Inoculation reduces nitrate accumulation and increases growth and nutrient accumulation in hydroponic arugula

Abstract

Inoculation with plant growth-promoting bacteria (PGPBs) has remarkably increased yield and nutrient uptake of crop plants. The objective of this study was to evaluate the effect of bacterial inoculation with Azospirillum brasilense, Bacillus subtilis and Pseudomonas fluorescens on growth, accumulation of nutrients as well as N[sbnd]NH4+ and N[sbnd]NO3− in hydroponic arugula plants. The research was carried out in a nutrient film technique (NFT) system and designed in randomized blocks with 5 replications. The treatments consisted of inoculation with A. brasilense, B. subtilis and P. fluorescens via nutrient solution at a dose of 0.1 mL L−1 and without inoculation treatment. Inoculation with P. fluorescens promoted N[sbnd]NH4+ accumulation in shoots and roots by 311% and 119% respectively as compared to non-inoculated plants. Inoculations with A. brasilense, B. subtilis and P. fluorescens reduced N[sbnd]NO3− accumulation in shoots and roots by18 and 14% as compared to without inoculation treatments. Fresh and dry mass of roots, root volume and leaf chlorophyll index were increased with inoculation of P. fluorescens and being considered the most suitable inoculant for hydroponic arugula cultivation. Inoculation with A. brasilense, P. fluorescens and B. subtilis reduced shoot N[sbnd]NO3− accumulation, thus benefiting human health.