title: The effect of water stress on super-high- density 'Koroneiki' olive oil quality.
abstract: BACKGROUND
  Over the last two decades, the area of cultivated super-high-density olive orchards has increased rapidly. Water stress is an important tool in super-high-density orchards to reduce tree growth and promote suitability for overhead mechanical harvesters. Little is known regarding the effect of water stress in super-high-density orchards on oil quality parameters. In this study the effect of irrigation rate on oil quality parameters was evaluated in a six-year-old super-high-density 'Koreneiki' olive orchard for five consecutive seasons. Five water status levels, determined by irrigating in order to maintain various midday stem water potential threshold values (-1.5, -2, -2.5, -3 and -4 MPa), were applied during the oil accumulation stage.
  
  
  RESULTS
  The MUFA/PUFA ratio and free fatty acid content generally decreased as a function of increasing tree water stress. In most seasons a reduction in polyphenols was found with decreasing irrigation level. Peroxide value was not affected by the water stress level.
  
  
  CONCLUSIONS
  The present study demonstrates that limiting irrigation and exposure of olive trees to water stress in a super-high-density orchard lowers free fatty acid content and therefore benefits oil quality. However, the decreased MUFA/PUFA ratio and the reduction in polyphenol content that were also found under increased water stress negatively influence oil quality.
authors.affiliation: Gilat Research Center, Agricultural Research Organization, M.P, Negev, 85280, Israel.
authors.forename: Arnon
authors.initials: A
authors.lastname: Dag
authors.affiliation: Golan Research Institute, PO Box 97, Kazrin, 12900, Israel.
authors.forename: Amos
authors.initials: A
authors.lastname: Naor
authors.affiliation: Gilat Research Center, Agricultural Research Organization, M.P, Negev, 85280, Israel.
authors.forename: Alon
authors.initials: A
authors.lastname: Ben-Gal
authors.affiliation: Gilat Research Center, Agricultural Research Organization, M.P, Negev, 85280, Israel.|Institute of Biochemistry, Food Science and Nutrition, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, PO Box 12, Rehovot, Israel.
authors.forename: Guy
authors.initials: G
authors.lastname: Harlev
authors.affiliation: Gilat Research Center, Agricultural Research Organization, M.P, Negev, 85280, Israel.
authors.forename: Isaac
authors.initials: I
authors.lastname: Zipori
authors.affiliation: MIGAL, Galilee Technology Center, PO Box 831, Kiryat Shemona, Israel.
authors.forename: Doron
authors.initials: D
authors.lastname: Schneider
authors.affiliation: Agriculture Valley Center, PO Box 73, Migdal HaEmeq, Israel.
authors.forename: Reuven
authors.initials: R
authors.lastname: Birger
authors.affiliation: The Extension Service, Ministry of Agriculture, Kiryat Shamona, 1210000, Israel.
authors.forename: Moti
authors.initials: M
authors.lastname: Peres
authors.affiliation: The Extension Service, Ministry of Agriculture, Kiryat Shamona, 1210000, Israel.
authors.forename: Yoni
authors.initials: Y
authors.lastname: Gal
authors.affiliation: Institute of Biochemistry, Food Science and Nutrition, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, PO Box 12, Rehovot, Israel.
authors.forename: Zohar
authors.initials: Z
authors.lastname: Kerem
mesh_terms: D057914:Agricultural Irrigation; D000383:Agriculture / Q000379:methods*; D003681:Dehydration; D005227:Fatty Acids / Q000737:chemistry; D031658:Olea / Q000502:physiology*; D000069463:Olive Oil / Q000737:chemistry* / Q000592:standards*; D059808:Polyphenols / Q000737:chemistry; D013997:Time Factors; D014867:Water
chemical_list: D005227:Fatty Acids; D000069463:Olive Oil; D059808:Polyphenols; D014867:Water
keywords: fatty acid profile; free fatty acid; irrigation; olive oil; super-high-density orchard