ROUSSEAUX Maria Cecilia
congresos y reuniones científicas
Responses of oil yield and quality (cv. manzanilla) to regulated deficit irrigation from the late-summer to mid-autumn in northwest Argentina
San Juan
Simposio; VIIth International Symposium on Olive Growing; 2012
The elaboration of olive oil is the principal use of olive production in Northwest Argentina.  In most orchards, irrigation is reduced before harvest to better oil extractability (%) in the processing plants. Nevertheless, it is not well known how the induction of water stress affects oil characteristics in this region where autumn rainfall is uncommon. Thus, the objective of this study was to assess oil yield and quality under regulated deficit irrigation from late-summer to mid-autumn in cv. ‘Manzanilla’, a dual-purpose cultivar, over three consecutive growing seasons. The control and treatments were: 100% of crop evapotranspiration (100% ETc, control), 66% ETc (T66), 33% ETc, and no irrigation (T0).  The treatments were applied from approximately 25 February to 5 May in 2009-2011 in 10-year-old trees in a commercial orchard with a planting density of 312 trees per hectare in Aimogasta, La Rioja.  The stem water potential shortly before harvest ranged from -5.6 MPa for the T0 treatment to -2.3 MPa for the control. Oil yield per tree at harvest was often slightly less in the T0 treatment than the other RDI treatments and the control.  Oil yield per individual fruit was similar between the various treatments for much of the season, but was somewhat lower (15%) in both T0 and T33 than in T66 and the control at harvest. There were no differences in oil quality parameters between treatments for an early harvest, but acidity (%) and the peroxide index was greater in T0 when harvested late. Total phenols were greater in the T33 and T66 treatments relative to the control, but not in the T0. Reducing irrigation to 66% of full irrigation eight weeks before harvest maintained oil quantity and quality, and could be used successfully to lower fruit water content in commercial orchards in Northwest Argentina.