Seasonal trends in hydraulic conductance of field-grown ‘Valencia’ organge trees |
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Authors: | Samuel Moreshet George C Green |
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Institution: | Division of Agricultural Meteorology, ARO, Bet Dagan, Israel;Soil and Irrigation Research Institute, Pretoria, Republic of South Africa |
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Abstract: | Leaf water potential (ψ1), whole tree transpiration (F) and leaf surface conductance (g), together with a number of environmental parameters, were measured from early summer until late winter in a well-watered mature ‘Valencia’ orange (Citrus sinensis (L.) Osb.) orchard during the growing season of 1977/78. F and g showed a seasonal trend, with maximum values reached during the late summer. Tree conductance (Ctree), calculated as the ratio between transpiration and the water potential difference between the wet soil and the sunlit leaves, was found to vary seasonally and showed maximum values during late summer. The soil temperature (Ts) showed a seasonal trend similar to Ctree. Analysis of this and other data from the literature confirmed that the sensitivity of tree conductance to soil temperature is related to the climatic origin of the plant species.The linear regression fitted to the relationship between Ctree and Ts was used to calculate soil temperature at apparent zero Ctree. This datum can be used as an index of plant sensitivity to root medium temperature. |
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Keywords: | leaf water potential soil temperature stomatal conductance weighing lysimeter |
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