Foliar fertilisation of phosphorus (P) is an alternative for reducing the use-efficiency and the environmental threats associated with phosphate-based fertilisers. Moreover, silicon (S) hyperaccumulator species were found to have limited Si accumulation in P-deficient wheat seedlings. Therefore, the present proposal aims to explore synchrotron-based X-ray fluorescence and absorption spectroscopy to evaluate the distribution of P and Si in wheat seedlings cultivated under P-sufficient and P-deficient conditions, as well as to assess the dynamics of foliar P absorption when supplied either as hygroscopic or non-hygroscopic P-salts. The results will help to establish a link between P and Si nutrition on stress tolerance in plants and optimise P- P-based fertilisers.