Effect of phloem interruption on leaf senescence and nutrient redistribution in wheat (Triticum aestivum)

The phloem of field-grown wheat was interrupted shortly after anthesis by steam-girdling below the ear or below one of the 2 uppermost leaf nodes. Senescence and nutrient remobilisation was delayed in leaves without phloem connection to the ear. Dry matter, phosphorus and potassium accumulation in the ear strongly depended on the number of leaves with an intact phloem to the head. Mobile nutrients were further redistributed within the ear from the glumes to the grains, while calcium increased in all parts. The capacities of sources, sinks and transport systems may contribute to the overall regulation of nutrient fluxes in intact plants.