Linking stem diameter variations to sap flow, turgor and water potential in tomato
2010
De Swaef, Tom | Steppe, Kathy
Water status plays an important role for fruit quality and quantity in tomato (Solanum lycopersicum L.). However, determination of the plant water status via measurements of sap flow (FH₂O) or stem diameter (D) cannot be done unambiguously since these variables are influenced by other effectors than the water status. We performed a semi-seasonal and a diurnal analysis of the simultaneous response of FH₂O and D to environmental conditions, which allowed us to distinguish different influences on ΔD such as plant age, fruit load and water status and to reveal close diurnal relationships between FH₂O and ΔD. In addition, an analysis of the diurnal mechanistic link between both variables was done by applying a slightly modified version of a water flow and storage model for trees. Tomato stems, in contrast with trees, seemed to maintain growth while transpiring because a large difference between turgor pressure (Ψp) and the yield threshold (Γ) was maintained. Finally, the simultaneous response of D and FH₂O on irrigation events showed a possibility to detect water shortages.
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