Does subjecting plants to water stress enhance biological nitrification inhibition potential of rice?

Background and aims Biological nitrification inhibition (BNI) is a trait that could improve nitrogen-use efficiency of a crop. We studied varietal differences in BNI potential of rice at the vegetative phase when plants were subjected to water stress. Methods We obtained water-soluble root exudates (RE) and water-extracts of crushed root tissues (RT) from two-week-old seedlings of five rice cultivars grown continuously under adequate water or under water stress and assessed their ability to suppress the activity of Nitrosomonas europaea and the growth of lettuce seedlings. We also investigated how growing rice under continuously saturated (T C ) and unsaturated (T U ) soil moisture conditions affected potential nitrification rate (PNR) and community structure of ammonia-oxidizing bacteria (AOB) in the rhizosphere compared with bulk soil. Results We observed that only RT at ≥ 0.50 mg ml −1 suppressed the activity of N. europaea with significant ( p