Figure 1.

Hypothetical distribution of mucilage and water in the rhizosphere during a drying and wetting cycle. (A) Mucilage is exuded at the root tips and diffuses through the soil matrix. (B) As roots take up water and the soil becomes dry, mucilage dehydrates and shrinks around the root and the soil particle near the root (the rhizosphere). As the soil dries and mucilage becomes old, mucilage becomes water repellent and stiff. (C) After irrigation, old mucilage rewets slowly and the rhizosphere remains temporarily dry, possibly limiting the local water uptake. Freshly exuded mucilage covering the root tip is expected to rewet quickly. Water uptake might increase at the root apical segments.