PRODJINOTO, H.; Batat, D.; Nir, I.; Menkes, D.; Shenker, M.; Moshelion, M.

waterlogging constrains terrestrial plants by limiting oxygen diffusion in the rhizosphere and altering root-zone physical and chemical properties. However, the extent to which whole-plant responses to waterlogging can be reproduced by oxygen deficiency alone remains unresolved. In tomato (Solanum lycopersicum), waterlogging is commonly associated with adventitious-root formation, yet the functional contribution of these roots to whole-plant water relations has rarely been quantified. Here, we experimentally separated root-zone hypoxia from waterlogging and quantified the contribution of surface-associated adventitious roots to whole-plant transpiration. Using high-resolution gravimetric lysimeters, we monitored transpiration dynamics under two conditions: (i) N2-driven displacement of root-zone O2 under near-field-capacity conditions and (ii) root-zone waterlogging. These measurements were complemented by analyses of soil redox potential and pH, mineral composition, stem anatomy, and genotypic variation among M82, IL11-4, and IL8-1. N2-driven oxygen depletion rapidly reduced rhizosphere O2 concentration and induced a moderate decline in redox potential, accompanied by changes in rhizosphere chemistry and mineral relations. Whole-plant transpiration, however, declined only progressively over several days. Under waterlogging, transpiration declined rapidly in all genotypes, with strong genotype dependence. A transient partial recovery coincided with the appearance of adventitious roots at the soil surface and was followed by renewed decline after drainage. Quantitative analysis indicated that adventitious roots contributed only a limited fraction of daily water uptake, approximately 15% to 20%, which was insufficient to restore pre-waterlogging transpiration or growth. Together, these results show that waterlogging responses were not reproduced by rapid oxygen deprivation alone and that adventitious roots provide limited hydraulic compensation.