The influence of stage of vegetative flush development on NH4NO3-N uptake and carbon and nitrogen partitioning was evaluated in two-year-old 'Climax' rabbiteye blueberries using dual labeling with 15N and14C. Plants were grown in sand and fertilized with a modified Hoagland's solution. Plants were pruned to induce three stages of vegetative development: flush initiation, mid -flush, and flush maturity.
Total nitrogen uptake did not differ for the different stages of growth. However, N allocation to leaves was greatest at mid-flush, possibly due to higher transpiration rates of developing leaves. Total 14C partitioning to roots was reduced at mid-flush, compared to the other growth stages, reflecting the increased demand for carbon by growing shoots. Although less carbon was allocated to roots at mid-flush,this did not limit N uptake.