeated release and slow decomposition rates by microbes inhabiting the soil. Phaseolus vulgaris L. exuded benzoic acid, which is one of the key phenolic compounds and is said to have strong phytotoxic effects. The purpose of the study was to assess the impact of benzoic acid on the growth of P. vulgaris and yield, as well as to determine the influence of benzoic acid on the population of rhizospheric fungi. Sandyloam and clay loamy soils that were sprayed with benzoic acid at 0.15, 0.25, 0.5 and 1.0 mmol g-1 soil were used to grow plants. The percent germinating, biomass, the number of pods, and yield of the seed were determined and the rhizospheric fungi were determined by using standard culture methods. The findings indicated that the growth of plants and their yield were inhibited by benzoic acid in a concentration-dependent way, and the maximum inhibition was observed when the concentration was 1.0 µmolg-1. The abundance of culturable fungi reduced substantially with benzoic acid concentration; whereas intermediate concentrations promoted the proliferation of certain fungi, including Fusarium solani and Aspergillus niger. These results prove that the presence of benzoic acid in the rhizosphere negatively impacts plant functions and fungal communities of the soil. The allelochemical accumulation in the continuous cropping systems is hence an issue of concern in terms of the balance of microbes of the soil and enhancing crop yield.