ISHS Acta Horticulturae 664: IV International Symposium on Irrigation of Horticultural Crops
IRRIGATION MANAGEMENT TO OPTIMIZE OLIVE GROWTH, PRODUCTION AND SENSORIAL OIL QUALITY |
| Authors: | M.J. Berenguer, S.R. Grattan, J.H. Connell, V.S. Polito, P.M. Vossen |
| Keywords: | Arbequina, high density, sensory evaluation, vegetative growth, yield |
| Abstract:
Irrigation management has a profound influence on both olive production and oil quality. In order to optimize oil production and quality, we initiated a study in the spring of 2002 to identify the optimal level of applied water on a high tree-density (spacing 1.5 m by 3.9 m) olive (Olea europaea L. ’Arbequina’) orchard. Irrigation water was applied differentially by drip irrigation to produce treatments of 15, 25, 40, 57, 71, 89, and 107% ET calculated from weather station ETo values and crop coefficients adjusted for changing canopy coverage. Tree growth was monitored by changes in trunk diameter and branch length. Final branch lengths of those from the two most water deprived treatments were half or less of those from the two highest irrigation treatments. Mid-day stem water potentials were measured periodically throughout the season and values ranged between –0.5 and –3.0 MPa and differences were consistent with the irrigation treatments. Stable isotope discrimination was an effective indicator of seasonal tree stress and was related to applied water. Fruits were harvested at two different times (31 Oct. and 18 Nov) to evaluate treatment effect in relation to harvest date. At each harvest, fruit production (kg/tree) was related (r2=0.84) to the natural log (ln) of the applied water. Delaying harvest slightly increased fruit production. Olive oil was extracted using the Abencor method and the percentage of oil in the fruit decreased linearly (r2=0.95) with increased applied water. The overall quantity of oil produced per tree, on the other hand, followed a second order function (r2=0.59 and 0.76) with a maximal quantity achieved between the 40 and 71% ET treatments. Wetter and dryer treatments produced less oil per tree. The date of harvest did not influence this zone of maximal oil production. Sensorial analyses indicated that fruitiness, bitterness, and pungency were all higher in trees receiving less irrigation but intermediate treatments produced oil with a nice balance of the three. | |
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