Assessment of the effect of different deficit irrigation strategies on polyphenolic compounds of olives (cv. “Cobrançosa”)
Conference Paper
Overview
Research
Additional Document Info
View All
Overview
abstract
Olive tree (Olea europaea L.) is one of the most important fruit trees of Mediterranean countries due its food
products, table olives and olive oil that are well known by its high biophenol contents. Different water regimes
affect the general development and the composition of olive fruit [1] leading to slight changes in the taste of the
resulting oil [2] Particular attention has been given to the changes in phenolic compounds. Although this is not a
general effect and responses may differ in relation to the genotype, generally olives harvested from irrigated trees
show a lower accumulation of total phenols [3]. Contrasting evidence has not completely clarified the relation
between water availability and the oleuropein content in the drupes [4]. This study was undertaken to assess the
effect of different deficit irrigation strategies on polyphenolic compounds of olives.
Field trials took place in a typical olive growing area of Northeast Portugal region, Vilariça Valley (“Terra
Quente Transmontana”), in 2013 year in an irrigated olive orchard with “Cobrançosa Transmontana” cultivar.
Four irrigation regimes were applied: i) a well irrigated treatment (T1), that received a seasonal equivalent water
amount to satisfied crop evapotranspiration (100%ETc), irrigated on the two sides; three deficit irrigation
treatment: two sustained deficit irrigation treatment: ii) irrigated with 40% T1 on two side (SDI40) and iii)
irrigated with 75% T1 on two side 75% (SDI75) and a four treatment iv) Partial Root Drying System (PRD100),
irrigated with 100% of T1 on one side, switching every 15 days.
Total content of polyphenols (TP) and ortho-diphenols decreased during maturation and were affected by
irrigation treatment (p<0.05). At the first picking date, with maturation index (IM) = 0, no significant differences
were observed in TP between deficit irrigation treatments, with 19,072; 19,275 and 19,439 mg GAE kg-1 dw for
SDI40; SDI75 and PRD100, respectively. The differences were only observed between these and T1treatment
(100%ETc) that showed the lower values (15,270 mg GAE kg-1 dw). Curiously, at the harvest (IM = 3.2-3.5) the
highest values of TP were observed in SDI40 treatment with significant differences. TP in the others treatments
decreased and weren’t no different. Concerning to individual phenolic compounds, oleuropein and verbascoside
are the most representative in all treatments. Olives with higher values (149.96 ½g. g-1 dw) of oleuropein were
submitted to the higher level of water deficit (SDI40), followed by treatments SDI75 (143.55 ½g.g-1 dw), PRD100
(125.78 ½g.g-1 dw) and finally by 100% ETc (122.53 ½g.g-1 dw). Verbascoside was the main hydroxycinnamic
acid present in olives, with the higher values observed in treatments with low irrigation (SDI40 and PRD100). The
content of the individual phenolic compounds including phenolic alcohols, and secoiridoids were affected by
irrigation, being lower with the increase of the amount of water applied.
