Fig. 7.

Proposed model of upward P fluxes in rice plants before (A) and after (B) flowering. Model variations B₁ and B₂ represent the two possible reproductive fluxes enabling P to be loaded into grains, that is either using roots (B₁) or vegetative tissues (B₂) as the main secondary P source. Size of arrows is proportional to the amount of P mobilized by fluxes from sowing to flowering (A) and during grain filling (B) measured in Opt-P treatment of the hydroponic study. Values in italic depict the percentage of ³³P activity in plants 24 h after spiking in Opt-P.