Nitrate induction and physiological responses of two maize lines differing in nitrogen use efficiency: effects on N availability, microbial diversity and enzyme activity in the rhizosphere

Aim The rate of nitrate (NO3−) uptake and changes in rhizosphere properties were studied growing seedlings of two maize inbred lines differing in nitrogen use efficiency (NUE) in rhizoboxes. Results Changes in NO3− uptake rates occurred in re- sponse to anion addition (induction) in seedlings grown both in hydroponic culture and in soil in rhizoboxes. The characterization of root exudate composition showed a line-specific metabolite profile, which was also affected by NO3− availability. The induction affect- ed respiration, nitrification, ammonification and enzyme activities of the rhizosphere. Furthermore, the composi- tion of rhizosphere bacterial communities of the two maize lines differed suggesting the selective capacity of plants. Conclusions Overall, results showed a strong and fast modification of rhizospheric soil properties in response to physiological changes in plants caused by fluctuating NO3− availability.