Fig. 8

Schematic comparisons between barley and poplar roots cultivated in hydroponic control conditions. Figure a is based on data from [40] and the 12-days-old barley plants were cultivated in the same laboratory under identical environmental conditions as the poplar plants grown in hydroponic setups for 5 weeks (b). In the apical zone A (0–25%; 0–27.5% relative root length), only Casparian bands and no suberin lamellae were developed. Zone B (25–50%; 27.5–100%) was characterized by a patchy suberization of the endodermis. In contrast to barley seminal roots (50–100%), no basal zone C exhibiting full suberization of the endodermis could be identified in poplar adventitious roots. For simplification, only main roots without lateral roots are shown. Red dots indicate Casparian bands, yellow lines indicate suberin lamellae