Figure 6.

Estimated evolution of the k_r in main axes of the maize root system derived from Doussan et al. (1998). Top, k_r as a function of distance from the maize root tip. Bottom, the illustrations depict our assumption of the evolution of main apoplastic barriers based on Enstone and Peterson (2005). The different lines represent different level of apoplastic barriers. 1: Endodermal Casparian strip (dashed blue); 2: Endodermal suberization (red); 3: Endodermis full suberization and exodermal Casparian strip (dashed green).