Net ammonium and nitrate fluxes in wheat roots under different environmental conditions as assessed by scanning ion-selective electrode technique

Wheat is one of the most important food crops in the world, its availability affects global food security. In this study, we investigated variations in NH(4)(+) and NO(3)(-) fluxes in the fine roots of wheat using a scanning ion-selective electrode technique in the presence of different nitrogen (N) forms, N concentrations, and pH levels as well as under water stress. Our results show that the fine roots of wheat demonstrated maximum NH(4)(+) and NO(3)(−) influxes at 20 mm and 25 mm from the root tip, respectively. The maximal net NH(4)(+) and NO(3)(−) influxes were observed at pH 6.2 in the presence of a 1/4 N solution. We observed N efflux in two different cultivars following the exposure of roots to a 10% PEG-6000 solution. Furthermore, the drought-tolerant cultivar generally performed better than the drought-intolerant cultivar. Net NH(4)(+) and NO(3)(−) fluxes may be determined by plant growth status, but environmental conditions can also affect the magnitude and direction of N flux. Interestingly, we found that NO(3)(−) was more sensitive to environmental changes than NH(4)(+). Our results may be used to guide future hydroponic experiments in wheat as well as to aid in the development of effective fertilisation protocols for this crop.