title: Fruit load governs transpiration of olive trees.
abstract: We tested the hypothesis that whole-tree water consumption of olives (Olea europaea L.) is fruit load-dependent and investigated the driving physiological mechanisms. Fruit load was manipulated in mature olives grown in weighing-drainage lysimeters. Fruit was thinned or entirely removed from trees at three separate stages of growth: early, mid and late in the season. Tree-scale transpiration, calculated from lysimeter water balance, was found to be a function of fruit load, canopy size and weather conditions. Fruit removal caused an immediate decline in water consumption, measured as whole-plant transpiration normalized to tree size, which persisted until the end of the season. The later the execution of fruit removal, the greater was the response. The amount of water transpired by a fruit-loaded tree was found to be roughly 30% greater than that of an equivalent low- or nonyielding tree. The tree-scale response to fruit was reflected in stem water potential but was not mirrored in leaf-scale physiological measurements of stomatal conductance or photosynthesis. Trees with low or no fruit load had higher vegetative growth rates. However, no significant difference was observed in the overall aboveground dry biomass among groups, when fruit was included. This case, where carbon sources and sinks were both not limiting, suggests that the role of fruit on water consumption involves signaling and alterations in hydraulic properties of vascular tissues and tree organs.
authors.affiliation: Gilat Research Center, Agricultural Research Organization, mobile post Negev 85280, Israel Desert Agro-Research Center, Ramat-Negev R&D, D.N. Halutza 85515, Israel.
authors.forename: Amnon
authors.initials: A
authors.lastname: Bustan
authors.affiliation: Gilat Research Center, Agricultural Research Organization, mobile post Negev 85280, Israel.
authors.forename: Arnon
authors.initials: A
authors.lastname: Dag
authors.affiliation: Gilat Research Center, Agricultural Research Organization, mobile post Negev 85280, Israel.
authors.forename: Uri
authors.initials: U
authors.lastname: Yermiyahu
authors.affiliation: Gilat Research Center, Agricultural Research Organization, mobile post Negev 85280, Israel.
authors.forename: Ran
authors.initials: R
authors.lastname: Erel
authors.affiliation: Gilat Research Center, Agricultural Research Organization, mobile post Negev 85280, Israel.
authors.forename: Eugene
authors.initials: E
authors.lastname: Presnov
authors.affiliation: Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Be'er Sheva 84990, Israel.
authors.forename: Nurit
authors.initials: N
authors.lastname: Agam
authors.affiliation: Gilat Research Center, Agricultural Research Organization, mobile post Negev 85280, Israel.
authors.forename: Dilia
authors.initials: D
authors.lastname: Kool
authors.affiliation: Gilat Research Center, Agricultural Research Organization, mobile post Negev 85280, Israel Soil Physics, Ecohydrology and Groundwater Management, Wageningen University, 6700AA Wageningen, The Netherlands Present address: Department of Civil Engineering, University of Bristol, Bristol BS8 1TR, UK.
authors.forename: Joost
authors.initials: J
authors.lastname: Iwema
authors.affiliation: Gilat Research Center, Agricultural Research Organization, mobile post Negev 85280, Israel.
authors.forename: Isaac
authors.initials: I
authors.lastname: Zipori
authors.affiliation: Gilat Research Center, Agricultural Research Organization, mobile post Negev 85280, Israel bengal@volcani.agri.gov.il.
authors.forename: Alon
authors.initials: A
authors.lastname: Ben-Gal
mesh_terms: D018533:Biomass; D005638:Fruit / Q000502:physiology*; D031658:Olea / Q000502:physiology*; D018515:Plant Leaves / Q000502:physiology; D018547:Plant Stems / Q000033:anatomy & histology / Q000502:physiology; D018526:Plant Transpiration / Q000502:physiology*; D012621:Seasons; D013997:Time Factors; D014197:Trees / Q000502:physiology*; D014867:Water
chemical_list: D014867:Water
keywords: Olea europaea; photosynthesis; stomatal regulation; vegetative growth; water potential; yield