Intact roots and transversal root segments of sweet-potato (Ipomea batatas L. Lam) were partially or completely submerged in water. In partially submerged roots less than 10% of the dermal surface remained exposed to air through a vent. Internal atmosphere pressure in partially submerged roots remained a few millimeters bellow the atmospheric pressure, while a much larger and nearly linear pressure reduction occurred in completely submerged roots. This linear phase caused a pressure reduction larger than 1m of water column. After that, the pressure started to rise slowly. The observed pressure reduction was smaller than the one observed in the constant pressure manometry procedure where the roots were sealed with epoxy resin, which precluded any water infiltration and changes of root volume. Partially submerged intact roots and segments were less subject to intercellular water infiltration than the completely submerged ones. The mass increase of submerged intact roots was caused mainly by water absorption, a process which is known to exclude molecules with a size larger than a few nanometers. In transversely segmented roots most water entered by intercellular volume infiltration, which may introduce fungi spores and bacteria and other particles inside the damaged organ.
Ipomea batatas; intercellular volume; sanitation; water absorption; vegetable