Phosphorus uptake and partitioning in two durum wheat cultivars with contrasting biomass allocation as affected by different P supply during grain filling

Aims Phosphorus (P) export with harvested grains is a key step of the P cycle in agroecosystems. In wheat, the accumulation of P in grains originates from both exogenous and endogenous P sources. We investigated the effects of different post-anthesis P supply on P partitioning and P remobilization in two durum wheat cultivars with contrasting biomass allocation. Methods Wheat plants were grown on a complete nutrient solution with sufficient P until anthesis. Thereafter, half of the plants were deprived of P and the other half was maintained on the complete nutrient solution. P uptake, allocation, remobilization, and traits related to yield and grain P were determined. Results Modifications of post-anthesis P supply had no effect on grain yield. Grain P concentrations at maturity for deprived P supply ranged from 2.2 to 3.4 mg P g DW- 1. Without P, net P fluxes to grains essentially came from leaves (35%), roots (28%) and stems (17% ). With P, net P fluxes came mainly from post-antheis P uptake. Conclusions Our results suggest that when the P nutrition of durum wheat is limited after anthesis, endogenous P remobilization can sustain grain growth with minor yield penalties if the plants are well supplied during vegetative growth.