Effects of regulated deficit irrigation during stage III of fruit development on yield and oil quality of olive trees (Olea europaea L. 'Arbequina')
2011
Puertas, C.M. | Trentacoste, E.R. | Morabito, J.A. | Perez Pena, J.
In recent years, ‘Arbequina’ has been the most widely planted cultivar in Argentina. Its low polyphenol content and oxidative stability affect the oils’ commercial value. It has been suggested that reducing irrigation for olive trees may improve not only polyphenol content and oxidative stability, but also the percentage of oil extracted and water use efficiency. The effects of regulated deficit irrigation were evaluated in 9-year old ‘Arbequina’ olive orchard during growing seasons 2006-07 and 2007-08. Two levels of regulated deficit irrigation (RDI) and a control were imposed during stage III of fruit development until harvest: T66 and T33 received 66 and 33% respectively of the dose applied to the control treatment T (100% of crop evapotranspiration). Water status, leaf gas exchange, yield and oil quality parameters were evaluated. In both seasons T33 showed the lowest stem water potential generating a mild water stress. Stomatal conductance was similar among treatments. Yield and yield components (fruit weight, stone weight, humidity and oil content) were not affected by RDI treatments. During the second season, all treatments showed similar reductions in crop load compared to the first season, with no irrigation effects on alternate bearing pattern. Deficit irrigation did not affect oil yield. The quality parameters evaluated (free acidity, peroxide value, total polyphenol content and oxidative stability) were different between years. Total polyphenol content correlated with oxidative stability only in the second season (r=0.97). Irrigation treatment did not affect fatty acid composition. Water savings of 18 and 15% were achieved in T33 in the first and second growing season respectively.
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