Maintenance and hysteresis of soil-root interface water potential of cherry-plum [Prunus cerasifera] in response to soil dehydration and rehydration
1999
Xu, H.L. (International Nature Farming Research Center, Hata, Nagano (Japan)) | Caron, J. | Bernier, P.Y. | Umemura, H. | Gauthier, L. | Gosselin, A.
Soil-root interface water potential (psis.r) of a dry soil indicates the water status at the interface between the soil and the root, but it cannot be easily measured although it is proposed as an appropriate indication of plant water stress. Using an equation of Ohm's analog, we estimated psis.r and examined the maintenance and hysteresis of psis.r as well as xylem water potential (psiX) and transpiration rate (Elambda) in response to soil dehydration and rehydration for cherry-plum plants (Prunus x cistena) grown in three artificial soil mixes. These mixes were made of composted bark, peat, and sand (Mix-1), peat, bark, sand, and compost (Mix-2), and peat, sawdust, and sand (Mix-3). When water was withheld and the soil matric potential (psim) was lowered, plants grown in Mix-2 maintained higher psis.r as well as higher psiX. However, when the soil mix was rehydrated, psis.r was always lower during the re-wetting than during the drying cycles. The relationship between psim and psis.r showed a strong hysteresis-like behavior. Hysteresis was the largest in Mix-2 and the smallest in Mix-3. Hysteresis of psiX or Elambda showed a similar trend to that of psis.r. The differences among soil mixes in hysteresis of psis.r might be related to the unsaturated hydraulic conductivity of substrates
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