The experiment that is used to identify the tissue through which food is transported is Girdling experiment.
In this experiment, a ring of bark (phloem) is removed from the wood by a technique known as girdling.
Since the woody xylem part present on the inner side remains intact, water and nutrient reach the leaves.
but after photosynthesis, food is not transported to other parts below the girdle since the phloem part is removed.
So it is observed that there is an accumulation of the food/sugar just above the girdle region.
This experiment shows that the phloem tissue aids food transport.