Dag, A., Gilat Research Center, Agricultural Research Organization, Negev, 85280, Israel
Naor, A., Golan Research Institute, PO Box 97, Kazrin, Israel
Ben-Gal, A., Gilat Research Center, Agricultural Research Organization, Negev, 85280, Israel
Harlev, G., Gilat Research Center, Agricultural Research Organization, 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
Zipori, I., Gilat Research Center, Agricultural Research Organization, Negev, 85280, Israel
Schneider, D., MIGAL, Galilee Technology Center, PO Box 831, Kiryat Shemona, Israel
Birger, R., Agriculture Valley Center, PO Box 73, Migdal HaEmeq, Israel
Peres, M., The Extension Service, Ministry of Agriculture, Kiryat Shamona, Israel
Gal, Y., The Extension Service, Ministry of Agriculture, Kiryat Shamona, Israel
Kerem, Z., 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
Dag, A., Gilat Research Center Agricultural Research Organization M.P Negev 85280 Israel
Naor, A., Golan Research Institute PO Box 97 Kazrin 12900 Israel
Ben-Gal, A., Gilat Research Center Agricultural Research Organization M.P Negev 85280 Israel
Harlev, G., 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
Zipori, I., Gilat Research Center Agricultural Research Organization M.P Negev 85280 Israel
Schneider, D., MIGAL, Galilee Technology Center PO Box 831 Kiryat Shemona Israel
Birger, R., Agriculture Valley Center PO Box 73 Migdal HaEmeq Israel
Peres, M., The Extension Service Ministry of Agriculture Kiryat Shamona 1210000 Israel
Gal, Y., The Extension Service Ministry of Agriculture Kiryat Shamona 1210000 Israel
Kerem, Z., 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

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. CONCLUSION: 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. © 2014 Society of Chemical Industry.