Effects of pre-harvest deficit irrigation during the oil accumulation period on fruit characteristics, oil yield extraction, and oil quality in olive cv. Genovesa in an arid region of Argentina

Abstract

The effect of pre-harvest deficit irrigation was studied as a tool to reduce fruit moisture and evaluate its influence on fruit characteristics, oil yield extraction, and oil quality. Two regulated deficit irrigation treatments (RDI) were evaluated over two seasons in a cv. Genovesa olive orchard. This study included a Control treatment, irrigated at 100% crop evapotranspiration over the season, and two RDI treatments, irrigated at 50% (RDI1) and 30% (RDI2) of Control. These treatments were applied from the end of pit hardening (mid-January) until harvest (early- April), when oil is accumulated in fruits. Fruit moisture decreased as the deficit irrigation period advanced, being significantly lower in RDI2 and RDI1 than in the Control treatment. Fruits harvested from the RDI2 treatment had lower moisture, dry mass and oil deposition, and higher maturation and pulp flavonoid compounds concentration than in RDI1 and Control. Pooled data across seasons showed that a 1% reduction in fruit moisture produced an increase of 0.16% in oil yield extraction. Phenolic compounds increased consistently with fruit moisture decreasing from 60% to 50%. However, when fruit moisture was as low as 35%, phenolic compounds were the lowest. Additional fruit samples from RDI2 were processed with water addition after malaxation. Water addition led to a general pattern of increases in oil yield extraction, reduction of phenolic compounds, and no influence on acidity, UV indexes, or fatty acids profile.