Fig. 1. (A) Mean dry mass of above-ground (stems, leaves, flowers/berries) and below-ground (roots, tubers, stolons) plant parts measured in potato plants grown under glass. The broken line indicates the switch in dry-matter partitioning (see text for explanation). Values are the means ± S.E.M. of ten plants. (B) Ratio of carbon to nitrogen (C:N) (as percentage of dry mass) in dried leaf tissue and the molar ratio of sucrose to amino acid (sucrose:amino acid) in leaflet phloem exudates sampled from potato plants grown under glass. Values are the means ± S.E.M., N=9-10.