title: Direct in vivo evidence of immense stem water exploitation in irrigated date palms.
abstract: During the summer, evaporative demand at midday often exceeds the transport capacity of most desert plants. However, date palms maintain their ecological dominance with sustained and uniquely high rates of transpiration. This high rate of flow cannot be attributed to soil water supply alone. In order to quantify intra-plant water allocation in irrigated date palms, three water-sensing techniques have been incorporated: heat dissipation, gravimetric sampling, and time domain reflectrometry. Each of these methods has known limitations but their integration resulted in a quantitative in vivo accounting of the date palm diurnal and seasonal water mass balance. By incorporating these methods it was possible to determine that date palms substantially rely on the exploitation and recharge of the stem reservoir in their water budget. The stem of mature date palms can hold up to 1 m(3) of water and supply 25% of daily transpiration (i.e. 5000 l of water in 100 d of summer). The internal stem water reservoir is consistently recharged by over 50 l per night which allows for successive daytime reuse throughout the entire growing season. More broadly, these findings suggest that internal water allocation and night-time soil-water availability could provide useful information for improving date palm irrigation practices.
authors.affiliation: The Wyler Department of Dryland Agriculture, French Associates Institute for Agriculture and Biotechnology of Drylands, J. Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Israel Faculty of Agricultural, Food and Environmental Sciences, the Hebrew University of Jerusalem, Rehovot 76100, Israel orsperling@gmail.com.
authors.forename: Or
authors.initials: O
authors.lastname: Sperling
authors.affiliation: Faculty of Agricultural, Food and Environmental Sciences, the Hebrew University of Jerusalem, Rehovot 76100, Israel Northern R&D, Migal, Israel.
authors.forename: Or
authors.initials: O
authors.lastname: Shapira
authors.affiliation: Faculty of Agricultural, Food and Environmental Sciences, the Hebrew University of Jerusalem, Rehovot 76100, Israel.
authors.forename: Amnon
authors.initials: A
authors.lastname: Schwartz
authors.affiliation: The Wyler Department of Dryland Agriculture, French Associates Institute for Agriculture and Biotechnology of Drylands, J. Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Israel.
authors.forename: Naftali
authors.initials: N
authors.lastname: Lazarovitch
mesh_terms: D057914:Agricultural Irrigation; D001692:Biological Transport; D007557:Israel; D065749:Phoeniceae / Q000378:metabolism*; D018547:Plant Stems / Q000378:metabolism; D018526:Plant Transpiration; D014197:Trees / Q000378:metabolism; D014867:Water / Q000378:metabolism*
chemical_list: D014867:Water
keywords: Flow; in vivo; irrigation; stem; transpiration; water.